Managing HP X9000 Native Filesystem Snapshots Application Note (TA768-96048, October 2011)

Space utilization
Space used by snapshots is included in the used capacity of the file system and in user quotas. There
are currently no tools to determine the space used by a specific snapshot. Standard file system space
reporting utilities work as follows:
• The ls and du commands report the size of a file depending on whether you are viewing a
snapshot or the current version of a file. If you are looking at a snapshot, the commands report
the size of the file when it was snapped. If you are looking at the current version of the file, the
commands report the current size.
• The df command reports the total file system space used by files and snapshots.
Accessing snapshot directories
Snapshots are stored in a read-only directory named .snapshot, which is located under the directory
tree. For example, snapshots for directory tree /ibfs1/users are stored in the /ibfs1/users/
.snapshot directory. Each snapshot is a separate directory beneath the .snapshot directory.
Snapshots are named automatically using the ISO 8601 date and time format, plus a custom value.
For example, a snapshot created on June 1, 2011 at 9 a.m. is named 2011-06-01T090000_<name>.
For snapshots created automatically, <name> is hourly, daily, weekly, or monthly. If you create
the snapshot on-demand, you can specify the <name>.
The following example lists snapshots created on an hourly schedule for snap tree /ibfs1/users.
Using ISO 8601 naming ensures that the snapshot directories appear in the order in which they were
taken.
[root@x9000n1 ~]# # cd /ibfs1/users/.snapshot/
[root@x9000n1 .snapshot]# ls
2011-06-01T110000_hourly 2011-06-01T190000_hourly 2011-06-02T030000_hourly
2011-06-01T120000_hourly 2011-06-01T200000_hourly 2011-06-02T040000_hourly
2011-06-01T130000_hourly 2011-06-01T210000_hourly 2011-06-02T050000_hourly
2011-06-01T140000_hourly 2011-06-01T220000_hourly 2011-06-02T060000_hourly
2011-06-01T150000_hourly 2011-06-01T230000_hourly 2011-06-02T070000_hourly
2011-06-01T160000_hourly 2011-06-02T000000_hourly 2011-06-02T080000_hourly
2011-06-01T170000_hourly 2011-06-02T010000_hourly 2011-06-02T090000_hourly
2011-06-01T180000_hourly 2011-06-02T020000_hourly
Users with access to the root of the snapshot directory tree (in this example, /ibfs1/users/) can
navigate to the /ibfs1/users/.snapshot directory, view snapshots, and copy all or part of a
snapshot. If necessary, users can copy a snapshot and overlay the present copy to achieve manual
rollback.
NOTE: Access to .snapshot directories is limited to administrators and NFS and CIFS users.
Accessing snapshots using NFS
Access over NFS is similar to local X9000 access except that the mount point is probably different.
In this example, NFS export /ibfs1/users is mounted as /users1 on an NFS client.
[root@rhel5vm1 ~]# cd /users1/.snapshot
[root@rhel5vm1 .snapshot]# ls
2011-06-01T110000_hourly 2011-06-01T150000_hourly 2011-06-01T190000_hourly
2011-06-01T120000_hourly 2011-06-01T160000_hourly 2011-06-01T200000_hourly
2011-06-01T130000_hourly 2011-06-01T170000_hourly
2011-06-01T140000_hourly 2011-06-01T180000_hourly
Accessing snapshots using CIFS
Windows users can use Explorer to navigate to the .snapshot folder and view files. In the following
example, /ibfs1/users/ is mapped to the Y drive on a Windows system.
4 Accessing snapshot directories