How to copy a specific zvol from a readonly=on pool, to a new pool

Garfje

Cadet
Joined
Jul 25, 2019
Messages
5
Hi,
I have a pool which I can only mount readonly (panics if I try to mount it rw). No snapshots on a ro pool, so can't zfs send/receive - how do I copy a specific zvol from the ro pool to another waiting, hungry rw pool?

Thanks,
--Rob.
 

Heracles

Wizard
Joined
Feb 2, 2018
Messages
1,401
Hi Rob,

The symptom you describe here is pretty strange... Is that pool loaded to 100% ? Any other clue about that panic ? Encryption was On ? Dedup was On ? Can you do some testing on the RAM to be sure it is not that one that turned bad?

What you can try is to install FreeNAS on a new USB drive, reboot your server on that drive and try to import that problematic pool from that new FreeNAS. If it does mount, do the snapshot you need for using ZFS send / receive.

Good luck,
 

Garfje

Cadet
Joined
Jul 25, 2019
Messages
5
Heracles,

It's as if you came on this journey with me :smile:. It was a 9.10-U3 installation and zfs pool which got nuked by the power outage. The pool was encrypted, and I have the GELI key to decrypt the drives to allow the "new" install of 11.2 to look at the drives and attempt the import. Neither the old 9.10 (which I have consigned to history now) nor the new 11.2 installation is able to import the pool rw. A full panic ensues about 5-7s after the import process starts.

I'm not sure how to get a good look at the panic as it scrolls pretty quickly and I guess it isn't flushing much IO to write the dump file after it happens.

The new pool "tanktoy" works just fine, and indicates the fresh 11.2 install is ticket boom. I plan to copy the VMFS zvol to that when I work out how!

The old pool "tank", is feature level 5000, and I could upgrade it but I'm nervous about doing *anything* to it prior to pulling out my 8TB zvol with plenty of lush VMs on it that I would rather not lose :eek:

BTW - server passes all hardware diagnostic tests, including the ECC memory. Nothing in the IML logs either of the iLO.

Open to suggestions how to proceed .... I must be tantalisingly close to getting this zvol out of this pool? :p

Thx
 

Heracles

Wizard
Joined
Feb 2, 2018
Messages
1,401
Hi again,

Thanks for the details. ZFS encryption often turns to a self-inflicted ransomware... Considering how little benefit it is for such a large risk, I discourage it openly.

You will understand that I do not use it at all. Neither did I used FreeNAS 9.x. As such, I will let other community members help you on that one.

You can read a little more about my view on encryption here

Good luck,
 
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