Adding space in layered volumes..
We have a volume which has two plexes each plex has LUN's from storages in different datacentre(DC). This was done to avoid a situation that even if storage in one DC fails the data will be availa...
- SaGu,
yes you have hit a classic problem and the approach in the manuals is too theoretical. In the real world you do not use a volume extension command or conversion or even use vxassist with an ordered option. This is because the command line is atomic and too complicated and you are operating on live data. In all probability you will make an error and the conversion or extension will commence putting the data on the wrong luns meaning you will have to clean up these records before you can re-commence.
First what you need is enough luns on each data store to build a temporary provisional volume. I assume you are using HDS, EMC or IBM shark as it sounds like you have a fairly high end enterprise set up. The key is use vxmake not vxassist. vxmake will enable you to build the sub-disks and plexes from the ground up in ordered discrete steps, that you can verify as you go, to make a provisional mirror.
You can then attach the new provisional mirror plex which has the exact config to the original volume. You can then divorce the primary and secondary original plexes - maybe keep the secondary as a temporary backup. Destroy the original plex to free your storage, Then re-create it at the larger size you require, once again using vxmake. If you are feeling lucky you can use vxassist, but i would not advise it
When the new original plex has synced up you can divorce the provisional mirror and destroy it to reclaim the storage. Finally wait say 24 hrs then destroy the original secondary mirror and re-create at the extended size and then reattach it.
The critical issue is you need enough temporary storage to build the provisional mirror and i need to see "vxprint -g data_dg -qht" [ assuming your disk group name is data_dg ] of your set up
and "vxdisk -o alldgs list" and i can step you through the vxmake commands or Symantec support can do this. If you ring pm US East Coast time it will switch to Sydney and most of the chaps there are long term and very experienced. If you have no contract then email me the outputs
and your contact details and i will see if i can step you through them.
-gregoire
