Performing storage migrations using VXVM
This procedure was used for migrating data from a HDS USP to USP-V disk array. One of the requirements was to convert thick volumes to thin provisioned volumes. This procedure uses a VXVM function utility to achieve this but obviously only works for VXVM volumes.
The procedure works by creating a plex from LUN on the new array, attaching it to the volume to be migrated, creating a mirror, then detaching the original plex. Using the inbuilt usefssmartmove function ensures that thick volumes are converted to thin provisioned volumes.
- Create file /etc/default/vxsf with the following entry, usefssmartmove=all
- Create a LUN on the new array and initialise the new LUN under VXVM
- Add to the appropriate diskgroup
- Create a subdisk from the LUN: vxmake -g dg sd subdisk-name diskname,0,102236160 (where 102236160 is the size in blocks and should be the same size as the subdisk you want to copy)
- Create a plex from the subdisk: vxmake -g dg plex plex-name sd=subdisk-name
- Attach the plex to the volume to be copied: vxplex -g dg att volname plex-name
- Once synchronised detach the plex: vxplex -g dg dis original-plex
- Plex can removed later using: vxedit -g dg -r rm /original-plex