Storage Foundation 7.4.1 Administrator's Guide - Linux

Displaying instant snapshot information

The vxsnap print command may be used to display information about the snapshots that are associated with a volume.

# vxsnap [-g diskgroup] print [vol]

This command shows the percentage progress of the synchronization of a snapshot or volume. If no volume is specified, information about the snapshots for all the volumes in a disk group is displayed. The following example shows a volume, vol1, which has a full-sized snapshot, snapvol1 whose contents have not been synchronized with vol1:

# vxsnap -g mydg print
NAME     SNAPOBJECT     TYPE    PARENT   SNAPSHOT   %DIRTY   %VALID

vol1     --             volume  --       --         --       100
         snapvol1_snp1  volume  --       snapvol1   1.30     --
snapvol1 vol1_snp1      volume  vol1     --         1.30     1.30

The %DIRTY value for snapvol1 shows that its contents have changed by 1.30% when compared with the contents of vol1. As snapvol1 has not been synchronized with vol1, the %VALID value is the same as the %DIRTY value. If the snapshot were partly synchronized, the %VALID value would lie between the %DIRTY value and 100%. If the snapshot were fully synchronized, the %VALID value would be 100%. The snapshot could then be made independent or moved into another disk group.

Additional information about the snapshots of volumes and volume sets can be obtained by using the -n option with the vxsnap print command:

# vxsnap [-g diskgroup] -n [-l] [-v] [-x] print [vol]

Alternatively, you can use the vxsnap list command, which is an alias for the vxsnap -n print command:

# vxsnap [-g diskgroup] [-l] [-v] [-x] list [vol]

The following output is an example of using this command on the disk group dg1:

# vxsnap -g dg -vx list

NAME   DG    OBJTYPE SNAPTYPE  PARENT  PARENTDG  SNAPDATE        CHANGE_DATA    SYNCED_DATA
vol    dg1   vol     -         -       -         -        -                     10G (100%)
svol1  dg2   vol     fullinst  vol     dg1       2006/2/1 12:29  20M (0.2%)     60M (0.6%)
svol2  dg1   vol     mirbrk    vol     dg1       2006/2/1 12:29  120M (1.2%)    10G (100%)
svol3  dg2   vol     volbrk    vol     dg1       2006/2/1 12:29  105M (1.1%)    10G (100%)
svol21 dg1   vol     spaceopt  svol2   dg1       2006/2/1 12:29  52M (0.5%)     52M (0.5%)
vol-02 dg1   plex    snapmir   vol     dg1       -               -              56M (0.6%)
mvol   dg2   vol     mirvol    vol     dg1       -               -              58M (0.6%)
vset1  dg1   vset    -     -   -       -         -                              2G (100%)
v1     dg1   compvol -     -   -       -         -                              1G (100%)
v2     dg1   compvol -     -   -       -         -                              1G (100%)
svset1 dg1   vset    mirbrk    vset    dg1       2006/2/1 12:29  1G (50%)       2G (100%)
sv1    dg1   compvol mirbrk    v1      dg1       2006/2/1 12:29  512M (50%)     1G (100%)
sv2    dg1   compvol mirbrk    v2      dg1       2006/2/1 12:29  512M (50%)     1G (100%)
vol-03 dg1   plex    detmir    vol     dg1       -               20M (0.2%)     -
mvol2  dg2   vol     detvol    vol     dg1       -               20M (0.2%)     -

This shows that the volume vol has three full-sized snapshots, svol1, svol2 and svol3, which are of types full-sized instant (fullinst), mirror break-off (mirbrk) and linked break-off (volbrk). It also has one snapshot plex (snapmir), vol-02, and one linked mirror volume (mirvol), mvol. The snapshot svol2 itself has a space-optimized instant snapshot (spaceopt), svol21. There is also a volume set, vset1, with component volumes v1 and v2. This volume set has a mirror break-off snapshot, svset1, with component volumes sv1 and sv2. The last two entries show a detached plex, vol-03, and a detached mirror volume, mvol2, which have vol as their parent volume. These snapshot objects may have become detached due to an I/O error, or, in the case of the plex, by running the vxplex det command.

The CHANGE_DATA column shows the approximate difference between the current contents of the snapshot and its parent volume. This corresponds to the amount of data that would have to be resynchronized to make the contents the same again.

The SYNCED_DATA column shows the approximate progress of synchronization since the snapshot was taken.

The -l option can be used to obtain a longer form of the output listing instead of the tabular form.

The -x option expands the output to include the component volumes of volume sets.

See the vxsnap(1M) manual page for more information about using the vxsnap print and vxsnap list commands.