.TH mmsnapdir 12/04/06
mmsnapdir Command
.SH "Name"
.PP
\fBmmsnapdir\fR - Creates and deletes invisible directories that connect to
the snapshots of a GPFS file system, and changes the name of the snapshots
subdirectory.
.SH "Synopsis"
.PP
\fBmmsnapdir\fR \fIDevice\fR {[\fB-r\fR | \fB-a\fR]
[\fB-s\fR \fISnapDirName\fR]}
.PP
Or,
.PP
\fBmmsnapdir\fR \fIDevice\fR [\fB-q\fR]
.SH "Description"
.PP
Use the \fBmmsnapdir\fR command to create or delete invisible
directories that connect to the snapshots of a GPFS file system, and change
the name of the snapshots subdirectory.
.PP
Snapshots appear in a subdirectory in the root directory of the file
system. If you prefer to access the snapshots from each file system
directory rather than traversing through the root directory, you may create an
invisible directory to make the connection by issuing the \fBmmsnapdir\fR
command with the \fB-a\fR flag (see Example 1). The \fB-a\fR flag of the \fBmmsnapdir\fR
command creates an invisible directory in each normal directory in the active
file system (they do not appear in directories in snapshots) that contains a
subdirectory for each existing snapshot of the file system. These
subdirectories correspond to the copy of the that directory in the snapshot
with the same name.
.PP
If the \fBmmsnapdir\fR command is issued while another snapshot command
is running, the \fBmmsnapdir\fR command waits for that command to
complete.
.PP
For more information about GPFS snapshots, see \fICreating and maintaining
snapshots of GPFS file systems\fR in \fIGeneral Parallel File
System: Advanced Administration Guide\fR.
.SH "Parameters"
.PP
.RS +3
\fB\fIDevice\fR
\fR
.RE
.RS +9
The device name of the file system. File system names need not be
fully-qualified. \fBfs0\fR is just as acceptable as
\fB/dev/fs0\fR.
.PP
This must be the first parameter.
.RE
.SH "Options"
.PP
.PP
.RS +3
\fB-a 
\fR
.RE
.RS +9
Adds a snapshots subdirectory to all subdirectories in the file
system.
.RE
.PP
.RS +3
\fB-q
\fR
.RE
.RS +9
Displays current settings, if issued without any other flags.
.RE
.PP
.RS +3
\fB-r
\fR
.RE
.RS +9
Reverses the effect of the \fB-a\fR option. All invisible
snapshot directories are removed. The snapshot directory under the file
system root directory is not affected.
.RE
.PP
.RS +3
\fB-s \fISnapDirName\fR
\fR
.RE
.RS +9
Changes the name of the snapshots subdirectory to
\fISnapDirName\fR. This affects both the directory in the file
system root as well as the invisible directory in the other file system
directories if the \fBmmsnapdir -a\fR command has been issued.
.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
If you are a root user, you may issue the \fBmmsnapdir\fR command from
any node in the GPFS cluster.
.PP
You must be a root user to use the \fB-a\fR, \fB-r\fR,
and \fB-s\fR options.
.PP
If you are a non-root user, you may only specify file systems that
belong to the same cluster as the node on which the \fBmmsnapdir\fR command
was issued.
.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
.SH "Examples"
.RS +3
.HP 3
1. To rename the \fB.snapshots\fR directory (the
default snapshots directory name) to \fB.link\fR for file system
\fBfs1\fR, issue the command: 
.sp
.nf
mmsnapdir  fs1 -s .link
.fi
.sp
.sp
After the command has been issued, the directory structure would appear
similar to:
.sp
.nf
/fs1/file1
/fs1/userA/file2
/fs1/userA/file3
/fs1/.link/snap1/file1
/fs1/.link/snap1/userA/file2
/fs1/.link/snap1/userA/file3
.fi
.sp
.HP 3
2. Issuing:
.sp
.nf
mmsnapdir fs1 -a
.fi
.sp
After the command has been issued, the directory structure would appear
similar to:
.sp
.nf
/fs1/file1
/fs1/userA/file2
/fs1/userA/file3
/fs1/userA/.link/snap1/file2
/fs1/userA/.link/snap1/file3
/fs1/.link/snap1/file1
/fs1/.link/snap1/userA/file2
/fs1/.link/snap1/userA/file3
.fi
.sp
.sp
The \fB.link\fR subdirectory under the root directory and under
each subdirectory of the tree provides two different paths to each snapshot
copy of a file. For example,
\fB/fs1/userA/.link/snap1/file2\fR and
\fB/fs1/.link/snap1/userA/file2\fR are two different paths that
access the same snapshot copy of \fB/fs1/userA/file2\fR.
.HP 3
3. Issuing:
.sp
.nf
mmsnapdir fs1 -r
.fi
.sp
After the command has been issued, the directory structure would appear
similar to:
.sp
.nf
/fs1/file1
/fs1/userA/file2
/fs1/userA/file3
/fs1/.link/snap1/file1
/fs1/.link/snap1/userA/file2
/fs1/.link/snap1/userA/file3
.fi
.sp
.HP 3
4. Issuing:
.sp
.nf
mmsnapdir fs1 -q
.fi
.sp
The output is similar to this:
.sp
.nf
Snapshot directory for "fs1" is ".link" (root directory only)
.fi
.sp
.RE
.SH "See also"
.PP
mmcrsnapshot Command
.PP
mmdelsnapshot Command
.PP
mmlssnapshot Command
.PP
mmrestorefs Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR