Veritas Volume Manager – Preparing a Volume for Online Backup

10. Preparing a Volume for Online Backup

Volume manager provides an easy way to take backup of the online data by creating an offline snapshot mirror of the volume .

The vxassist snapstart operation creates a write-only backup mirror, which is attached to and synchronized with the volume to be backed up and later detached and made offline by vxassist snapshot command . The snapshot volume can be used by backup utilities while the original volume continues to be available for applications and users.

The volume backup method described here does not apply to RAID-5 volumes.

Backing up a volume with vxassist involves the following procedure

Create a snapshot mirror

snapstart starts creating a online snapshot mirror of the volume using the available disk space . The snapshot is completed with vxassist snapshot command when offline snapshot volume is created with a userdefined name .

Command Syntax

* vxassist snapstart volume_name

To create a snapshot mirror of a volume called vol8, type

* #vxassist snapstart vol8

Create a snapshot volume

Command Syntax

vxassist snapshot volume_name new_volume_name

To create a snapshot volume of vol8, type:
#vxassist snapshot vol8 snapvol8

You can now back up the snapshot volume by whatever means you prefer. To avoid wasting space, you can then remove the snapshot volume, which occupies as much space as the original volume

11 Displaying Volume Configuration Information

The vxprint command can be used to display information about how a volume is configured.

Display the volume, mirror, and subdisk record information for all volumes as follows:

#vxprint -ht

Disk group: rootdg


 Disk group: rootdg DG NAME NCONFIG NLOG MINORS GROUP-ID DM NAME DEVICE TYPE PRIVLEN PUBLEN STATE V NAME USETYPE KSTATE STATE LENGTH READPOL PREFPLEX PL NAME VOLUME KSTATE STATE LENGTH LAYOUT NCOL/WID MODE SD NAME PLEX DISK DISKOFFS LENGTH [COL/]OFF DEVICE MODE dg rootdg 759096729.1025.tweety dm disk10 c1t0d0s2 sliced 559 1044400 - dm disk20 c2t0d0s2 sliced 559 1044400 - v pubs fsgen ENABLED ACTIVE 2288 SELECT - pl pubs-01 pubs ENABLED ACTIVE 2288 CONCAT - RW sd disk10-01 pubs-01 disk10 0 2288 0 c0t0d0 ENA v vol8 fsgen ENABLED ACTIVE 20480 SELECT - pl vol8-01 vol8 ENABLED ACTIVE 20480 CONCAT - RW sd disk10-02 vol8-0 disk10 2288 20480 0 c0t1d0 ENA 

where dg is a disk group, dm is a disk,
v is a volume,
pl is a plex,
sd is a subdisk.
The top few lines indicate the headers that match each type of output line that follows.
Each volume is listed along with its associated plex(es) and subdisk(s).
Display volume-related information for a specific volume as follows:

#vxprint -t volume_name
To display information about vol8, type:

#vxprint -t vol8