Best way to replace degraded mirrored boot device

[trinxie]

I am running FreeNas 9.3 and have two mirrored SDHC USB sticks (da0p2, and da1p2 according to GUI)
What if one of them gets degraded, How do I know which one to replace?
If I remove the wrong one I suppose I have to reinstall.
For degraded disks in my storage pool, I can identify the disk using the serial number.
I just want to be prepared

 

[dlavigne]

You could try booting with the one that you think is still working (after removing the one that you think is broken), before performing the replacement.

 

[trinxie]

OK, so I am able to test out which one that is broken. I was not sure if I actually could do that without degrading both of them.
Thanks !
(Maybe I should have posted this into another thread... hmmm)

 

[dlavigne]

Yeah, that's the nice thing about a boot mirror. The system can still boot from the good device, as long as at least one device in the mirror is still good. Depending upon the BIOS, you might have to tell the system which device to boot from until the mirror is fixed.

 

[trinxie]

That is ok as long as grub recognize it. I played around with mirrored boot during 9.3 Beta and then I got into a state where grub did not recognize my OK disk. Strange, I considered this an early beta problem and reinstalled. Maybe got me a bit worried, did not figure out what went wrong. Earlier during 8.x I had a boot failure, I reinstalled, uploaded config and all was fine. That is quite nice as well. Yes I really love the mirrored boot concept.