source: gpfs_3.1_ker2.6.20/share/man/man8/mmcrfs.8 @ 118

.TH mmcrfs 12/04/06
mmcrfs Command
.SH "Name"
.PP
\fBmmcrfs\fR - Creates a GPFS file system.
.SH "Synopsis"
.PP
\fBmmcrfs\fR \fIMountpoint \fR \fIDevice\fR
{"\fIDiskDesc\fR[;\fIDiskDesc\fR...]"
| \fB-F\fR \fIDescFile\fR} [\fB-A\fR {\fB\fIyes\fR\fR | \fBno
| automount\fR}] [\fB-D {\fR\fBnfs4\fR | \fB\fIposix\fR\fR\fB}\fR] [\fB-B\fR \fIBlockSize\fR]
[\fB-E\fR {\fB\fIyes\fR\fR | \fBno\fR}] [\fB-j
{\fR\fBcluster | scatter}\fR] [\fB-k {\fR\fB\fIposix\fR\fR\fB | nfs4 | all}\fR] [\fB-K {\fR\fBno\fR |
\fB\fIwhenpossible\fR\fR | \fBalways}\fR] [\fB-m\fR
\fIDefaultMetadataReplicas\fR] [\fB-M \fR
\fIMaxMetadataReplicas\fR] [\fB-n\fR \fINumNodes\fR]
[\fB-N\fR
\fINumInodes\fR[:\fINumInodesToPreallocate\fR]]
[\fB-Q\fR {\fByes\fR | \fB\fIno\fR\fR}] [\fB-r \fR
\fIDefaultDataReplicas\fR] [\fB-R\fR
\fIMaxDataReplicas\fR] [\fB-S\fR {\fByes\fR | \fB\fIno\fR\fR}] [\fB-v\fR {\fB\fIyes\fR\fR | \fBno\fR}]
[\fB-z\fR {\fByes\fR | \fB\fIno\fR\fR}]
.SH "Description"
.PP
Use the \fBmmcrfs\fR command to create a GPFS file system. The first
three options \fImust\fR be \fIMountpoint\fR, \fIDevice\fR, and
either \fIDiskDescList\fR or \fIDescFile\fR and they \fImust\fR be
in that order. The block size and replication factors chosen affect
file system performance. There is a maximum of 32 file systems that may
be mounted in a GPFS cluster at one time, including remote file
systems.
.PP
When deciding on the maximum number of
files (number of inodes) in a file system, consider that for file systems that
will be doing parallel file creates, if the total number of free inodes is not
greater than 5% of the total number of inodes, there is the potential for
slowdown in file system access. The total number of inodes can be
increased using the \fBmmchfs\fR command.
.PP
When deciding on a block size for a file system, consider these points:
.RS +3
.HP 3
1. Supported block sizes are 16 KB, 64 KB 256 KB, 512 KB, 1 MB, 2 MB, 4
MB.
.HP 3
2. The GPFS block size determines:
.RS +3
.HP 3
\(bu The minimum disk space allocation unit. The minimum amount of space
that file data can occupy is a subblock. A subblock is 1/32 of the
block size.
.HP 3
\(bu The maximum size of a read or write request that GPFS sends to the
underlying disk driver.
.RE
.HP 3
3. 
From a performance perspective, you are advised to set the GPFS block size to
match either the application buffer size, the RAID stripe size, or a multiple
of the RAID stripe size. If the GPFS block size does not match the RAID
stripe size, performance may be severely degraded, especially for write
operations.
.HP 3
4. In file systems with a high degree of variance in the size of files within
the file system, using a small block size would have a large impact on
performance when accessing large files. In this kind of system it is
suggested that you use a block size of 256 KB (8 KB subblock). Even if
only 1% of the files are large, the amount of space taken by the large files
usually dominates the amount of space used on disk, and the waste in the
subblock used for small files is usually insignificant. For further
performance information, see the GPFS white papers at
www.ibm.com/servers/eserver/clusters/library/wp_aix_lit.html.
.HP 3
5. The effect of block size on file system performance largely depends on the
application I/O pattern. 
.RS +3
.HP 3
\(bu A larger block size is often beneficial for large sequential read and
write workloads.
.HP 3
\(bu A smaller block size is likely to offer better performance for small file,
small random read and write, and metadata-intensive workloads.
.RE
.HP 3
6. The efficiency of many algorithms that rely on caching file data in a GPFS
page pool depends more on the number of blocks cached rather than the absolute
amount of data. For a page pool of a given size, a larger file system
block size would mean fewer blocks cached. Therefore, when you create
file systems with a block size larger than the default 256 KB, it is
recommended that you increase the page pool size in proportion to the block
size.
.HP 3
7. The file system block size may not exceed the value of the GPFS
\fBmaxBlockSize\fR configuration parameter. The
\fBmaxBlockSize\fR parameter is set to 1 MB by default. If a larger
block size is desired, use the \fBmmchconfig\fR command to increase the
\fBmaxBlockSize\fR prior to starting GPFS.
.RE
.PP
\fBResults\fR
.PP
Upon successful completion of the \fBmmcrfs\fR command, these tasks are
completed on all GPFS nodes:
.RS +3
.HP 3
\(bu 
Mount point directory is created.
.HP 3
\(bu 
File system is formatted.
.RE
.SH "Parameters"
.PP
.RS +3
\fB\fIMountpoint\fR
\fR
.RE
.RS +9
The mount point directory of the GPFS file system.
.RE
.PP
.RS +3
\fB\fIDevice\fR
\fR
.RE
.RS +9
The device name of the file system to be created.
.PP
File system names need not be fully-qualified. \fBfs0\fR is as
acceptable as \fB/dev/fs0\fR. However, file system names must be
unique within a GPFS cluster. Do not specify an existing entry in
\fB/dev\fR.
.RE
.PP
.RS +3
\fB-D {nfs4 | \fB\fIposix\fR\fR}
\fR
.RE
.RS +9
Specifies whether a 'deny-write open lock' will block writes,
which is expected and required by NFS V4. File systems supporting NFS
V4 must have \fB-D nfs4\fR set. The option \fB-D posix\fR allows
NFS writes even in the presence of a deny-write open lock. If you
intend to export the file system using NFS V4 or Samba, you must use \fB-D
nfs4\fR. For NFS V3 (or if the file system is not NFS exported at
all) use \fB-D posix\fR. The default is \fB-D posix\fR.
.RE
.PP
.RS +3
\fB-F \fIDescFile\fR
\fR
.RE
.RS +9
Specifies a file containing a list of disk descriptors, one per
line. You may use the rewritten \fIDiskDesc\fR file created by the
\fBmmcrnsd\fR command, create your own file, or enter the disk descriptors
on the command line. When using the \fIDiskDesc\fR file created by
the \fBmmcrnsd\fR command, the values supplied on input to the command for
\fIDisk Usage\fR and \fIFailureGroup \fR are used. When creating
your own file or entering the descriptors on the command line, you must
specify these values or accept the system defaults. A sample file can
be found in \fB/usr/lpp/mmfs/samples/diskdesc\fR.
.RE
.PP
.RS +3
\fB"\fIDiskDesc\fR[;\fIDiskDesc\fR...]"
\fR
.RE
.RS +9
A descriptor for each disk to be included. Each descriptor is
separated by a semicolon (;). The entire list must be enclosed in
quotation marks (' or "). 
.PP
The current maximum number of disk descriptors that can be defined for any
single file system is 268 million. However, to achieve this maximum
limit, you must recompile GPFS. The actual number of disks in your file
system may be constrained by products other than GPFS that you have
installed. Refer to the individual product documentation.
.PP
A disk descriptor is defined as (second, third and sixth fields
reserved):
.sp
.nf
DiskName:::DiskUsage:FailureGroup::StoragePool:
.fi
.sp
.PP
.RS +3
\fB\fIDiskName\fR
\fR
.RE
.RS +9
.PP
You must specify the name of the NSD previously created by the
\fBmmcrnsd\fR command. For a list of available disks, issue the
\fBmmlsnsd -F\fR command.
.RE
.PP
.RS +3
\fB\fIDiskUsage\fR
\fR
.RE
.RS +9
Specify a disk usage or accept the default:
.PP
.RS +3
\fBdataAndMetadata
\fR
.RE
.RS +9
Indicates that the disk contains both data and metadata. This is
the default.
.RE
.PP
.RS +3
\fBdataOnly
\fR
.RE
.RS +9
Indicates that the disk contains data and does not contain
metadata.
.RE
.PP
.RS +3
\fBmetadataOnly
\fR
.RE
.RS +9
Indicates that the disk contains metadata and does not contain
data.
.RE
.PP
.RS +3
\fBdescOnly
\fR
.RE
.RS +9
Indicates that the disk contains no data and no file metadata. Such
a disk is used solely to keep a copy of the file system descriptor, and can be
used as a third failure group in certain disaster recovery
configurations. For more information, see \fIGeneral Parallel File
System: Advanced Administration\fR and search on \fISynchronous
mirroring utilizing GPFS replication\fR.
.RE
.RE
.PP
.RS +3
\fB\fIFailureGroup\fR
\fR
.RE
.RS +9
A number identifying the failure group to which this disk belongs.
You can specify any value from -1 (where -1 indicates that the disk has no
point of failure in common with any other disk) to 4000. If you do not
specify a failure group, the value defaults to the primary server node number
plus 4000. If an NSD server node is not specified, the value defaults
to -1. GPFS uses this information during data and metadata placement to
assure that no two replicas of the same block are written in such a way as to
become unavailable due to a single failure. All disks that are attached
to the same NSD server or adapter should be placed in the same failure
group.
.PP
If replication of \fB-m\fR or \fB-r\fR is set to 2,
storage pools must have two failure groups for the commands to work
properly.
.RE
.PP
.RS +3
\fB\fIStoragePool\fR
\fR
.RE
.RS +9
Specifies the storage pool to which the disk is to be assigned. If
this name is not provided, the default is \fBsystem\fR.
.PP
Only the \fBsystem\fR pool may contain \fBdescOnly\fR,
\fBmetadataOnly\fR or \fBdataAndMetadata\fR disks.
.RE
.RE
.SH "Options"
.PP
.RS +3
\fB-A {\fB\fIyes\fR\fR | no | automount}
\fR
.RE
.RS +9
Indicates when the file system is to be mounted:
.PP
.RS +3
\fByes
\fR
.RE
.RS +9
When the GPFS daemon starts. This is the default.
.RE
.PP
.RS +3
\fBno
\fR
.RE
.RS +9
Manual mount.
.RE
.PP
.RS +3
\fBautomount
\fR
.RE
.RS +9
When the file system is first accessed.
.RE
.RE
.PP
.RS +3
\fB-B \fIBlockSize\fR
\fR
.RE
.RS +9
Size of data blocks. Must be 16 KB, 64 KB, 256 KB (the default),
512 KB, 1 MB, 2 MB, or 4 MB. Specify this value with the character
\fBK\fR or \fBM\fR, for example 512K.
.RE
.PP
.RS +3
\fB-E {\fB\fIyes\fR\fR | no}
\fR
.RE
.RS +9
Specifies whether to report \fIexact\fR \fBmtime\fR values (\fB-E
yes\fR), or to periodically update the \fBmtime\fR value for a file
system (\fB-E no\fR). If it is more desirable to display exact
modification times for a file system, specify or use the default \fB-E
yes\fR option.
.RE
.PP
.RS +3
\fB-j {cluster | scatter}
\fR
.RE
.RS +9
Specifies the block allocation map type. When allocating blocks for
a given file, GPFS first utilizes a round-robin algorithm to spread the
data across all disks in the file system. After a disk is selected, the
location of the data block on the disk is determined by the block allocation
map type. If \fBcluster\fR is specified, GPFS attempts to allocate
blocks in clusters. Blocks that belong to a given file are kept
adjacent to each other within each cluster. If \fBscatter\fR is
specified, the location of the block is chosen randomly.
.PP
The \fBcluster\fR allocation method may provide better disk performance
for some disk subsystems in relatively small installations. The
benefits of clustered block allocation diminish when the number of nodes in
the cluster or the number of disks in a file system increases, or when the
file system free space becomes fragmented. The \fBcluster\fR
allocation method is the default for GPFS clusters with eight or fewer nodes
or files systems with eight or fewer disks.
.PP
The \fBscatter\fR allocation method provides more consistent file system
performance by averaging out performance variations due to block location (for
many disk subsystems, the location of the data relative to the disk edge has a
substantial effect on performance). This allocation method is
appropriate in most cases and is the default for GPFS clusters with more than
eight nodes or file systems with more than eight disks.
.PP
The block allocation map type cannot be changed after the file system has
been created.
.RE
.PP
.RS +3
\fB\fB-k {\fR\fB\fIposix\fR\fR\fB | nfs4 | all}\fR
\fR
.RE
.RS +9
Specifies the type of authorization supported by the file system:
.PP
.RS +3
\fBposix
\fR
.RE
.RS +9
Traditional GPFS ACLs only (NFS V4 ACLs are not allowed).
Authorization controls are unchanged from earlier releases. The default
is \fB-k posix\fR.
.RE
.PP
.RS +3
\fBnfs4
\fR
.RE
.RS +9
Support for NFS V4 ACLs only. Users are not allowed to assign
traditional GPFS ACLs to any file system objects (directories and individual
files).
.RE
.PP
.RS +3
\fBall
\fR
.RE
.RS +9
Any supported ACL type is permitted. This includes traditional GPFS
(\fBposix\fR) and NFS V4 ACLs (\fBnfs4\fR).
.PP
The administrator is allowing a mixture of ACL types. For example,
\fBfileA\fR may have a \fBposix\fR ACL, while \fBfileB\fR in the same
file system may have an NFS V4 ACL, implying different access characteristics
for each file depending on the ACL type that is currently assigned.
.RE
.PP
Neither \fBnfs4\fR nor \fBall\fR should be specified here unless the
file system is going to be exported to NFS V4 clients. NFS V4 ACLs
affect file attributes (mode) and have access and authorization
characteristics that are different from traditional GPFS ACLs.
.RE
.PP
.RS +3
\fB-K {no | \fB\fIwhenpossible\fR\fR | always}
\fR
.RE
.RS +9
Specifies whether strict replication is to be enforced:
.PP
.RS +3
\fBno
\fR
.RE
.RS +9
Strict replication is not enforced. GPFS will try to create the
needed number of replicas, but will still return EOK as long as it can
allocate at least one replica.
.RE
.PP
.RS +3
\fBwhenpossible
\fR
.RE
.RS +9
Strict replication is enforced provided the disk configuration allows
it. If the number of failure groups is insufficient, strict replication
will not be enforced. This is the default value.
.RE
.PP
.RS +3
\fBalways
\fR
.RE
.RS +9
Strict replication is enforced.
.RE
.RE
.PP
.RS +3
\fB-m \fIDefaultMetadataReplicas\fR
\fR
.RE
.RS +9
Default number of copies of inodes, directories, and indirect blocks for a
file. Valid values are 1 and 2 but cannot be greater than the value of
\fIMaxMetadataReplicas\fR. The default is 1.
.RE
.PP
.RS +3
\fB -M \fIMaxMetadataReplicas\fR
\fR
.RE
.RS +9
Default maximum number of copies of inodes, directories, and indirect
blocks for a file. Valid values are 1 and 2 but cannot be less than
\fIDefaultMetadataReplicas\fR. The default is 1.
.RE
.PP
.RS +3
\fB-n \fINumNodes\fR
\fR
.RE
.RS +9
The estimated number of nodes that will mount the file system. This
is used as a best guess for the initial size of some file system data
structures. The default is 32. This value cannot be changed
after the file system has been created.
.PP
When you create a GPFS file system, you might want to overestimate the
number of nodes that will mount the file system. GPFS uses this
information for creating data structures that are essential for achieving
maximum parallelism in file system operations (see \fIAppendix A: GPFS
architecture\fR in \fIGeneral Parallel File System: Concepts,
Planning, and Installation Guide\fR). Although a large estimate
consumes additional memory, underestimating the data structure allocation can
reduce the efficiency of a node when it processes some parallel requests such
as the allotment of disk space to a file. If you cannot predict the
number of nodes that will mount the file system, allow the default value to be
applied. If you are planning to add nodes to your system, you should
specify a number larger than the default. However, do not make
estimates that are not realistic. Specifying an excessive number of
nodes may have an adverse affect on buffer operations.
.RE
.PP
.RS +3
\fB-N \fINumInodes\fR[:\fINumInodesToPreallocate\fR]
\fR
.RE
.RS +9
The \fINumInodes\fR parameter specifies the maximum number of files in
the file system. This value defaults to the size of the file system at
creation, divided by 1M and is also constrained by the formula:
.PP
\fBmaximum number of files = (total file system space/2) / (inode size +
subblock size)\fR
.PP
For file systems that will be doing parallel file creates, if the total
number of free inodes is not greater than 5% of the total number of inodes
there is the potential for slowdown in file system access. Take this
into consideration when creating your file system.
.PP
The parameter \fINumInodesToPreallocate\fR specifies the number of
inodes that the system will immediately preallocate. If you do not
specify a value for \fINumInodesToPreallocate\fR, GPFS will dynamically
allocate inodes as needed
.PP
You can specify the \fINumInodes\fR and \fINumInodesToPreallocate\fR
values with a suffix, for example 100K or 2M.
.RE
.PP
.RS +3
\fB-Q {yes | \fB\fIno}\fR\fR
\fR
.RE
.RS +9
Activates quotas automatically when the file system is mounted. The
default is \fB-Q no\fR.
.PP
To activate GPFS quota management after the file system has been
created: 
.RS +3
.HP 3
1. Mount the file system.
.HP 3
2. To establish default quotas:
.RS +3
.HP 3
a. Issue the \fBmmdefedquota\fR command to establish default quota
values.
.HP 3
b. Issue the \fBmmdefquotaon\fR command to activate default quotas.
.RE
.HP 3
3. To activate explicit quotas:
.RS +3
.HP 3
a. Issue the \fBmmedquota\fR command to activate quota values.
.HP 3
b. Issue the \fBmmquotaon\fR command to activate quota enforcement.
.RE
.RE
.RE
.PP
.RS +3
\fB-r \fIDefaultDataReplicas\fR
\fR
.RE
.RS +9
Default number of copies of each data block for a file. Valid
values are 1 and 2, but cannot be greater than
\fIMaxDataReplicas\fR. The default is 1.
.RE
.PP
.RS +3
\fB-R \fIMaxDataReplicas\fR
\fR
.RE
.RS +9
Default maximum number of copies of data blocks for a file. Valid
values are 1 and 2 but cannot be less than
\fIDefaultDataReplicas\fR. The default is 1.
.RE
.PP
.RS +3
\fB-S {yes | \fB\fIno\fR\fR}
\fR
.RE
.RS +9
Suppress the periodic updating of the value of \fBatime\fR as reported
by the \fBgpfs_stat()\fR, \fBgpfs_fstat()\fR, \fBstat()\fR, and
\fBfstat()\fR calls. The default value is \fB-S no\fR.
Specifying \fB-S yes\fR for a new file system results in reporting the time
the file system was created.
.RE
.PP
.RS +3
\fB-v {\fB\fIyes\fR\fR | no}
\fR
.RE
.RS +9
Verify that specified disks do not belong to an existing file
system. The default is \fB-v yes\fR. Specify \fB-v no\fR
only when you want to reuse disks that are no longer needed for an existing
file system. If the command is interrupted for any reason, you must use
the \fB-v no\fR option on the next invocation of the command.
.RE
.PP
.RS +3
\fB-z {\fByes\fR | \fB\fIno\fR\fR}
\fR
.RE
.RS +9
Enable or disable DMAPI on the file system. The default is \fB-z
no\fR. For further information on DMAPI for GPFS, see \fIGeneral
Parallel File System: Data Management API Guide\fR.
.RE
.SH "Exit status"
.PP
.PP
.RS +3
\fB0
\fR
.RE
.RS +9
Successful completion.
.RE
.PP
.RS +3
\fBnonzero
\fR
.RE
.RS +9
A failure has occurred.
.RE
.SH "Security"
.PP
You must have root authority to run the \fBmmcrfs\fR command.
.PP
You may issue the \fBmmcrfs\fR command from any node in the GPFS
cluster.
.PP
When using the \fBrcp\fR and \fBrsh\fR commands for remote
communication, a properly configured \fB.rhosts\fR file must exist
in the root user's home directory on each node in the GPFS
cluster. If you have designated the use of a different remote
communication program on either the \fBmmcrcluster\fR or the
\fBmmchcluster\fR command, you must ensure:
.RS +3
.HP 3
1. Proper authorization is granted to all nodes in the GPFS cluster.
.HP 3
2. The nodes in the GPFS cluster can communicate without the use of a
password, and without any extraneous messages.
.RE
.PP
When considering data replication for files accessible to SANergy, see
\fISANergy export considerations\fR in \fIGeneral Parallel File
System: Advanced Administration Guide\fR.
.SH "Examples"
.PP
This example creates a file system named \fBgpfs1\fR, using three disks,
with a block size of 512 KB, allowing metadata and data replication to be 2
and turning quotas on:
.sp
.nf
mmcrfs /gpfs1 gpfs1 "hd3vsdn100;sdbnsd;sdensd" -B 512K -M 2 -R 2 -Q yes
.fi
.sp
.PP
The system displays output similar to:
.sp
.nf
The following disks of gpfs1 will be formatted on node k5n95.kgn.ibm.com:
hd3vsdn100: size 17760256 KB
sdbnsd: size 70968320 KB
sdensd: size 70968320 KB
Formatting file system ...
Disks up to size 208 GB can be added to storage pool system.
Creating Inode File
Creating Allocation Maps
Clearing Inode Allocation Map
Clearing Block Allocation Map
Completed creation of file system /dev/gpfs1.mmcrfs:\ 
Propagating the cluster configuration data to allaffected nodes.\ 
This is an asynchronous process.
.fi
.sp
.SH "See also"
.PP
mmchfs Command
.PP
mmdelfs Command
.PP
mmdf Command
.PP
mmedquota Command
.PP
mmfsck Command
.PP
mmlsfs Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR