Recovering from a system failure, questions.

[katana1096]

First, I would like you guys to know that I am new Freenas so my questions are basically some concerns that I have.


How do I act if there happened a system failure if :-
Let say if I have ZFS with 10 drives. If one had gone bad, will the system notify me? And I just need to change the bad drive with a new one and the system will do the rest?

The OS had gone bad due to the hard drive installed had gone bad? If I just change the hard drive then install the OS again, will the system detect the previous arranged configuration of the RAID? Or there is something that needs to be done.

Please advise me and thank you.

 

[Samuel Tai]

Let say if I have ZFS with 10 drives. If one had gone bad, will the system notify me? And I just need to change the bad drive with a new one and the system will do the rest?

It depends on the construction of your pool. An bad unassigned disk not in use won't alarm until it's added to a pool, and something goes wrong during the add. A disk already in a pool will definitely alarm. There's a specific manual procedure to replace a disk, and you have to tell the pool a replacement disk is in place before resilvering starts. See the Guide, Section 10.5.1.

The OS had gone bad due to the hard drive installed had gone bad? If I just change the hard drive then install the OS again, will the system detect the previous arranged configuration of the RAID? Or there is something that needs to be done.

If the boot pool goes bad, then to recover, you need to reinstall the OS to a new drive, and then import a saved config. Hopefully, you'll have already saved your config per the Guide, Section 7.1. The same section also shows how to upload a saved config to a replacement install. Once the config is back, the OS will know about your pools, and they'll be back as well.

It gets a bit more involved if encryption is involved. In that case, you also have to save the encryption key and recovery key, per the Guide, Section 10.2.2, beforehand, and use the recovery key to reimport your pool after restoring the config. Also, it's a good idea to reset and regenerate new encryption keys and recovery keys after restoring your pool after any disk replacements.