My Unraid 7.0 upgrade went very smoothly!  My thanks to the Unaid team and beta testers.

 

After upgrading my 5 x 18TB RAIDZ2 to the Unraid 7 standard, I added a two-slot L2ARC subpool with a matching pair of SSDs.

 

I got the warning that the drives would be formatted, which is what I wanted.  Everything seemed to work fine.

 

But now I see that the drives are showing up with partition formats of "MBR: 1MiB-aligned" rather than GPT.

 

I decided to remove the L2ARC subpool through the GUI and try again.  But I can't find a way to remove it.  Nor can I reduce the slot count below 2.  If I remove one or both drives, then I can't start my array because of the missing drives.

 

Where do I go from here?  Any insight would be greatly appreciated.

1 hour ago, Miss_Sissy said:

But now I see that the drives are showing up with partition formats of "MBR: 1MiB-aligned" rather than GPT.

What capacity are the drives? Anything up to 2TB will be formatted MBR by Unraid

3 hours ago, JorgeB said:

What capacity are the drives? Anything up to 2TB will be formatted MBR by Unraid

That explains the MBR part; they are 240GB SSDs.

 

It was oh-dark-thirty when I rushed into my L2ARC experimentation, but I assumed that I could later remove one or both L2ARC cache drives based on my 'research'.  Is that not possible using the GUI; is it something that I have to do with zpool console commands?  I think that I know how to do that, but I'd sure like something official before I start mucking around like that.

 

Thanks!

 

 

The GUI does not currently support removing any type of subpools, but they can be removed manually, when zfs allows that, i.e., special and dedup vdevs cannot be removed if the main vdev is raidz.

 

After manually removing it, you just need to reimport the pool:

 

on main click on that pool and then "remove pool"
back on main, create a new pool with the same name and the correct number of slots
assign the pool device(s), leave the filesystem set to auto
start the array to import the pool

Thanks for your help JorgeB!

11 minutes ago, JorgeB said:

The GUI does not currently support removing any type of subpools...

That is a shame.  If customers can create and add drives to L2ARC subpools from the Unraid GUI, one would expect that the GUI would also supply the complementary features to remove cache drives and/or the entire L2ARC cache.

 

I guess I'll turn to the zpool help:

 

For further help on a command or topic, run: zpool help [<topic>]
root@Unraid-NAS:~# zpool help
couldn't run man program: No such file or directoryroot@Unraid-NAS:~# 

 

Just super...  I did not remove the man command, so where is it?  I just did a straight upgrade from the latest six-dot version of Unraid.  I didn't erase 'man' or muck about with the path.

 

Quote

After manually removing it, you just need to reimport the pool:

 

I want to make sure that I have this exactly right before I start typing and clicking.  This is my ZFS pool named simply 'zfspool'.

 

root@Unraid-NAS:~# zpool status
  pool: zfspool
 state: ONLINE
  scan: scrub repaired 0B in 08:36:39 with 0 errors on Sun Jan  5 11:36:40 2025
config:

        NAME         STATE     READ WRITE CKSUM
        zfspool      ONLINE       0     0     0
          raidz2-0   ONLINE       0     0     0
            sdb1     ONLINE       0     0     0
            sdc1     ONLINE       0     0     0
            sdd1     ONLINE       0     0     0
            sde1     ONLINE       0     0     0
            sdf1     ONLINE       0     0     0
        cache
          nvme0n1p1  ONLINE       0     0     0
          nvme1n1p1  ONLINE       0     0     0

errors: No known data errors

 

Would this be the proper command to remove the cache drives?

 

With the array running (according to what the Unraid GUI says):

 

# zpool remove zfspool nvme0n1p1 nvme1n1p1

 

Then, from the GUI, I would stop the array, click on the pool name (zfspool) and remove (not erase!) it.  From there, I would re-import the five-drive RAIDZ2 pool by creating the pool with the same of "zfspool", assigning five slots to it, putting the same drives into the same slots, and then importing?

 

If this or some variant is the go-to method, I hope that Lime Technology creates some sort of step-by-step video or knowledgebase article. 

 

Thanks again.

16 hours ago, Miss_Sissy said:

That is a shame.  If customers can create and add drives to L2ARC subpools from the Unraid GUI, one would expect that the GUI would also supply the complementary features to remove cache drives and/or the entire L2ARC cache.

I agree, but they cannot do everything at the same time, I would expect that functionality to be added in the near future.

 

16 hours ago, Miss_Sissy said:

putting the same drives into the same slots, and then importing?

The procedure is correct as described, when reassigning, you can do it in any order, it will sort them during import.

 

17 hours ago, JorgeB said:

The procedure is correct as described, when reassigning, you can do it in any order, it will sort them during import.

Thank you!  With the potential downtime and data recovery time should I do something wrong, I wanted to be absolutely certain about the process before starting.

On 1/12/2025 at 9:44 PM, Miss_Sissy said:

Thank you!  With the potential downtime and data recovery time should I do something wrong, I wanted to be absolutely certain about the process before starting.

did it work for you?

I am at the same position now