Internet DRAFT - draft-faibish-nfsv4-pnfs-lustre-layout
draft-faibish-nfsv4-pnfs-lustre-layout
NFSv4 Working Group S. Faibish
Internet-Draft D. Cote
Intended status: draft P. Tao
Expires: November 5, 2014 EMC Corporation
May 5, 2014
Parallel NFS (pNFS) Lustre Layout Operations
draft-faibish-nfsv4-pnfs-lustre-layout-07
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Abstract
Parallel NFS (pNFS) extends Network File System version 4.1(NFSv4.1)
to allow clients to directly access file data on the storage used by
the NFSv4.1 server. This ability to bypass the server for data
access can increase both performance and parallelism, but requires
additional client functionality for data access, some of which is
dependent on the class of storage used, a.k.a. the Layout Type. The
main pNFS operations and data types in NFSv4 Minor version 1 specify
a layout-type-independent layer; layout-type-specific information is
conveyed using opaque data structures whose internal structure is
further defined by the particular layout type specification. This
document specifies the NFSv4.1 Lustre pNFS Layout Type as a
companion to the main NFSv4 Minor version 1 specification.
Table of Contents
1. Introduction...................................................3
1.1. pNFS Lustre Layout Protocol...............................3
1.2. General Definitions.......................................5
1.3. Lustre Protocol Description...............................6
2. Conventions Used in this Document..............................7
3. XDR Description of the Lustre-Based Layout Protocol............7
3.1. Code Components Licensing Notice..........................7
4. Basic Data Type Definitions....................................9
4.1. pnfs_los_object_cred4....................................10
4.2. Data Stripping Algorithms................................11
5. Object Storage Server Addressing and Discovery................11
5.1. pnfs_los_targetid_type4..................................12
5.2. pnfs_los_deviceaddr4.....................................12
5.2.1. OSS Target Identifier...............................12
5.2.2. Device Network Address..............................12
6. Lustre-Based Layout...........................................13
6.1. pnfs_lov_mds_md..........................................13
6.2. pnfs_los_layout4.........................................15
6.3. Data Mapping Schemes.....................................15
6.3.1. Simple Striping.....................................16
6.4. RAID Algorithms..........................................17
6.4.1. PNFS_OST_RAID_0.....................................18
6.4.2. PNFS_OST_RAID_1.....................................18
7. Lustre-Based Creation Layout Hint.............................18
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7.1. pnfs_los_layouthint4.....................................18
8. IANA Considerations...........................................20
9. References....................................................20
9.1. Normative References.....................................20
Authors' Addresses...............................................22
1. Introduction
1.1. pNFS Lustre Layout Protocol
Figure 1 shows the overall architecture of a Parallel NFS (pNFS)
Protocol ([8]) system:
+-----------+
|+-----------+ +-----------+
||+-----------+ | |
||| | NFSv4.1 + pNFS | |
+|| Clients |<------------------------------>| MDS |
+| | | |
+-----------+ | |
||| +-----------+
||| |
||| |
||| Storage +-----------+ |
||| Protocol |+-----------+ |
||+----------------||+-----------+ Control |
|+-----------------||| | Protocol |
+------------------+|| Storage |------------+
+| Devices |
+-----------+
Figure 1 pNFS Architecture
In this document, "storage device" is used as a general term for a
data server and/or storage server for all pNFS layouts. The
MetaData Server (MDS) is the NFSv4.1 server that provides pNFS
layouts to clients and handles operations on file metadata (e.g.,
names, attributes).
In pNFS, the file server returns typed layout structures that
describe where file data is located. There are different layouts for
different storage systems and methods of arranging data on storage
devices. This document describes the layouts used with Lustre object
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storage servers (OSSs) that are accessed according to the Lustre
storage protocol ([1]).
The pNFS Lustre layout protocol uses Lustre file system protocols as
data storage protocol. Implementation-wise, on both pNFS client and
server, the pNFS Lustre layout can live as a shim layer on top of
Lustre client and server, as shown in Figure 2.
+-----------+
| +----------+ +-----------+
| | Generic | NFSv4.1 + pNFS | Generic |
| | pNFS |<---------------------------->| pNFS |
| | Client | | Server |
| +----------+ +-----------+
| | pNFS | | pNFS |
| | Lustre | | Lustre |
| | Layout | | Layout |
| | Client | | Server |
| | Driver | | Driver |
| +----------+ +-----------+
| | Lustre | | Lustre |
+ | Client | | MDS |
+----------+ +-----------+
| | | |
| | | |
| | | |
| | | |
| | | |
| | Lustre +-------------+ Lustre | |
| | Protocol | +------------+ Protocol | |
| +------------| | |------------+ |
+--------------| | Lustre OSS |--------------+
+ | |
+------------+
Figure 2 pNFS Lustre client/server Architecture
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1.2. General Definitions
The following definitions provide an appropriate context for the
reader.
+-----------------+------------------------------------------------+
| Lustre module | Description |
+-----------------+------------------------------------------------+
| OST | Object Storage Targets are SCSI LUNs which |
| | store file data objects |
| | |
| OSS | An Object Storage Sever implements the Lustre |
| | data protocol and serves data |
| | |
| OSC | An Object Storage Client [10] is a client of |
| | the Lustre object services |
| | |
| LOV | LOV is the Lustre Object Volume [10]. It |
| | interprets stripe information and directs pages|
| | to the correct OSCs. |
| | |
| MDT | A Metadata Target is a SCSI LUN that stores |
| | file metadata |
| | |
| MDS | A Metadata Sever implements the Lustre |
| | metadata server control protocol |
| | |
| MDC | A Metadata Client of Lustre protocol services |
| | |
| LDLM | The Lustre Distributed Lock Manager (LDLM) [11]|
| | provides a means to ensure that data is updated|
| | in a consistent fashion across multiple nodes. |
| | |
| PTLRPC | The Portal RPC subsystem [12] is a reliable |
| | messaging service layered on top of LNET. It |
| | caters for small messages and also for bulk |
| | data transfers. |
| | |
| LNET | LNET is the Lustre Networking sub-system [13]. |
| | It hides differences of underlying network |
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| | types and provides common APIs to LNET users. |
| | |
| LND | LND is the Lustre Network Driver layer [13]. It|
| | implements the interface between the generic |
| | LNET layer and the drivers for the specific |
| | network types. |
+-----------------+------------------------------------------------+
1.3. Lustre Protocol Description
Lustre is an object-based file system. It is composed of three
components: Metadata servers (MDSs), object storage servers (OSSs),
and Lustre clients.
Lustre uses block devices (SCSI LUNs) for file data storage (OST)
and metadata storages (MDT) and each block device can be managed by
only one Lustre server (OSS). The total data capacity of the Lustre
filesystem is the sum of all individual OST capacities. Lustre
clients access and concurrently use data through the standard POSIX
I/O system calls.
A Lustre MDS provides metadata services. One Lustre MDS manages one
metadata target (MDT). Each MDT stores file metadata, such as file
names, directory structures, and access permissions. An OSS exposes
block devices and serves data. Each OSS manages one or more object
storage targets (OSTs), and OSTs store file data "objects".
The Lustre protocol specifies several operations on objects,
including OPEN, READ, WRITE, GET ATTRIBUTES, SET ATTRIBUTES, CREATE,
and DELETE. However, using the Lustre layout the Lustre client only
uses the OPEN, READ, WRITE and GET ATTRIBUTES commands. The other
commands are only used by the Lustre server.
A Lustre file object's layout information is defined in the extended
attribute (EA) of the inode. Essentially, EA describes the mapping
between file object identifier and its corresponding OSTs. This
information is also known as striping. A Lustre-based layout for
pNFS includes object identifiers, capabilities that allow pNFS
clients to READ or WRITE those objects, and various parameters that
control how file data is striped across OSTs.
This document specifies the NFSv4.1 layout protocol and operations
for Lustre filesystems ([1]).
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2. Conventions Used in this Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [6].
3. XDR Description of the Lustre-Based Layout Protocol
This document contains the external data representation (XDR [2])
description of the NFSv4.1 objects layout protocol. The XDR
description is embedded in this document in a way that makes it
simple for the reader to extract into a ready-to-compile form. The
reader can feed this document into the following shell script to
produce the machine readable XDR description of the NFSv4.1 Lustre
layout protocol:
#!/bin/sh
grep '^ *///' $* | sed 's?^ */// ??' | sed 's?^ *///$??'
That is, if the above script is stored in a file called
"extract.sh", and this document is in a file called "spec.txt", then
the reader can do:
sh extract.sh < spec.txt > pnfs_lustre_prot.x
The effect of the script is to remove leading white space from each
line, plus a sentinel sequence of "///".
The embedded XDR file header follows. Subsequent XDR descriptions,
with the sentinel sequence are embedded throughout the document.
Note that the XDR code contained in this document depends on types
from the NFSv4.1 nfs4_prot.x file ([3]). This includes both nfs
types that end with a 4, such as offset4, length4, etc., as well as
more generic types such as uint32_t and uint64_t.
3.1. Code Components Licensing Notice
The XDR description, marked with lines beginning with the sequence
"///", as well as scripts for extracting the XDR description are
Code Components as described in Section 4 of "Legal Provisions
Relating to IETF Documents" [4]. These Code Components are licensed
according to the terms of Section 4 of "Legal Provisions Relating to
IETF Documents".
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/// /*
/// * Copyright (c) 2014 IETF Trust and the persons identified
/// * as authors of the code. All rights reserved.
/// *
/// * Redistribution and use in source and binary forms, with
/// * or without modification, are permitted provided that the
/// * following conditions are met:
/// *
/// * o Redistributions of source code must retain the above
/// * copyright notice, this list of conditions and the
/// * following disclaimer.
/// *
/// * o Redistributions in binary form must reproduce the above
/// * copyright notice, this list of conditions and the
/// * following disclaimer in the documentation and/or other
/// * materials provided with the distribution.
/// *
/// * o Neither the name of Internet Society, IETF or IETF
/// * Trust, nor the names of specific contributors, may be
/// * used to endorse or promote products derived from this
/// * software without specific prior written permission.
/// *
/// * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
/// * AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
/// * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
/// * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
/// * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
/// * EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
/// * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
/// * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
/// * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
/// * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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/// * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/// *
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///
/// /*
/// * pnfs_lustre_prot.x
/// */
///
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/// %#include <nfs4_prot.x>
///
4. Basic Data Type Definitions
The following sections define basic data types and constants used by
the Lustre Layout protocol.
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4.1. pnfs_los_object_cred4
/// enum pnfs_los_cap_key_sec4 {
/// PNFS_OSS_CAP_KEY_SEC_NONE = 0,
/// PNFS_OSS_CAP_KEY_SEC_SSV = 1
/// };
///
/// typedef uint64_t pnfs_los_objid4;
///
/// struct pnfs_los_object_cred4 {
/// pnfs_los_objid4 ploc_object_id;
/// pnfs_los_cap_key_sec4 ploc_cap_key_sec;
/// opaque ploc_capability_key<>;
/// opaque ploc_capability<>;
/// };
///
Lustre PTLRPC supports GSS authentication. PTLRPC implements Lustre
communications over LNET ([1]). So "pnfs_los_object_cred4" is put
inside pnfs_los_layout4 so that if the network requires security,
credentials can be passed around.
The pnfs_los_object_cred4 structure is used to identify each
component comprising the file. The "ploc_object_id" identifies the
component object, the "ploc_capability_key" provide the OSS security
credentials needed to access that object. The "ploc_cap_key_sec"
value denotes the method used to secure the "ploc_capability_key".
To comply with the Lustre security requirements, the capability key
SHOULD be transferred securely to prevent eavesdropping. Therefore,
a client SHOULD either issue the LAYOUTGET or GETDEVICEINFO
operations via RPCSEC_GSS with the privacy service or previously
establish a secret state verifier (SSV) for the sessions via the
NFSv4.1 SET_SSV operation. The pnfs_los_cap_key_sec4 type is used to
identify the method used by the server to secure the capability key.
o PNFS_OSS_CAP_KEY_SEC_NONE denotes that the "ploc_capability_key"
is not encrypted, in which case the client SHOULD issue the
LAYOUTGET or GETDEVICEINFO operations with RPCSEC_GSS with the
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privacy service or the NFSv4.1 transport should be secured by
using methods that are external to NFSv4.1 like the use of IPsec
([5]) for transporting the NFSV4.1 protocol.
o PNFS_OSS_CAP_KEY_SEC_SSV denotes that the "ploc_capability_key"
contents are encrypted using the SSV GSS context and the
capability key as inputs to the GSS_Wrap() function (see GSS-API
[7]) with the conf_req_flag set to TRUE. The client MUST use the
secret SSV key as part of the client's GSS context to decrypt the
capability key using the value of the lc_capability_key field as
the input_message to the GSS_unwrap() function. Note that to
prevent eavesdropping of the SSV key, the client SHOULD issue
SET_SSV via RPCSEC_GSS with the privacy service.
The actual method chosen depends on whether the client established a
SSV key with the server and whether it issued the operation with the
RPCSEC_GSS privacy method. Naturally, if the client did not
establish an SSV key via SET_SSV, the server MUST use the
PNFS_OSS_CAP_KEY_SEC_NONE method. Otherwise, if the operation was
not issued with the RPCSEC_GSS privacy method, the server SHOULD
secure the "ploc_capability_key" with the PNFS_OSS_CAP_KEY_SEC_SSV
method. The server MAY use the PNFS_OSS_CAP_KEY_SEC_SSV method also
when the operation was issued with the RPCSEC_GSS privacy method.
4.2. Data Stripping Algorithms
Currently only RAID0 is supported but Lustre defines RAID1 as well.
/// const LOV_PATTERN_RAID0 = 0x001
/// /* stripes are used round-robin */
/// const LOV_PATTERN_RAID1 = 0x002
/// /* stripes are mirrors of each other */
5. Object Storage Server Addressing and Discovery
Data operations to an OSS require the client to know the "address"
of each OSS's root object. The OSS exposes block devices and serves
data. Correspondingly, OSC is client of the services. Each OSS
manages one or more OSTs, and OSTs store file data objects. Because
these representations are local, GETDEVICEINFO must return
information that can be used by the client to select the correct
local representation.
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5.1. pnfs_los_targetid_type4
The following enum specifies the manner in which an OST can be
specified. The target can be specified by the network access
protocol type used.
/// enum pnfs_los_targetid_type4 {
/// LOS_TARGET_TCP = 1,
/// LOS_TARGET_IB = 2
/// };
Where:
o LOS_TARGET_TCP denotes use of the TCP protocol
o LOS_TARGET_IB denotes use of the IB protocol
Only TCP and IB are defined because these are the two most widely
used networks in High Performance Computing deployments.
5.2. pnfs_los_deviceaddr4
The specification (according to [9]) for an object device address is
as follows:
/// struct pnfs_los_deviceaddr4 {
/// netaddr4 lda_targetid;
/// opaque lda_ossname<>;
/// };
5.2.1. OSS Target Identifier
When "lda_targetid" is specified the opaque field MUST be formatted
as the LOS name.
5.2.2. Device Network Address
The network address is given with the netaddr4 type, which specifies
a TCP/IP or IB based endpoint (as specified in NFSv4.1 [3]). When
given, the client SHOULD use it to probe for the OSS device at the
given network address. The client MAY still use other discovery
mechanisms to locate the device using the "lda_targetid". In
particular, an external name service (external to data protocol
coming from LNET) SHOULD be used when the devices may be attached to
the network using multiple connections, and/or multiple storage
fabrics (e.g., TCP or IB).
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6. Lustre-Based Layout
The layout4 type is defined in the NFSv4.1 ([3]) as follows:
enum layouttype4 {
LAYOUT4_NFSV4_1_FILES= 0x1,
LAYOUT4_OSD2_OBJECTS = 0x2,
LAYOUT4_BLOCK_VOLUME = 0x3,
LAYOUT4_OSS_OBJECTS = 0x0BD30BD4 /* Tentatively */
};
struct layout_content4 {
layouttype4 loc_type;
opaque loc_body<>;
};
struct layout4 {
offset4 lo_offset;
length4 lo_length;
layoutiomode4 lo_iomode;
layout_content4 lo_content;
};
This document defines structure associated with the layouttype4
value, LAYOUT4_OSS_OBJECTS. The NFSv4.1 ([3]) specifies the
loc_body structure as an XDR type "opaque". The opaque layout is
uninterpreted by the generic pNFS client layers, but obviously must
be interpreted by the Lustre storage layout driver. This section
defines the structure of this opaque value, "pnfs_oss_layout4".
6.1. pnfs_lov_mds_md
There are two kinds of MDS metadata in the Lustre protocol. For pNFS
we decided to only support V3 that is in use since Lustre 2.0
release. The other V1 metadata is not considered to be supported in
this draft.
These are the key file mapping data structures. "pnfs_lov_ost_data"
is per-stripe data structure. "lov_mds_md" is per file data
structure.
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/// struct pnfs_lov_ost_data4 { /* per-stripe data structure */
/// uint64_t l_object_id; /* OST object ID */
/// uint64_t l_object_seq; /* OST object seq number */
/// uint32_t l_ost_gen;
/// /* generation of this l_ost_idx */
/// uint32_t l_ost_idx;
/// /* OST index in LOV (lov_tgt_desc->tgts) */
/// };
///
/// #define LOV_MAXPOOLNAME 16
///
/// struct pnfs_lov_mds_md { /* LOV EA mds/wire data */
/// uint32_t lmm_pattern;
/// /* LOV_PATTERN_RAID0, LOV_PATTERN_RAID1 */
/// uint64_t lmm_object_id; /* LOV object ID */
/// uint64_t lmm_object_seq; /* LOV object seq number */
/// uint32_t lmm_stripe_size; /* size of stripe in bytes */
/// uint16_t lmm_stripe_count;
/// /* num stripes in use for this object */
/// uint16_t lmm_layout_gen; /* layout generation number */
/// char lmm_pool_name[LOV_MAXPOOLNAME];
/// /* must be 32bit aligned */
/// pnfs_lov_ost_data4 lmm_objects[0]; /*per-stripe data*/
/// };
///
The pnfs_"pnfs_lov_ost_data4" structure parameterizes the algorithm
that maps a file's contents over the component OST's.
The "pnfs_lov_ost_data4" is a per stripe data structure that defines
the location of the stripe in OST and which OST holds the data.
"l_object_id" holds the file data's object ID on the OST.
"l_object_seq" holds the object sequence number which is always 0.
"l_ost_idx" holds the OST's index in LOV, and "l_ost_gen" holds the
OST's index generation.
The "lmm_pattern" holds the file's stripping pattern. It can be
either LOV_PATTERN_RAID0 or LOV_PATTERN_RAID1. "lmm_object_id" holds
the MDS object ID. "lmm_object_seq" holds the LOV object sequence
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number.
"lmm_stripe_size" holds the stripe size in bytes. A file is striped
across multiple OSTs in the same stripe size. The "lmm_stripe_count"
holds the number of OSTs over which the file is striped.
"llm_layout_gen" holds the generation of current layout information.
Clients need to obtain layout generation before IO and check layout
generation after IO. If layout generation is changed, client needs
to redo the operations.
The "lmm_objects" is an array of "lmm_stripe_count" members
containing per OST file information. Each element is in form of
struct "pnfs_lov_ost_data".
6.2. pnfs_los_layout4
The following is the opaque data in generic layout.
/// struct pnfs_los_layout4 {
/// pnfs_lov_mds_md lov_mds_md;
/// pnfs_los_object_cred4 llo_component;
/// };
///
The "llo_component" is of type "pnfs_los_object_cred4", containing
credentials that Lustre client needs to use to connect to OSS's.
Note that the layout depends on the file size, which the client
learns, by doing GETATTR commands to the pNFS metadata server.
The pNFS client uses the file size to decide if it should return a
short read of the file when trying to read beyond the file size.
6.3. Data Mapping Schemes
This section describes the different data mapping schemes in detail.
The Lustre layout always uses a "dense" layout as described in
NFSv4.1 ([3]). This means that the second stripe unit of the file
starts at offset 0 of the second component, rather than at offset
stripe_unit bytes. After a full stripe has been written, the next
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stripe unit is appended to the first component object in the list
without any holes in the component objects. From the MDS point of
view, each file is composed of multiple data objects striped on one
or more OSTs.
6.3.1. Simple Striping
A file object's layout information is defined in the extended
attribute (EA) of the inode. Essentially, EA describes the mapping
between file object id and its corresponding OSTs.
For example, if file A has a stripe count of three, then its EA will
look like:
EA ---> <obj id x, ost p>
<obj id y, ost q>
<obj id z, ost r>
stripe size and stripe width
In the above equation obj_id is the object identifier of a file
fragment on the ost p, "stripe size" is the size of each file
segment on one OST and "stripe width" is the number of OST's used.
So if the "stripe size" is 1MB, and the "stripe width" is 3, then
this would mean that: [0,1M), [4M,5M), ... are stored as object x,
which is on OST p; [1M, 2M), [5M, 6M), ... are stored as object y,
which is on OST q; [2M,3M), [6M, 7M), ... are stored as object z,
which is on OST r.
Before reading the file, the pNFS client will query the pNFS MDS and
be informed that it should talk to <ost p, ost q, ost r> for this
operation. This information is structured in so-called LSM, and
Lustre client side LOV (logical object volume) is to interpret this
information so Lustre client can send requests to OSTs. Here again,
the Lustre client communicates with OST through a client module
interface known as OSC. Depending on the context, OSC can also be
used to refer to an OSS client by itself.
The mapping from the logical offset within a file (L) to the
component object C and object-specific offset O is defined by the
following equations:
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L = logical offset into the file
W = stripe width
S = stripe size
C = (L-L%S)%W
O = L/W/S+L%S
In these equations, S is the number of bytes in a full stripe or
stripe size. C is an index into the array of components, so it
selects a particular OST device. C count starts from zero. O is the
offset within the OST that corresponds to the file offset. Note that
this computation does accommodate the fact that an object includes
all the file segments that are located on same OST.
For example, consider an object striped over three devices,
<OST0 OST1 OST2>. The stripe size is 1024KB. The stripe width W is
thus 3.
Offset 0KB:
C = (0-0%1)%3 = 0 (OST0)
O = 0/3/1024 + (0%1024) = 0
Offset 1024KB:
C = (1024-(1024%1024))%3 = 1 (OST1)
O = 1024/3/1024 +(1024%1024) = 0
Offset 9000KB:
C = (9000-(9000%1024))%3 = 2 (OST2)
O = 9000/3/1024 + (9000%1024) = 810
Offset 102400KB:
C = (102400-(102400%1024))%3 = 1 (OST0)
O = 102400/3/1024 + (102400%4096) = 33
6.4. RAID Algorithms
This section defines the different redundancy algorithms. Note: The
term "RAID" (Redundant Array of Independent Disks) is used in this
document to represent an array of component OST's that store data
for an individual file. The objects are stored on independent OST-
based storage devices. File data is encoded and striped across the
array of component OST's using algorithms developed for block-based
RAID systems.
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6.4.1. PNFS_OST_RAID_0
PNFS_OST_RAID_0 means there is no parity data, so all bytes in the
component objects are data bytes located by the above equations for
C and O.
6.4.2. PNFS_OST_RAID_1
PNFS_OST_RAID_1 means there is no parity data, but each OST is
mirrored to another OST. In this case the component objects are data
bytes still located by the above equations for C and O, defined in
section 6.3.1.
7. Lustre-Based Creation Layout Hint
The layouthint4 type is defined in the NFSv4.1 ([3]) as follows:
struct layouthint4 {
layouttype4 loh_type;
opaque loh_body<>;
};
The "layouthint4" structure is used by the client to pass a hint
about the type of layout it would like to be created for a
particular file. If the "loh_type" layout type is
LAYOUT4_OSS_OBJECTS, then the "loh_body" opaque value is defined by
the "pnfs_oss_layouthint4" type.
7.1. pnfs_los_layouthint4
/// union pnfs_lov_stripe_count_hint4 switch (bool lsc_valid) {
/// case TRUE:
/// uint32_t lsc_stripe_count;
/// case FALSE:
/// void;
/// };
///
/// union pnfs_lov_stripe_size_hint4 switch (bool lss_valid) {
/// case TRUE:
/// uint32_t lss_stripe_size;
/// case FALSE:
/// void;
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/// };
///
/// union pnfs_lov_stripe_offset_hint4 switch (bool lso_valid) {
/// case TRUE:
/// uint32_t lso_stripe_offset;
/// case FALSE:
/// void;
/// };
///
/// union pnfs_lov_stripe_pattern_hint4 switch (bool lsp_valid) {
/// case TRUE:
/// uint32_t lsp_stripe_pattern;
/// case FALSE:
/// void;
/// };
///
/// union pnfs_lov_pool_hint4 switch (bool lp_valid) {
/// case TRUE:
/// string lp_pool_name<>;
/// case FALSE:
/// void;
/// };
///
/// enum pnfs_lov_data_tier {
/// LOV_DATA_PRIMARY = 1;
/// LOV_DATA_SECONDARY = 2;
/// };
///
/// union pnfs_lov_data_tiering_hint4 switch (bool lp_valid) {
/// case TRUE:
/// ldt_data_tier;
/// case FALSE:
/// void;
/// };
///
/// struct pnfs_los_layouthint4 {
/// pnfs_lov_stripe_count_hint4 lov_stripe_count_hint;
/// pnfs_lov_stripe_size_hint4 lov_stripe_size_hint;
/// pnfs_lov_stripe_offset_hint4 lov_stripe_offset_hint;
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/// pnfs_lov_stripe_pattern_hint4 lov_stripe_pattern_hint;
/// pnfs_lov_pool_hint4 lov_pool_hint;
/// pnfs_lov_data_tiering_hint4 lov_data_tiering_hint;
/// };
///
"pnfs_los_layouthint4" conveys hints for the desired data map. Hints
are indications of the client for preferences of the data stripe
type to be used for the file. All parameters are optional so the
client can give values for only the parameters it cares about.
"lov_stripe_count_hint", "lov_stripe_size_hint",
"lov_stripe_offset_hint" and "lov_stripe_pattern_hint" tells server
that client wants to create a file with corresponding stripe count,
stripe size, stripe offset and stripe pattern. "lov_pool_hint" tells
server that client wants to create a file within specific OST pool.
"lov_data_tiering_hint" tells server with tiering support, that if
client wants to store data in primary (usually fast) storage tier.
The server should make an attempt to honor the hints, but it can
ignore any or all of them at its own discretion and without failing
the respective CREATE operation.
8. IANA Considerations
As described in NFSv4.1 ([8]), new layout type numbers have been
assigned by IANA. This document defines the protocol associated
with a new layout type number, LAYOUT4_OSS_OBJECTS, and it requires
to be assigned a new value from IANA.
9. References
9.1. Normative References
[1] http://www.scribd.com/doc/59271212/Understanding-Lustre-
File-System-Internals. Lustre source code is hosted in
http://git.whamcloud.com/?p=fs/lustre-
release.git;a=summary. The Lustre client code is also in
process of being merged in Linux kernel.
https://git.kernel.org/cgit/linux/kernel/
git/torvalds/linux.git/tree/drivers/staging
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[2] Eisler, M., "XDR: External Data Representation Standard",
STD 67, RFC 4506, May 2006.
[3] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
External Data Representation Standard (XDR) Description",
RFC 5662, January 2010.
[4] IETF Trust, "Legal Provisions Relating to IETF Documents",
November 2008, http://trustee.ietf.org/docs/IETF-Trust-
License-Policy.pdf.
[5] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[6] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[7] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000.
[8] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
Protocol", RFC 5661, January 2010.
[9] Eisler, M., "IANA Considerations for Remote Procedure Call
(RPC) Network Identifiers and Universal Address Formats",
RFC 5665, January 2010.
[10] LOV and OSC.
http://wiki.lustre.org/lid/ulfi/ulfi_lov_osc.html
[11] Lustre Distributed Lock Manager.
http://wiki.lustre.org/lid/agi/agi_ldlm.html
[12] Portal RPC. http://wiki.lustre.org/lid/agi/agi_ptlrpc.html
[13] Lustre Networking.
http://wiki.lustre.org/lid/agi/agi_lnet.html
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Sorin Faibish (editor)
EMC Corporation
228 South Street
Hopkinton, MA 01748
US
Phone: +1 (508) 249-5745
Email: sfaibish@emc.com
Dominique Cote
EMC Corporation
228 South Street
Hopkinton, MA 01748
US
Phone: +1 (508) 249-5781
Email: dominique.cote@emc.com
Peng Tao
EMC Corporation
8F, Block D, SP Tower
Tsinghua Science Park
Zhongguancun Dong Road
Beijing 100084
PRC
Phone: +86 (10) 8215 8293
Email: bergwolf@gmail.com
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