Need help importing old pool

[antnas]

Hi,

I'm trying to take a mirrored pair of drives from an old freenas machine and use them in a new machine. I've installed freenas to a new USB, installed the two drives, booted the machine and tried "zpool import" but I get the following:

Code:

[root@freenas-old] /tmp# zpool import
   pool: Data_Store
     id: 5668204191946265392
  state: UNAVAIL
status: The pool was last accessed by another system.
action: The pool cannot be imported due to damaged devices or data.
   see: http://illumos.org/msg/ZFS-8000-EY
config:

        Data_Store                                      UNAVAIL  missing device
          mirror-0                                      ONLINE
            gptid/c3e912a1-0c3a-11e6-92f4-0024e844076b  ONLINE
            gptid/c565ca61-0c3a-11e6-92f4-0024e844076b  ONLINE

I don't know what the "missing device" could be.

Unfortunately the old machine is now running a new raid array and I can't really take it offline. How do I get this old array back up and running in the new setting?

Thanks!

 

[Sakuru]

Did the old pool have a SLOG or L2ARC?

 

[antnas]

Did the old pool have a SLOG or L2ARC?

No. Just a vanilla mirrored pair of drives, as far as I can recall.

 

[antnas]

For what it's worth, here's the output of "zdb -e Data_Store":

Code:

[root@freenas-old] ~# zdb -e Data_Store

Configuration for import:
        vdev_children: 2
        version: 5000
        pool_guid: 5668204191946265392
        name: 'Data_Store'
        state: 0
        hostid: 837380115
        hostname: ''
        vdev_tree:
            type: 'root'
            id: 0
            guid: 5668204191946265392
            children[0]:
                type: 'mirror'
                id: 0
                guid: 15581886660630646275
                metaslab_array: 35
                metaslab_shift: 34
                ashift: 12
                asize: 1998246641664
                is_log: 0
                create_txg: 4
                children[0]:
                    type: 'disk'
                    id: 0
                    guid: 17427694859737410091
                    whole_disk: 1
                    create_txg: 4
                    path: '/dev/gptid/c3e912a1-0c3a-11e6-92f4-0024e844076b'
                children[1]:
                    type: 'disk'
                    id: 1
                    guid: 13504215445269714232
                    whole_disk: 1
                    create_txg: 4
                    path: '/dev/gptid/c565ca61-0c3a-11e6-92f4-0024e844076b'
            children[1]:
                type: 'missing'
                id: 1
                guid: 0
zdb: can't open 'Data_Store': No such file or directory

 

[Robert Trevellyan]

It appears there was a third drive striped with the mirror. Without that device connected, you won't be able to import the pool.

 

[antnas]

That's very strange. There was a second pair of drives in the machine at one point, but they weren't part of the Data_Store volume. Is there any way to get more info about the "missing" device? Or tell FreeNAS to ignore it on import?

 

[Robert Trevellyan]

Here's the (simplified) structure of the pool, according to the zdb command you ran:

Code:

name: 'Data_Store'
        vdev_tree:
            children[0]:
                type: 'mirror'
            children[1]:
                type: 'missing'

1. According to what I've gathered in these forums, ZFS commands can't tell you anything about a vdev for which no device is present.
2. The only devices that can be ignored for the purpose of importing a pool are L2ARC and SLOG.
3. If any vdev in a pool fails or is absent, the pool is lost (because pool data is striped across all member vdevs).

So, unless you can find and install the missing device(s), the pool can't be imported.

 

[antnas]

Thanks Robert. That's a shame. Is there a way to fake the missing vdev? Maybe add two drives to the system to pretend to be them?

 

[SweetAndLow]

There was another vdev in this pool that is now missing. So those drives you said that where in the system that you though where not part of the pool where actually part of the pool so you need them back.

EDIT: No you need the original drives back with the original data to make the pool mountable.

 

[antnas]

OK, well that sounds like game over. The original drives are in a new pool on another FreeNAS machine.

 

[Robert Trevellyan]

Is there a way to fake the missing vdev?

Even if you could, you wouldn't get the data back, because...

pool data is striped across all member vdevs

 

[antnas]

Thanks. I've read your presentation now, and have a better handle on things. Thanks for taking the time to share what you know.

 

[Robert Trevellyan]

I've read your presentation now, and have a better handle on things. Thanks for taking the time to share what you know.

I can't take credit for the presentation, but you're welcome.