Re: ZFS on current vs wedges - best practice?

[Frank Kardel <kardel%netbsd.org@localhost>]

Hi Jeff !

Yes, you can use wedge names.

you can configure thm like "zpool create tank raidz2 wedges/wedgename-a 
wedges/wedgename-b wedges/wedgename-c wedges/wedgename-d wedges/wedgename-e"

For wedges to work you need to start devpubd (/etc/rc.conf: devpubd=YES) 
before ZFS. Currently devpub start too late with its dependencies.

To start devpubd earlier you can use following dependencies in 
/etc/rc.d/devpubd

# PROVIDE: devpubd
# REQUIRE: root
# BEFORE:  DISKS

to recover (not tested) you may try:

start devpubd

zpool export tank # you may try without this first

zpool import -d /dev/wedges # list found pools

zpool import -d /dev/wedges -a # imports all found pools

Use the hints at your own risk. I learned those when we briefly 
(9.99.85-9.99.86) broke zfs vdev access via symlinks. be sure to use a 
recent (>2021-07-18) -current kernel in case you are running -current.

Frank

On 07/19/21 19:52, Jeff Rizzo wrote:
> I had forgotten about this little detail, and am not sure about the 
> best way to deal with it.
>
>
> I have four disks partitioned with GPT (so I can create a raidframe 
> raid1 on part of the disk, and use the rest for ZFS), and I made the 
> mistake (?) of using wedge names to create the zpool.  So, after a 
> reboot (but not the first time! only happened after n reboots), the 
> wedges reordered themselves, and now my zpool looks like this:
>
>
>     NAME                      STATE     READ WRITE CKSUM
>     tank                      UNAVAIL      0     0     0
>       raidz2-0                UNAVAIL      0     0     0
>         3140223856450238961   UNAVAIL      0     0     0  was /dev/dk4
>         1770477436286968258   FAULTED      0     0     0  was /dev/dk5
>         11594062134542531370  UNAVAIL      0     0     0  was /dev/dk6
>         dk7                   ONLINE       0     0     0
>
>
> I _ think_ I can figure out how to recover my data without recreating 
> the entire pool.  (I hope - suggestions there welcome as well!  Once I 
> recover this time, I'm going to have to replace the vdevs one at a 
> time anyway because I just realized they wedges are misaligned to the 
> underlying disk block size.  Sigh.)
>
>
> However, I'm not sure the best way (is there a way?) to keep this from 
> happening again.  Can I use wedge names? (Will those persist across 
> boots?)  Other than this minor detail, I've been quite happy with ZFS 
> in 9 and -current.