Veritas InfoScale™ 7.4 Solutions Guide - Solaris

To make a full-sized instant snapshot for a backup of an online database on the same host

1. Use the following commands to add one or more snapshot plexes to the volume, and to make a full-sized break-off snapshot, snapvol, of the tablespace volume by breaking off these plexes:

   # vxsnap -g database_dg addmir database_vol [nmirror=N] \
     [alloc=storage_attributes]
   # vxsnap -g database_dg make \
     source=database_vol/newvol=snapvol[/nmirror=N]\
     [alloc=storage_attributes]

   By default, one snapshot plex is added unless you specify a number using the nmirror attribute. For a backup, you should usually only require one plex. You can specify storage attributes (such as a list of disks) to determine where the plexes are created.

   You can specify at least N number of disks if the specified number of mirrors is N.

2. If the volume layout does not support plex break-off, prepare an empty volume for the snapshot. Create a full-sized instant snapshot for an original volume that does not contain any spare plexes, you can use an empty volume with the required degree of redundancy, and with the same size and same region size as the original volume.

   Use the vxprint command on the original volume to find the required size for the snapshot volume.

   # LEN='vxprint [-g diskgroup] -F%len database_vol'

   Note:

   The command shown in this and subsequent steps assumes that you are using a Bourne-type shell such as sh, ksh or bash. You may need to modify the command for other shells such as csh or tcsh. These steps are valid only for instant snap DCOs.

3. Use the vxprint command on the original volume to discover the name of its DCO:

   #  DCONAME='vxprint [-g diskgroup] -F%dco_name database_vol'

4. Use the vxprint command on the DCO to discover its region size (in blocks):

   # RSZ='vxprint [-g diskgroup] -F%regionsz $DCONAME'

5. Use the vxassist command to create a volume, snapvol, of the required size and redundancy. You can use storage attributes to specify which disks should be used for the volume. The init=active attribute makes the volume available immediately.

   # vxassist [-g diskgroup] make snapvol $LEN \
     [layout=mirror nmirror=number] init=active \
     [storage_attributes]

6. Prepare the snapshot volume for instant snapshot operations as shown here:

   # vxsnap [-g diskgroup] prepare snapvol [ndcomirs=number] \
     regionsz=$RSZ [storage_attributes]

   It is recommended that you specify the same number of DCO mirrors (ndcomirror) as the number of mirrors in the volume (nmirror).

7. Use the following command to create the snapshot:

   # vxsnap -g database_dg make source=database_vol/snapvol=snapvol

   If a database spans more than one volume, specify all the volumes and their snapshot volumes as separate tuples on the same line, for example:

   # vxsnap -g database_dg make source=database_vol1/snapvol=snapvol1 \
   source=database_vol2/newvol=snapvol2 \
   source=database_vol3/snapvol=snapvol3

   When you are ready to make a backup, proceed to make a backup of an online database on the same host.