Accepted Solution

Cutting over iSCSI LUNs between filers

I need to cutover from one FAS to another, a task I have accomplished many times before using SnapMirror to transfer the data.  Using OnTap 7.3.7

Previously I have only had to cutover CIFS and NFS, however on this occasion I also have two iSCSI LUNs.

How does the new FAS recognise the LUNs which were created on the original FAS? I assume I will also need to configure initiator groups.

I can't see any config files in my etc directory in the root volume which relate to iscsi.

Can someone advise on the right way to migrate iSCSI LUNs between filers?

Re: Cutting over iSCSI LUNs between filers

I have done this before.  Snapmirror the data, and the new controller will see the luns with "lun show".  You're right, you'll need to configure the inititator groups, etc.

One caveat - luns have a serial number that I don't believe is copied with snapmirror.  Some applications (Exchange comes to mind) are picky about this serial number; they won't let you use data on a different lun serial, even though it's the same drive letter.  List the existing lun's serial with "lun serial <lun_path>", and set the new lun's serial with "lun serial <lun_path> <serial>".


Re: Cutting over iSCSI LUNs between filers

  1. Unmount iSCSI LUNs on hosts
  2. Shut down iSCSI on filer
    o iscsi stop;iscsi status
  3. Perform snapmirror update
  4. Perform snapmirror break
  5. Make a copy of iscsi nodename from the orignal source filer
  6. Modify nodename <dfiler> iscsi nodename
    o iscsi nodename [<new_nodename>]
    o iSCSI target nodename:
  7. Create igroups on filer and verify initiators are logged in
    o igroup create -i -t windows <igroup> <iqn>
  8. igroup show –v
  9. Note the orignal LUNs Serial number
  10. Change LUNs to original serial number
    o priv set advanced;lun offline <LUN>
  11. lun serial <LUN> Hnd5CZjW3OrO
  12. lun online <LUN>
  13. Map LUNs with iSCSI initiator groups and verify
    o lun map <LUN> <igroup> <LUN_id>
  14. lun show -v <LUN>
  15. Check to see if hosts can mount LUNs.  If not, reboot and re-verify
    o Restart iSCSI service on hosts if necessary
    o Remount iSCSI LUNs on hosts
    o iscsi session show (used to verify iSCSI session)

I found the above steps to be a cleaner way to migrate LUNs to new filer.

Re: Cutting over iSCSI LUNs between filers

Yes, you will need to manually create igroups and mapping on destination filer - they are not replicated. Also LUN serial numbers will change - this may be problem depending on host OS (e.g. VMware will not mount them by default).