Volume Tips and Tasks

The basic command used to create volumes is "vxassist". The format is "vxassist make". The length can be specified in units of kilobytes, megabytes, or gigabytes with the suffixes k, m, or g. By default, new volumes are created from rootdg. Use "-g" to specify a different diskgroup.

To determine the maximum size that a new volume could be given particular attributes, use the "vxassist maxsize" command. For example, to determine the maximum size of a striped volume using disk01 and disk02:

vxassist maxsize layout=stripe disk01 disk02

Then create the volume using that length. For example: vxassist make vol01 20g layout=stripe disk01 disk02

By default, the "vxassist" command creates concatenated volumes. For example, the command "vxassist make newvol 10m" would create a concatenated volume with the length of 10 MB. To specify the disk(s) to use, add the disk name(s). For example, "vxassist make newvol 10m disk01".

To create striped volumes, add the attribute "layout=stripe". For exampke, "vxassist make newvol 10g layout=stripe disk01 disk02".

To create RAID-5 volumes, add the attribute "layout=raid5". For example, "vxassist make newvol 30g layout=raid5".

To create mirrored volumes, add the attribute "layout=mirror". For example, "vxassist make newvol 10g layout=mirror".

The "vxassist" command can be used to grow or shrink the size of volumes. Do not shrink the size of volumes below the size of the filesystem. To grow volumes, run one of the following commands:

vxassist growto
vxassist growby

Similarly, you can shrink the size of volumes:

vxassist shrinkto
vxassist shrinkby

To remove an unneeded volume, unmount any filesystems on the volume, remove any references to the volume from /etc/vfstab, stop the volume with "vxvol stop", and then run "vxedit -rf rm" or "vxassist remove volume".

Existing volumes can be mirrored to add redundancy. To mirror existing volumes, use the following command:

vxassist mirror

To remove a mirror (more precisely, to remove one of the plexes from the volume), use the following command:

vxplex -o rm

To stop volumes, use the command "vxvol stop". To stop all volumes, run the command "vxvol stopall". To restart volumes, use the command "vxrecover -s" or use the command Veritas will automatically allocate the necessary space from unused disks. The process may take some time depending on the size of the volume. When fully synchronized, the status of the snapshot mirror will change to SNAPDONE. Use the following command to monitor the progress of the snapshot:

vxtask -l list

2. Detach the snapshot and create the new read-only snapshot volume with the following command:

vxassist snapshot

The period required to create the snapshot volume is shorter but it is preferred to limit I/O to the volume during the period required.

3. Clean the contents of the new snapshot volume with the following command:

fsck -y /dev/vx/rdsk/

4. Mount the snapshot volume, perform the backup, unmount the volume, and then remove the snapshot volume to save space with the following command:

vxedit -rf rm