Recovering from a failure.

[Ste]

I have a FreeNAS Mini that has suffered what appears to be a motherboard failure. I have a FreeNAS Min XL, with enough empty slots to move the four drives from the failed units to it. I have several questions:

1) Must I power off the XL, when installing the four drives from the failed unit?
2) How do I get the XL to recognize the additional volume?
3) The volume names in both units is called "tank". Will that be a problem when adding the drives to the XL? If so, how do I work around that?

Thank, in advance, for your guidance.

-ste

 

[Robert Trevellyan]

1. Recommended, especially because of #3.
2. Use the GUI to import it.
3. Yes, it will be a problem. The simplest approach is to detach the existing pool and disconnect the drives in preparation for working with the orphaned pool. May as well transfer the boot device too. It's also possible to import a pool with a new name using the CLI (man zpool for details).

 

[Ericloewe]

zpool import oldname newname, IIRC.

 

[Ste]

Using the GUI, I detached the existing pool in my Mini XL, powered it off, and removed the drives. I installed the drives from the failed unit and powered it on. A 'zpool list' showed only the boot device but not the 'tank' pool, so I tried 'zpool import tank' which appeared to see it, but wouldn't import it because it appeared to be in use.

That made sense to me, as that pool was never properly detached before the unit they came from died. So, I looked over the options, and elected to run 'zpool import -f -m -F -n tank', which did, indeed, import the pool. I couldn't see it in the GUI however, and a 'df' shows that it's mounted at /tank instead of /mnt/tank. I tried to detach it with 'zpool detach tank', so that I could try to re-import it as /mnt/tank, but it complained that I didn't specify a device.

I've now simply copied my data off of this pool, and I want to detach it, but I don't know how, as I don't know what to specify for a device. I also don't know how to re-import this unit's 'tank' pool, as /mnt/tank, once I swap these drives out and the originals back in.

Would someone please help me craft these command properly?

 

[Robert Trevellyan]

zpool detach tank

That should be zpool export tank. See the documentation for details.

 

[Ste]

Okay, I'll look at export. I'd note, though, that earlier in this thread, I was told to 'detach' the pool. Also, the GUI labels the button at the bottom of the screen as "Detach Volume". I used that GUI button to detach this unit's original drives. I still don't know how to bring it back as /mnt/tank and not /tank.

 

[Robert Trevellyan]

I'd note, though, that earlier in this thread, I was told to 'detach' the pool.

You were also encouraged to read the documentation. My use of the word "detach" was not in the context of a command-spec. Spoon-feeding is not what you get here. Take the information give, verify it, cross-check it, then use what you've learned.

 

[Ste]

You know, I *did* read the documentation previously. How do you think I came up with the commands I said I ran? I focused on detaching though, because that is what I'd been told to do, and that is what the GUI calls it. Who am I to presume that when I'm told 'detach', what is really meant is 'export'?

Clearly, I didn't understand what I had read in the documentation, or I wouldn't have still been asking questions. But thank you for pointing me at 'export' - I'll see if I can make some further progress now.

 

[Robert Trevellyan]

OK, well I was a bit grumpy when I posted my last reply, sorry if it was abrupt.

 

[Ste]

Okay, I'm slowly learning this. In regards to moving my mount of tank (from the failed Mini, inserted into the Mini XL) from /tank to /mnt/tank, I found that setting the mountpoint property moved it to the proper location, but the GU still couldn't see it. In any case, I was done with that set of disks, having copied off the data, so I shut it down (forgetting to export that volume first), removed the disks, and put the Mini XL's original disks back in.

I powered it up and (from the GUI) tried to import this unit's original tank volume (that had been exported earlier, via the GUI, by using the 'Detach Volume' button), but it failed to import and told me to look at 'zpool status'. I ran that, and it seems like it's still seeing the failed Mini's disks (there were four, as two mirrors, and a log device [which I always had to use -m to ignore on import, since I didn't bring the log device over], instead of the single two-disk mirror that is physically in the Mini XL now. Can you point me in the right direction? Here's the 'zpool status' output:

[root@fnmxl1 ~]# zpool status
pool: freenas-boot
state: ONLINE
scan: scrub repaired 0 in 0h0m with 0 errors on Mon Feb 6 03:45:23 2017
config:

NAME STATE READ WRITE CKSUM
freenas-boot ONLINE 0 0 0
gptid/4561e25b-439d-11e6-9d5d-d05099c09d82 ONLINE 0 0 0

errors: No known data errors

pool: tank
state: UNAVAIL
status: One or more devices could not be opened. There are insufficient
replicas for the pool to continue functioning.
action: Attach the missing device and online it using 'zpool online'.
see: http://illumos.org/msg/ZFS-8000-3C
scan: none requested
config:

NAME STATE READ WRITE CKSUM
tank UNAVAIL 0 0 0
mirror-0 UNAVAIL 0 0 0
7020093230999759237 UNAVAIL 0 0 0 was /dev/gptid/f5ed9209-4368-11e4-b7a2-d050992ed09c
6797398022085867470 UNAVAIL 0 0 0 was /dev/gptid/f67f815c-4368-11e4-b7a2-d050992ed09c
mirror-1 UNAVAIL 0 0 0
12114334558594323339 UNAVAIL 0 0 0 was /dev/gptid/6aa8c345-467b-11e4-8cd0-d050992ed09c
17660870568216302219 UNAVAIL 0 0 0 was /dev/gptid/f798a8d9-4368-11e4-b7a2-d050992ed09c
logs
6775395539198347000 UNAVAIL 0 0 0 was /dev/gptid/b30a8a74-4d2c-11e5-86cd-d050997949e9
[root@fnmxl1 ~]#

 

[Robert Trevellyan]

First, the reason the transferred pool didn't show up in the GUI is because it was imported via the CLI. This is just FYI.

Next, I suggest you disconnect the good pool before proceeding, because I haven't tested anything below.

I think the issue you're seeing with the ghost of the transferred pool could be resolved by reconnecting those drives and doing zpool export. You might even be able to zpool export or zpool destroy it without attaching the disks. There might also be a shortcut if you can locate and delete the zpool.cache file.

 

[Ste]

Thank you, Sir. I removed /boot/zfs/zpool.cache and /data/zfs/zpool.cache.saved, rebooted, and successfully imported the Mini XL's original tank volume, via the GUI.

Thanks for helping me to recover, as well as learning a few things along the way. :)

 

[Robert Trevellyan]