Exchange LOG-Device

[basstscho]

Hello,

I have a Freenas 11.3-BETA1 with a Pool out of 4 4TB HDDs ("Raid 10") and 2 SSDs in a mirror as log (see attached file). Now I'd like to exchange these two ssds with new ones. What's the best way to do this?

1) Remove the LOG-Disks one by one and than expand the Pool again with the new disks? Will the mirror log-mirror be deleted automatically after the last drive was deleted?
2) Replace them one by one? The new disks a bigger than the old ones - so I think this will not work.
3) Another way?

Do I have to consider something else - f.e. no writes on the system while deleting the drives? It's my first time doing this kind of exchange and i want to be sure to not destroy something.

Thank you and best regards,
Johannes

 

[HoneyBadger]

Welcome to the forums.

Let's start with Step 0 - what are the models of the old and new SSDs? LOG devices have some specific requirements and it's good to make sure you'll get an overall upgrade as an end result.

This is a live upgrade, but your desired upgrade path will depend on if you can handle the (significantly) reduced performance if you are entirely missing the top-level SLOG device. If you can handle the performance loss (and it may be significant!) then remove the top-level log vdev, physically swap devices, and add the new log vdev as a mirror of the new devices.

If you can't accept the performance loss - remove one log device at a time, swap one device, attach it as a mirror (be careful not to create a stripe, but the UI shouldn't let you) and you'll stay operational the whole time. (Just make sure you identify which disk is the "inactive" member of the log group before you pull it out!)