draft-ietf-nfsv4-pnfs-block-01.txt   draft-ietf-nfsv4-pnfs-block-02.txt 
NFSv4 Working Group David L. Black NFSv4 Working Group David L. Black
Internet Draft Stephen Fridella Internet Draft Stephen Fridella
Expires: February 28, 2007 EMC Corporation Expires: August 2007 Jason Glasgow
August 30, 2006 Intended Status: Proposed Standard EMC Corporation
February 21, 2007
pNFS Block/Volume Layout pNFS Block/Volume Layout
draft-ietf-nfsv4-pnfs-block-01.txt draft-ietf-nfsv4-pnfs-block-02.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that By submitting this Internet-Draft, each author represents that
any applicable patent or other IPR claims of which he or she is any applicable patent or other IPR claims of which he or she is
aware have been or will be disclosed, and any of which he or she aware have been or will be disclosed, and any of which he or she
becomes aware will be disclosed, in accordance with Section 6 of becomes aware will be disclosed, in accordance with Section 6 of
BCP 79. BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
skipping to change at page 1, line 34 skipping to change at page 1, line 35
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
This Internet-Draft will expire in February 2007. This Internet-Draft will expire in August 2007.
Abstract Abstract
Parallel NFS (pNFS) extends NFSv4 to allow clients to directly access Parallel NFS (pNFS) extends NFSv4 to allow clients to directly access
file data on the storage used by the NFSv4 server. This ability to file data on the storage used by the NFSv4 server. This ability to
bypass the server for data access can increase both performance and bypass the server for data access can increase both performance and
parallelism, but requires additional client functionality for data parallelism, but requires additional client functionality for data
access, some of which is dependent on the class of storage used. The access, some of which is dependent on the class of storage used. The
main pNFS operations draft specifies storage-class-independent main pNFS operations draft specifies storage-class-independent
extensions to NFS; this draft specifies the additional extensions extensions to NFS; this draft specifies the additional extensions
skipping to change at page 2, line 24 skipping to change at page 2, line 26
2. Block Layout Description.......................................3 2. Block Layout Description.......................................3
2.1. Background and Architecture...............................3 2.1. Background and Architecture...............................3
2.2. Data Structures: Extents and Extent Lists.................4 2.2. Data Structures: Extents and Extent Lists.................4
2.2.1. Layout Requests and Extent Lists.....................6 2.2.1. Layout Requests and Extent Lists.....................6
2.2.2. Layout Commits.......................................7 2.2.2. Layout Commits.......................................7
2.2.3. Layout Returns.......................................8 2.2.3. Layout Returns.......................................8
2.2.4. Client Copy-on-Write Processing......................9 2.2.4. Client Copy-on-Write Processing......................9
2.2.5. Extents are Permissions.............................10 2.2.5. Extents are Permissions.............................10
2.2.6. End-of-file Processing..............................11 2.2.6. End-of-file Processing..............................11
2.3. Volume Identification....................................12 2.3. Volume Identification....................................12
2.4. Crash Recovery Issues....................................14 2.4. Crash Recovery Issues....................................15
3. Security Considerations.......................................14 3. Security Considerations.......................................15
4. Conclusions...................................................16 4. Conclusions...................................................16
5. IANA Considerations...........................................16 5. IANA Considerations...........................................17
6. Revision History..............................................16 6. Revision History..............................................17
7. Acknowledgments...............................................17 7. Acknowledgments...............................................18
8. References....................................................17 8. References....................................................18
8.1. Normative References.....................................17 8.1. Normative References.....................................18
8.2. Informative References...................................18 8.2. Informative References...................................18
Author's Addresses...............................................18 Author's Addresses...............................................19
Intellectual Property Statement..................................18 Intellectual Property Statement..................................19
Disclaimer of Validity...........................................19 Disclaimer of Validity...........................................20
Copyright Statement..............................................19 Copyright Statement..............................................20
Acknowledgment...................................................19 Acknowledgment...................................................20
1. Introduction 1. Introduction
Figure 1 shows the overall architecture of a pNFS system: Figure 1 shows the overall architecture of a pNFS system:
+-----------+ +-----------+
|+-----------+ +-----------+ |+-----------+ +-----------+
||+-----------+ | | ||+-----------+ | |
||| | NFSv4 + pNFS | | ||| | NFSv4 + pNFS | |
+|| Clients |<------------------------------>| Server | +|| Clients |<------------------------------>| Server |
skipping to change at page 4, line 36 skipping to change at page 4, line 36
read-only and uninitialized storage for the same range in a layout. read-only and uninitialized storage for the same range in a layout.
Reads are initially performed on the read-only storage, with writes Reads are initially performed on the read-only storage, with writes
going to the uninitialized storage. After the first write that going to the uninitialized storage. After the first write that
initializes the uninitialized storage, all reads are performed to initializes the uninitialized storage, all reads are performed to
that now-initialized writeable storage, and the corresponding read- that now-initialized writeable storage, and the corresponding read-
only storage is no longer used. only storage is no longer used.
2.2. Data Structures: Extents and Extent Lists 2.2. Data Structures: Extents and Extent Lists
A pNFS block layout is a list of extents within a flat array of 512- A pNFS block layout is a list of extents within a flat array of 512-
byte data blocks known as a volume. A volume may correspond to a byte data blocks in a storage volume. The details of the volume
single logical unit in a SAN, or a more complex aggregation of topology can be determined by using the GETDEVICEINFO or
multiple logical units. The details of the volume topology can be GETDEVICELIST operation (see discussion of volume identification,
determined by using the GETDEVICEINFO or GETDEVICELIST operation (see section 2.3 below). The block layout describes the individual block
discussion of volume identification, section 2.3 below). The block extents on the volume that make up the file.
layout describes the individual block extents on the volume that make
up the file. Each individual extent MUST be at least 512-byte
aligned.
enum extentState4 { enum pnfs_block_extent_state4 {
READ_WRITE_DATA = 0, /* the data located by this extent is valid READ_WRITE_DATA = 0, /* the data located by this extent is valid
for reading and writing. */ for reading and writing. */
READ_DATA = 1, /* the data located by this extent is valid READ_DATA = 1, /* the data located by this extent is valid
for reading only; it may not be written. for reading only; it may not be written.
*/ */
INVALID_DATA = 2, /* the location is valid; the data is INVALID_DATA = 2, /* the location is valid; the data is
invalid. It is a newly (pre-) allocated invalid. It is a newly (pre-) allocated
extent. There is physical space on the extent. There is physical space on the
volume. */ volume. */
NONE_DATA = 3, /* the location is invalid. It is a hole in NONE_DATA = 3, /* the location is invalid. It is a hole in
the file. There is no physical space on the file. There is no physical space on
the volume. */ the volume. */
}; };
struct pnfs_block_extent { struct pnfs_block_extent4 {
offset4 offset; /* the starting offset in the offset4 offset; /* the starting offset in the
file */ file */
length4 length; /* the size of the extent */ length4 length; /* the size of the extent */
offset4 storage_offset; /* the starting offset in the offset4 storage_offset; /* the starting offset in the
volume */ volume */
extentState4 es; /* the state of this extent */ pnfs_block_extent_state4 es; /* the state of this extent */
}; };
struct pnfs_block_layout { struct pnfs_block_layout4 {
pnfs_deviceid4 volume; /* logical volume on which file deviceid4 volume; /* logical volume on which file
is stored. */ is stored. */
pnfs_block_extent extents<>; /* extents which make up this pnfs_block_extent4 extents<>; /* extents which make up this
layout. */ layout. */
}; };
The block layout consists of an identifier of the logical volume on The block layout consists of an identifier of the logical volume on
which the file is stored, followed by a list of extents which map the which the file is stored, followed by a list of extents which map the
logical regions of the file to physical locations on the volume. The logical regions of the file to physical locations on the volume. The
"storage_offset" field within each extent identifies a location on "storage_offset" field within each extent identifies a location on
the logical volume described by the "volume" field in the layout. the logical volume described by the "volume" field in the layout.
The client is responsible for translating this logical offset into an The client is responsible for translating this logical offset into an
offset on the appropriate underlying SAN logical unit. offset on the appropriate underlying SAN logical unit.
Each extent maps a logical region of the file onto a portion of the Each extent maps a logical region of the file onto a portion of the
specified logical volume. The file_offset, extent_length, and es specified logical volume. The file_offset, extent_length, and es
fields for an extent returned from the server are always valid. The fields for an extent returned from the server are always valid. The
interpretation of the storage_offset field depends on the value of es interpretation of the storage_offset field depends on the value of es
as follows: as follows (in increasing order):
o READ_WRITE_DATA means that storage_offset is valid, and points to o READ_WRITE_DATA means that storage_offset is valid, and points to
valid/initialized data that can be read and written. valid/initialized data that can be read and written.
o READ_DATA means that storage_offset is valid and points to valid/ o READ_DATA means that storage_offset is valid and points to valid/
initialized data which can only be read. Write operations are initialized data which can only be read. Write operations are
prohibited; the client may need to request a read-write layout. prohibited; the client may need to request a read-write layout.
o INVALID_DATA means that storage_offset is valid, but points to o INVALID_DATA means that storage_offset is valid, but points to
invalid uninitialized data. This data must not be physically read invalid uninitialized data. This data must not be physically read
from the disk until it has been initialized. A read request for from the disk until it has been initialized. A read request for
an INVALID_DATA extent must fill the user buffer with zeros. Write an INVALID_DATA extent must fill the user buffer with zeros. Write
requests must write whole server-sized blocks to the disk with requests must write whole server-sized blocks to the disk; bytes
bytes not initialized by the user must be set to zero. Any write not initialized by the user must be set to zero. Any write to
to storage in an INVALID_DATA extent changes the written portion storage in an INVALID_DATA extent changes the written portion of
of the extent to READ_WRITE_DATA; the pNFS client is responsible the extent to READ_WRITE_DATA; the pNFS client is responsible for
for reporting this change via LAYOUTCOMMIT. reporting this change via LAYOUTCOMMIT.
o NONE_DATA means that storage_offset is not valid, and this extent o NONE_DATA means that storage_offset is not valid, and this extent
may not be used to satisfy write requests. Read requests may be may not be used to satisfy write requests. Read requests may be
satisfied by zero-filling as for INVALID_DATA. NONE_DATA extents satisfied by zero-filling as for INVALID_DATA. NONE_DATA extents
are returned by requests for readable extents; they are never may be returned by requests for readable extents; they are never
returned if the request was for a writeable extent. returned if the request was for a writeable extent.
The extent list lists all relevant extents in increasing order of the An extent list lists all relevant extents in increasing order of the
file_offset of each extent; any ties are broken by increasing order file_offset of each extent; any ties are broken by increasing order
of the extent state (es). of the extent state (es).
2.2.1. Layout Requests and Extent Lists 2.2.1. Layout Requests and Extent Lists
Each request for a layout specifies at least three parameters: Each request for a layout specifies at least three parameters:
offset, desired size, and minimum size. If the status of a request offset, desired size, and minimum size. If the status of a request
indicates success, the extent list returned must meet the following indicates success, the extent list returned must meet the following
criteria: criteria:
skipping to change at page 7, line 34 skipping to change at page 7, line 34
contiguous. Every READ_DATA extent in a read-write layout MUST be contiguous. Every READ_DATA extent in a read-write layout MUST be
covered by an INVALID_DATA extent. This overlap of READ_DATA and covered by an INVALID_DATA extent. This overlap of READ_DATA and
INVALID_DATA extents is the only permitted extent overlap. INVALID_DATA extents is the only permitted extent overlap.
o Extents MUST be ordered in the list by starting offset, with o Extents MUST be ordered in the list by starting offset, with
READ_DATA extents preceding INVALID_DATA extents in the case of READ_DATA extents preceding INVALID_DATA extents in the case of
equal file_offsets. equal file_offsets.
2.2.2. Layout Commits 2.2.2. Layout Commits
struct pnfs_block_layoutupdate { struct pnfs_block_layoutupdate4 {
pnfs_block_extent commit_list<>; /* list of extents to which now pnfs_block_extent4 commit_list<>;/* list of extents to which now
contain valid data. */ contain valid data. */
bool make_version; /* client requests server to bool make_version; /* client requests server to
create copy-on-write image of create copy-on-write image of
this file. */ this file. */
} }
The "pnfs_block_layoutupdate" structure is used by the client as the The "pnfs_block_layoutupdate4" structure is used by the client as the
block-protocol specific argument in a LAYOUTCOMMIT operation. The block-protocol specific argument in a LAYOUTCOMMIT operation. The
"commit_list" field is an extent list covering regions of the file "commit_list" field is an extent list covering regions of the file
layout that were previously in the INVALID_DATA state, but have been layout that were previously in the INVALID_DATA state, but have been
written by the client and should now be considered in the written by the client and should now be considered in the
READ_WRITE_DATA state. It should be noted that the server may be READ_WRITE_DATA state. The es field of each extent in the
unable to commit regions at a granularity smaller than a file-system commit_list MUST be set to READ_WRITE_DATA. Implementers should be
block (typically 4KB or 8KB). As noted above, the block-size that aware that a server may be unable to commit regions at a granularity
the server uses is available as an NFSv4 attribute, and any extents smaller than a file-system block (typically 4KB or 8KB). As noted
included in the "commit_list" must be aligned on this granularity. above, the block-size that the server uses is available as an NFSv4
If the client believes that its actions have moved the end-of-file attribute, and any extents included in the "commit_list" MUST be
into the middle of a block being committed, the client MUST write aligned to this granularity and have a size that is a multiple of
zeroes from the end-of-file to the end of that block before this granularity. If the client believes that its actions have moved
committing the block. Failure to do so may result in junk the end-of-file into the middle of a block being committed, the
(uninitialized data) appearing in that area if the file is client MUST write zeroes from the end-of-file to the end of that
block before committing the block. Failure to do so may result in
junk (uninitialized data) appearing in that area if the file is
subsequently extended by moving the end-of-file. subsequently extended by moving the end-of-file.
The "make_version" field of the structure is a flag that the client The "make_version" field of the structure is a flag that the client
may set to request that the server create a copy-on-write image of may set to request that the server create a copy-on-write image of
the file (pNFS clients may be involved in this operation - see the file (pNFS clients may be involved in this operation - see
section 2.2.4, below). In anticipation of this operation the client section 2.2.4, below). In anticipation of this operation the client
which sets the "make_version" flag in the LAYOUTCOMMIT operation which sets the "make_version" flag in the LAYOUTCOMMIT operation
should immediately mark all extents in the layout that is possesses should immediately mark all extents in the layout that is possesses
as state READ_DATA. Future writes to the file require a new as state READ_DATA. Future writes to the file require a new
LAYOUTGET operation to the server with an "iomode" set to LAYOUTGET operation to the server with an "iomode" set to
LAYOUTIOMODE_RW. LAYOUTIOMODE_RW.
2.2.3. Layout Returns 2.2.3. Layout Returns
struct pnfs_block_layoutreturn { struct pnfs_block_layoutreturn4 {
pnfs_block_extent rel_list<>; /* list of extents the client pnfs_block_extent4 rel_list<>; /* list of extents the client
will no longer use. */ will no longer use. */
} }
The "rel_list" field is an extent list covering regions of the file The "rel_list" field is an extent list covering regions of the file
layout that are no longer needed by the client. Including extents in layout that are no longer needed by the client. Including extents in
the "rel_list" for a LAYOUTRETURN operation represents an explicit the "rel_list" for a LAYOUTRETURN operation represents an explicit
release of resources by the client, usually done for the purpose of release of resources by the client, usually done for the purpose of
avoiding unnecessary CB_LAYOUTRECALL operations in the future. avoiding unnecessary CB_LAYOUTRECALL operations in the future.
skipping to change at page 9, line 4 skipping to change at page 9, line 5
revocation. When a layout is unilaterally revoked by the server, revocation. When a layout is unilaterally revoked by the server,
usually due to the client's lease timer expiring or the client usually due to the client's lease timer expiring or the client
failing to return a layout in a timely manner, it is important for failing to return a layout in a timely manner, it is important for
the sake of correctness that any in-flight I/Os that the client the sake of correctness that any in-flight I/Os that the client
issued before the layout was revoked are rejected at the storage. issued before the layout was revoked are rejected at the storage.
For the block/volume protocol, this is possible by fencing a client For the block/volume protocol, this is possible by fencing a client
with an expired layout timer from the physical storage. Note, with an expired layout timer from the physical storage. Note,
however, that the granularity of this operation can only be at the however, that the granularity of this operation can only be at the
host/logical-unit level. Thus, if one of a client's layouts is host/logical-unit level. Thus, if one of a client's layouts is
unilaterally revoked by the server, it will effectively render unilaterally revoked by the server, it will effectively render
useless *all* of the client's layouts for files in the same useless *all* of the client's layouts for files located on the
filesystem. storage units comprising the logical volume. This may render useless
the client's layouts for files in other filesystems.
2.2.4. Client Copy-on-Write Processing 2.2.4. Client Copy-on-Write Processing
Distinguishing the READ_WRITE_DATA and READ_DATA extent types in Distinguishing the READ_WRITE_DATA and READ_DATA extent types in
combination with the allowed overlap of READ_DATA extents with combination with the allowed overlap of READ_DATA extents with
INVALID_DATA extents allows copy-on-write processing to be done by INVALID_DATA extents allows copy-on-write processing to be done by
pNFS clients. In classic NFS, this operation would be done by the pNFS clients. In classic NFS, this operation would be done by the
server. Since pNFS enables clients to do direct block access, it is server. Since pNFS enables clients to do direct block access, it is
useful for clients to participate in copy-on-write operations. All useful for clients to participate in copy-on-write operations. All
block/volume pNFS clients MUST support this copy-on-write processing. block/volume pNFS clients MUST support this copy-on-write processing.
skipping to change at page 10, line 25 skipping to change at page 10, line 27
pNFS server in control of potentially conflicting storage device pNFS server in control of potentially conflicting storage device
operations, enabling the server to determine what does conflict and operations, enabling the server to determine what does conflict and
how to avoid conflicts by granting and recalling extents to/from how to avoid conflicts by granting and recalling extents to/from
clients. clients.
Block/volume class storage devices are not required to perform read Block/volume class storage devices are not required to perform read
and write operations atomically. Overlapping concurrent read and and write operations atomically. Overlapping concurrent read and
write operations to the same data may cause the read to return a write operations to the same data may cause the read to return a
mixture of before-write and after-write data. Overlapping write mixture of before-write and after-write data. Overlapping write
operations can be worse, as the result could be a mixture of data operations can be worse, as the result could be a mixture of data
from the two write operations; this can be particularly nasty if the from the two write operations; data corruption can occur if the
underlying storage is striped and the operations complete in underlying storage is striped and the operations complete in
different orders on different stripes. A pNFS server can avoid these different orders on different stripes. A pNFS server can avoid these
conflicts by implementing a single writer XOR multiple readers conflicts by implementing a single writer XOR multiple readers
concurrency control policy when there are multiple clients who wish concurrency control policy when there are multiple clients who wish
to access the same data. This policy SHOULD be implemented when to access the same data. This policy SHOULD be implemented when
storage devices do not provide atomicity for concurrent read/write storage devices do not provide atomicity for concurrent read/write
and write/write operations to the same data. and write/write operations to the same data.
A client that makes a layout request that conflicts with an existing If a client makes a layout request that conflicts with an existing
layout delegation will be rejected with the error layout delegation, the request will be rejected with the error
NFS4ERR_LAYOUTTRYLATER. This client is then expected to retry the NFS4ERR_LAYOUTTRYLATER. This client is then expected to retry the
request after a short interval. During this interval the server request after a short interval. During this interval the server
needs to recall the conflicting portion of the layout delegation from SHOULD recall the conflicting portion of the layout delegation from
the client that currently holds it. This reject-and-retry approach the client that currently holds it. This reject-and-retry approach
does not prevent client starvation when there is contention for the does not prevent client starvation when there is contention for the
layout of a particular file. For this reason a pNFS server SHOULD layout of a particular file. For this reason a pNFS server SHOULD
implement a mechanism to prevent starvation. One possibility is that implement a mechanism to prevent starvation. One possibility is that
the server can maintain a queue of rejected layout requests. Each the server can maintain a queue of rejected layout requests. Each
new layout request can be checked to see if it conflicts with a new layout request can be checked to see if it conflicts with a
previous rejected request, and if so, the newer request can be previous rejected request, and if so, the newer request can be
rejected. Once the original requesting client retries its request, rejected. Once the original requesting client retries its request,
its entry in the rejected request queue can be cleared, or the entry its entry in the rejected request queue can be cleared, or the entry
in the rejected request queue can be removed when it reaches a in the rejected request queue can be removed when it reaches a
skipping to change at page 11, line 18 skipping to change at page 11, line 20
ultimately arrive at the NFSv4 server for processing, the server is ultimately arrive at the NFSv4 server for processing, the server is
in a position to enforce these restrictions. However, with pNFS in a position to enforce these restrictions. However, with pNFS
layout delegations, I/Os will be issued from the clients that hold layout delegations, I/Os will be issued from the clients that hold
the delegations directly to the storage devices that host the data. the delegations directly to the storage devices that host the data.
These devices have no knowledge of files, mandatory locks, or share These devices have no knowledge of files, mandatory locks, or share
reservations, and are not in a position to enforce such restrictions. reservations, and are not in a position to enforce such restrictions.
For this reason the NFSv4 server MUST NOT grant layout delegations For this reason the NFSv4 server MUST NOT grant layout delegations
that conflict with mandatory locks or share reservations. Further, that conflict with mandatory locks or share reservations. Further,
if a conflicting mandatory lock request or a conflicting open request if a conflicting mandatory lock request or a conflicting open request
arrives at the server, the server MUST recall the part of the layout arrives at the server, the server MUST recall the part of the layout
delegation in conflict with the request before processing the delegation in conflict with the request before granting the request.
request.
2.2.6. End-of-file Processing 2.2.6. End-of-file Processing
The end-of-file location can be changed in two ways: implicitly as The end-of-file location can be changed in two ways: implicitly as
the result of a WRITE or LAYOUTCOMMIT beyond the current end-of-file, the result of a WRITE or LAYOUTCOMMIT beyond the current end-of-file,
or explicitly as the result of a SETATTR request. Typically, when a or explicitly as the result of a SETATTR request. Typically, when a
file is truncated by an NFSv4 client via the SETATTR call, the server file is truncated by an NFSv4 client via the SETATTR call, the server
frees any disk blocks belonging to the file which are beyond the new frees any disk blocks belonging to the file which are beyond the new
end-of-file byte, and may write zeros to the portion of the new end- end-of-file byte, and may write zeros to the portion of the new end-
of-file block beyond the new end-of-file byte. These actions render of-file block beyond the new end-of-file byte. These actions render
skipping to change at page 12, line 27 skipping to change at page 12, line 27
possible, hence network address are difficult to use for volume possible, hence network address are difficult to use for volume
identification. For this reason, this pNFS block layout identifies identification. For this reason, this pNFS block layout identifies
storage volumes by content, for example providing the means to match storage volumes by content, for example providing the means to match
(unique portions of) labels used by volume managers. Any block pNFS (unique portions of) labels used by volume managers. Any block pNFS
system using this layout MUST support a means of content-based unique system using this layout MUST support a means of content-based unique
volume identification that can be employed via the data structure volume identification that can be employed via the data structure
given here. given here.
struct sigComponent { /* disk signature component */ struct sigComponent { /* disk signature component */
offset4 sig_offset; /* byte offset of component */ int64_t sig_offset; /* byte offset of component
from start of volume if positive
from end of volume if negative */
length4 sig_length; /* byte length of component */ length4 sig_length; /* byte length of component */
opaque contents<>; /* contents of this component of the opaque contents<>; /* contents of this component of the
signature (this is opaque) */ signature (this is opaque) */
}; };
enum pnfs_block_volume_type { enum pnfs_block_volume_type4 {
VOLUME_SIMPLE = 0, /* volume maps to a single LU */ VOLUME_SIMPLE = 0, /* volume maps to a single LU */
VOLUME_SLICE = 1, /* volume is a slice of another volume */ VOLUME_SLICE = 1, /* volume is a slice of another volume */
VOLUME_CONCAT = 2, /* volume is a concatenation of multiple VOLUME_CONCAT = 2, /* volume is a concatenation of multiple
volumes */ volumes */
VOLUME_STRIPE = 3, /* volume is striped across multiple VOLUME_STRIPE = 3, /* volume is striped across multiple
volumes */ volumes */
skipping to change at page 12, line 47 skipping to change at page 13, line 4
VOLUME_SIMPLE = 0, /* volume maps to a single LU */ VOLUME_SIMPLE = 0, /* volume maps to a single LU */
VOLUME_SLICE = 1, /* volume is a slice of another volume */ VOLUME_SLICE = 1, /* volume is a slice of another volume */
VOLUME_CONCAT = 2, /* volume is a concatenation of multiple VOLUME_CONCAT = 2, /* volume is a concatenation of multiple
volumes */ volumes */
VOLUME_STRIPE = 3, /* volume is striped across multiple VOLUME_STRIPE = 3, /* volume is striped across multiple
volumes */ volumes */
}; };
struct pnfs_block_slice_volume_info {
struct pnfs_block_slice_volume_info4 {
offset4 start; /* block-offset of the start of the offset4 start; /* block-offset of the start of the
slice */ slice */
length4 length; /* length of slice in blocks */ length4 length; /* length of slice in blocks */
pnfs_deviceid4 volume; /* volume which is sliced */ deviceid4 volume; /* volume which is sliced */
}; };
struct pnfs_block_concat_volume_info { struct pnfs_block_concat_volume_info4 {
pnfs_deviceid4 volumes<>; /* volumes which are concatenated */ deviceid4 volumes<>; /* volumes which are concatenated */
}; };
struct pnfs_block_stripe_volume_info { struct pnfs_block_stripe_volume_info4 {
length4 stripe_unit; /* size of stripe */ length4 stripe_unit; /* size of stripe */
pnfs_deviceid4 volumes<>; /* volumes which are striped deviceid4 volumes<>; /* volumes which are striped
across*/ across*/
}; };
union pnfs_block_deviceaddr4 switch (pnfs_block_volume_type type) { union pnfs_block_deviceaddr4 switch (pnfs_block_volume_type4 type) {
case VOLUME_SIMPLE: case VOLUME_SIMPLE:
sigComponent ds<MAX_SIG_COMP>; /* disk signature */ pnfs_block_sig_component4 ds<MAX_SIG_COMP>; /*
disk signature */
case VOLUME_SLICE: case VOLUME_SLICE:
pnfs_block_slice_volume_info slice_info; pnfs_block_slice_volume_info4 slice_info;
case VOLUME_CONCAT: case VOLUME_CONCAT:
pnfs_block_concat_volume_info concat_info; pnfs_block_concat_volume_info4 concat_info;
case VOLUME_STRIPE: case VOLUME_STRIPE:
pnfs_block_stripe_volume_info stripe_info; pnfs_block_stripe_volume_info4 stripe_info;
default: default:
void; void;
}; };
The "pnfs_block_deviceaddr4" union is a recursive structure that The "pnfs_block_deviceaddr4" union is a recursive structure that
allows arbitrarily complex nested volume structures to be encoded. allows arbitrarily complex nested volume structures to be encoded.
The types of aggregations that are allowed are stripes, The types of aggregations that are allowed are stripes,
skipping to change at page 14, line 28 skipping to change at page 14, line 32
"sigComponent" structure. Each SAN logical unit is content- "sigComponent" structure. Each SAN logical unit is content-
identified by a disk signature made up of extents within blocks and identified by a disk signature made up of extents within blocks and
contents that must match. The "pnfs_block_deviceaddr4" union is contents that must match. The "pnfs_block_deviceaddr4" union is
returned by the server as the storage-protocol-specific opaque field returned by the server as the storage-protocol-specific opaque field
in the "pnfs_deviceaddr4" structure, in response to the GETDEVICEINFO in the "pnfs_deviceaddr4" structure, in response to the GETDEVICEINFO
or GETDEVICELIST operations. Note that the opaque "contents" field or GETDEVICELIST operations. Note that the opaque "contents" field
in the "sigComponent" structure MUST NOT be interpreted as a zero- in the "sigComponent" structure MUST NOT be interpreted as a zero-
terminated string, as it may contain embedded zero-valued octets. It terminated string, as it may contain embedded zero-valued octets. It
contains exactly sig_length octets. There are no restrictions on contains exactly sig_length octets. There are no restrictions on
alignment (e.g., neither sig_offset nor sig_length are required to be alignment (e.g., neither sig_offset nor sig_length are required to be
multiples of 4). multiples of 4). The sig_offset is a signed quantity which when
positive represents an offset from the start of the volume, and when
negative represents an offset from the end of the volume.
Negative offsets are permitted in order to simplify the client
implementation on systems where the device label is found at a fixed
offset from the end of the volume. In the absence of a negative
offset, imagine a system where the client has access to n volumes and
a file system is striped across m volumes. If those m disks are all
different sizes, then in the worst case, the client would need to
read n times m blocks in order to properly identify the volumes used
by a layout. If the server uses negative offsets to describe the
signature, then the client and server MUST NOT see different volume
sizes. Negative offsets SHOULD NOT be used in systems that
dynamically resize volumes unless care is taken to ensure that the
device label is always present at the offset from the end of the
volume as seen by the clients.
2.4. Crash Recovery Issues 2.4. Crash Recovery Issues
When the server crashes while the client holds a writable layout, and When the server crashes while the client holds a writable layout, and
the client has written data to blocks covered by the layout, and the the client has written data to blocks covered by the layout, and the
blocks are still in the INVALID_DATA state, the client has two blocks are still in the INVALID_DATA state, the client has two
options for recovery. If the data that has been written to these options for recovery. If the data that has been written to these
blocks is still cached by the client, the client can simply re-write blocks is still cached by the client, the client can simply re-write
the data via NFSv4, once the server has come back online. However, the data via NFSv4, once the server has come back online. However,
if the data is no longer in the client's cache, the client MUST NOT if the data is no longer in the client's cache, the client MUST NOT
skipping to change at page 17, line 27 skipping to change at page 18, line 5
structures contain extent lists instead of a single extent. Updated structures contain extent lists instead of a single extent. Updated
section 2.1.6 to remove references to CB_SIZECHANGED. Moved section 2.1.6 to remove references to CB_SIZECHANGED. Moved
description of recovery from "Issues" section to "Block Layout description of recovery from "Issues" section to "Block Layout
Description" section. Removed section 3.2 "End-of-file handling Description" section. Removed section 3.2 "End-of-file handling
issues". Merged old "block/volume layout security considerations" issues". Merged old "block/volume layout security considerations"
section from previous version of [NFSv4.1] with section 4. Moved section from previous version of [NFSv4.1] with section 4. Moved
paragraph on lingering writes to the section which describes layout paragraph on lingering writes to the section which describes layout
return. Removed Issues section (3) as the remaining issues are all return. Removed Issues section (3) as the remaining issues are all
resolved. resolved.
02: Changed pnfs_deviceaddr4 to deviceaddr4 to match [NFSv4.1].
Updated section 2.2.2 to clarify that the es fields must be
READ_WRITE_DATA in pnfs_block_layoutupdate requests. Updated section
2.2.5 to specify that data corruption can occur; that requests, not
the client, are rejected; that server "SHOULD" recall conflicting
portions of layouts. Clarified that unilateral revocation may affect
layouts from other filesystems. Changed signature offset to be a
signed quantity to allow for labels at a fixed location from the end
of a volume. Changed all data structures to have suffix "4", changed
extentState4 to pnfs_block_extent_state4 and sigComponent to
pnfs_block_sig_component4, to conform to [NFSv4.1].
7. Acknowledgments 7. Acknowledgments
This draft draws extensively on the authors' familiarity with the This draft draws extensively on the authors' familiarity with the
mapping functionality and protocol in EMC's HighRoad system mapping functionality and protocol in EMC's HighRoad system
[HighRoad]. The protocol used by HighRoad is called FMP (File [HighRoad]. The protocol used by HighRoad is called FMP (File
Mapping Protocol); it is an add-on protocol that runs in parallel Mapping Protocol); it is an add-on protocol that runs in parallel
with filesystem protocols such as NFSv3 to provide pNFS-like with filesystem protocols such as NFSv3 to provide pNFS-like
functionality for block/volume storage. While drawing on HighRoad functionality for block/volume storage. While drawing on HighRoad
FMP, the data structures and functional considerations in this draft FMP, the data structures and functional considerations in this draft
differ in significant ways, based on lessons learned and the differ in significant ways, based on lessons learned and the
skipping to change at page 17, line 50 skipping to change at page 18, line 40
(formerly with IBM). (formerly with IBM).
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[NFSV4.1] Shepler, S., Eisler, M., and Noveck, D. ed., "NFSv4 Minor [NFSV4.1] Shepler, S., Eisler, M., and Noveck, D. ed., "NFSv4 Minor
Version 1", draft-ietf-nfsv4-minorversion1-06.txt, Internet Version 1", draft-ietf-nfsv4-minorversion1-08.txt, Internet
Draft, August 2006. Draft, October 2006.
8.2. Informative References 8.2. Informative References
[HighRoad] EMC Corporation, "EMC Celerra HighRoad", EMC C819.1 white [HighRoad] EMC Corporation, "EMC Celerra HighRoad", EMC C819.1 white
paper, available at: paper, available at:
http://www.emc.com/pdf/products/celerra_file_server/HighRoad_wp.pdf http://www.emc.com/pdf/products/celerra_file_server/HighRoad_wp.pdf
link checked 29 August 2006. link checked 29 August 2006.
Author's Addresses Author's Addresses
David L. Black David L. Black
EMC Corporation EMC Corporation
176 South Street 176 South Street
Hopkinton, MA 01748 Hopkinton, MA 01748
Phone: +1 (508) 293-7953 Phone: +1 (508) 293-7953
Email: black_david@emc.com Email: black_david@emc.com
Stephen Fridella Stephen Fridella
EMC Corporation EMC Corporation
228 South Street
Hopkinton, MA 01748
Phone: +1 (508) 249-3528
Email: fridella_stephen@emc.com
Jason Glasgow
EMC Corporation
32 Coslin Drive 32 Coslin Drive
Southboro, MA 01772 Southboro, MA 01772
Phone: +1 (508) 305-8512 Phone: +1 (508) 305 8831
Email: fridella_stephen@emc.com Email: glasgow_jason@emc.com
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
skipping to change at page 19, line 12 skipping to change at page 20, line 15
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf- this standard. Please address the information to the IETF at ietf-
ipr@ietf.org. ipr@ietf.org.
Disclaimer of Validity Disclaimer of Validity
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
 End of changes. 49 change blocks. 
85 lines changed or deleted 124 lines changed or added

This html diff was produced by rfcdiff 1.33. The latest version is available from http://tools.ietf.org/tools/rfcdiff/