Creating a logical volume to be used as a snap

[Joan Blais]

I have a system with "vault" logical volumes that are 8 Gb and "snap" logical volumes that are 1 GB in size. There is a command to create this special "snap" lv. Does anyone know what that is?
Thanks,
Joan

[RAC_1 · Accepted solution]

Are you looking at following??

mount -F vxfs -o snapof=original_lv "/dev/vgxx/lv_name_of_snap_lvol /mount_point

Anil

[A. Clay Stephenson]

You seem to be referring to vxfs snapshot mounts; the snapshot buffer (an additional logical volume that is created just like any other LVOL) is used to store the first changes of any block in the original filesystem. That is why the "snap" LVOL can be so much smaller than the original filesystem LVOL. The "snapshot" is a composite of all the unchanged blocks in the original filesystem and the changed blocks read from the snapshot buffer.

Man mount_vxfs for deatils and look for the snapof= option.

[Steven E. Protter]

lvecreate -n orb1 /dev/vg02
lvextend -l 502 /dev/vg02/orb2 /dev/dsk/c5t8d0

Then the command in response 1.

SEP

[Zinky]

You can use either an existing Filesystem or a new LVOL for your snapshot. If you do a lot of changes to the snapped filesystem - then you need to make sure you've enough space on your snapof storage. Snap filesystems are often used during Oracle backups to take on changes to the filesystems while the original mounts are being backed up or copied. Once released.. the changes are re-applied back to the original filesystems.

VxFS (Veritas filesystem or Onlione JFS) was the first to incorporate this. Other Unix Filesystems also offer the same features...

[Joan Blais]

It's coming back to me now. I have scripted the commands for the snaps-
mount -F vxfs -o snapof=/vault_plmprd8 /dev/vgexe/lvsnap8 /snap8 ...etc. all vaults and snaps associated.
Thanks to all.
Joan

[Joan Blais]

mount -F vxfs -o snapof=/mountpoint /dev/vgxx/lvxx /snapmountpoint