[ovirt-users] best way to remove SAN lun

[Andrea Ghelardi]

Hello Gianluca,
I have ISCSI SAN here and not FC but process should be very similar.
Correct operation is
Storage maintenance -> detach -> remove

Once you have removed the storage, Ovirt will release the sanlock.
Note that your server will still “see” the device and multipath will still list it as active.

You can now unmap LUN using your SAN manager.
If your multipath is correctly configured, device will “fail” but nothing else (multipath and server won’t hang).
You will be able to perform basic list operations via server shell without experiencing freeze or locks.*
Ovirt will continue to scan new devices so you won’t be able to manually remove them until you unmap devices from SAN manager.

If you need to remove devices manually, it is advised to follow this guide.
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/removing_devices.html

* If you do face command freeze etc, re-enable LUN mappings and check your multipath.conf

Cheers
AG

From: users-bounces at ovirt.org [mailto:users-bounces at ovirt.org] On Behalf Of Gianluca Cecchi
Sent: Tuesday, February 21, 2017 4:19 PM
To: users <users at ovirt.org>
Subject: [ovirt-users] best way to remove SAN lun

Hello,
currently I have a cluster of 3 hosts where each one has FC SAN connectivity to 4 LUNs: 3 are already configured as storage domains (1TB, 2TB, 4TB), one is free, not allocated.
See here for screenshot:
https://drive.google.com/file/d/0BwoPbcrMv8mvRVZZMTlNcTQ5MGs/view?usp=sharing

At the moment the command "multipath -l" run on hosts shows all the 4 LUNs.

Now I want to do 2 things at storage array level:

- remove the 2TB storage domain LUN
- remove the 20Gb LUN not yet allocated

What is the correct workflow, supposing I have already emptied the 2TB from VM disks ad such?
Select 2Tb SD, then Datacenter subtab, then "maintenance", detach" and at the end "remove"?

I think I continue to see 4 LUNs at this point, correct?

Now I proceed with removal of lun at storage array level?

Should I select an SD line and then "Scan disks" to see refresh the SAN and see in multipath only 2 of them at the end?
Or any manual command at host level before removal from array?

Thanks in advance

Gianluca
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