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Storage Foundation 7.4.1 Administrator's Guide - Linux

Last Published: 2019-09-25

Product(s): InfoScale & Storage Foundation (7.4.1)

Platform: Linux

Accessing a Storage Checkpoint

You can mount Storage Checkpoints using the mount command with the mount option -o ckpt=ckpt_name.

See the mount_vxfs(1M) manual page.

Observe the following rules when mounting Storage Checkpoints:

Storage Checkpoints are mounted as read/write Storage Checkpoints by default.
If a Storage Checkpoint is currently mounted as a read-only Storage Checkpoint, you can remount it as a writable Storage Checkpoint using the -o remount option.
To mount a Storage Checkpoint of a file system, first mount the file system itself.
To unmount a file system, first unmount all of its Storage Checkpoints.

Warning:

If you create a Storage Checkpoint for backup purposes, do not mount it as a writable Storage Checkpoint. You will lose the point-in-time image if you accidently write to the Storage Checkpoint.

If older Storage Checkpoints already exist, write activity to a writable Storage Checkpoint can generate copy operations and increased space usage in the older Storage Checkpoints.

A Storage Checkpoint is mounted on a special pseudo device. This pseudo device does not exist in the system name space; the device is internally created by the system and used while the Storage Checkpoint is mounted. The pseudo device is removed after you unmount the Storage Checkpoint. A pseudo device name is formed by appending the Storage Checkpoint name to the file system device name using the colon character (:) as the separator.

For example, if a Storage Checkpoint named may_23 belongs to the file system residing on the special device /dev/vx/dsk/fsvol/vol1, the Storage Checkpoint pseudo device name is:

  /dev/vx/dsk/fsvol/vol1:may_23

To mount the Storage Checkpoint named may_23 as a read-only Storage Checkpoint on directory /fsvol_may_23, type:
```
  # mount -t vxfs -o ckpt=may_23 /dev/vx/dsk/fsvol/vol1:may_23 \
  /fsvol_may_23
```
Note:
The vol1 file system must already be mounted before the Storage Checkpoint can be mounted.

To remount the Storage Checkpoint named may_23 as a writable Storage Checkpoint, type:

  # mount -t vxfs -o ckpt=may_23,remount,rw \
  /dev/vx/dsk/fsvol/vol1:may_23 /fsvol_may_23

To mount this Storage Checkpoint automatically when the system starts up, put the following entries in the /etc/fstab file:

  Device-Special-File  Mount-Point    fstype  options     backup-    pass-
                                                          frequency  number
  /dev/vx/dsk/fsvol/   /fsvol         vxfs    defaults    0          0
    vol1
  /dev/vx/dsk/fsvol/   /fsvol_may_23  vxfs    ckpt=may_23 0          0
    vol1:may_23

To mount a Storage Checkpoint of a cluster file system, you must also use the -o cluster option:
```
  # mount -t vxfs -o cluster,ckpt=may_23 \
  /dev/vx/dsk/fsvol/vol1:may_23 /fsvol_may_23
```
You can only mount a Storage Checkpoint cluster-wide if the file system that the Storage Checkpoint belongs to is also mounted cluster-wide. Similarly, you can only mount a Storage Checkpoint locally if the file system that the Storage Checkpoint belongs to is mounted locally.

You can unmount Storage Checkpoints using the umount command.

See the umount(1M) manual page.

Storage Checkpoints can be unmounted by the mount point or pseudo device name:

  # umount /fsvol_may_23 
  # umount /dev/vx/dsk/fsvol/vol1:may_23

Note:

You do not need to run the fsck utility on Storage Checkpoint pseudo devices because pseudo devices are part of the actual file system.