HP X9000 File System Software Snapshots Application Note for X9000 File Serving Software 6.0 or later Abstract This document describes the X9000 file system software snapshot feature, and is intended for Storage Administrators and Windows Administrators. An understanding of X9000 systems is required and general knowledge of software snapshots is useful.
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Overview The X9000 software snapshot feature allows you to capture a point-in-time copy of a file system or directory. Snapshots are taken at the directory level. You can take snapshots of up to 1024 directories per X9000 file system, and up to 1024 snapshots can be taken of each directory. An X9000 system supports up to 255 file systems. Although snapshots are managed at the directory level, they are implemented per file.
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.
Managing snapshots with the CLI Use the ibrix_snap and ibrix_snapreclamation commands to manage snapshots. You cannot use the CLI to create schedules for snapshots or snapshot reclamation tasks.
Deleting a snapshot Use ibrix_snap -d to delete a snapshot: [root@x9000n1 ~]# ibrix_snap -d -f ibfs1 -P /ibfs1/users -n 2011-05-31T143154_snap1 Deleting native snapshot 2011-05-31T143154_snap1 on file system ibfs1 The response is: deleteSnapshot Success Command succeeded! Deleting a snapshot does not free the space used by the snapshot. You must run a snapshot space reclamation task to reclaim the space.
To add a new snap tree, click Add on the Snap Trees panel. On the Add Snap Tree dialog box, select the file system and enter the directory path that you want to make snapable. (The directory path defaults to the root of the file system.) To define a snapshot schedule, check Schedule the creation of snapshots and then specify the frequency and number of snapshots to keep. This example specifies a directory path and uses the default values for the schedule.
You can add, modify, or delete a schedule by selecting the appropriate snap tree on the Snap Trees panel and clicking Modify. Viewing snapshots To view the snapshots for a specific directory tree, select the appropriate snap tree on the Snap Trees panel, and then select Snapshots from the lower Navigator. The Snapshots panel lists snapshots for the selected directory tree. Use the filter at the bottom of the Snapshots panel to select the snapshots you want to view.
Creating an on-demand snapshot Select the appropriate snap tree from the Snap Trees panel. In the lower Navigator, select Snapshots, and then click Create on the Snapshots panel. On the Create Snapshot dialog box, enter a name for the snapshot. When you click OK, a status window appears. Review this window for any errors. The snapshot you created appears on the Snapshots pane on the GUI.
Click New on the Task Summary panel. On the New Space Reclamation Task dialog box, select a reclamation strategy. The default is Maximum Space Reclaimed. Reclamation tasks using the Maximum Space Reclaimed strategy can be run on demand, or you can define a schedule for the task on the Schedule tab.
Reclamation tasks using the using the Maximum Speed strategy can be run on demand only. Compatibility with other X9000 software features Tiering If a file is migrated between tiers, all blocks occupied by the file and its snapshots move to the new tier. The view in .snapshots does not change. Segment rebalancing and segment evacuation Files and their snapshots move together. Remote replication Use Run Once replication to replicate individual snapshots.
If you replicate a snapshot of the same directory or file system to the same destination at a later time, only the differences between the two snapshots are sent. This makes it possible to maintain a point-in-time copy of a directory or file system at two sites. You can create a local snapshot of the copy at the remote site. NOTE: The Continuous remote replication mode does not replicate snapshots. It replicates the current version of files in the source directory and skips the .snapshot directory.
