Spurious reboot in 8.1-RELEASE when reading from ZFS pool with > 9 disks

[Sean Thomas Caron]

Hi Lawrence,

Interesting; have you tried this for raidz2 as well?

I just created a raidz2 pool with 5 disks and then added another 5  
disk raidz2 to it, so, total of 10 disks in the pool (though this is  
ultimately a losing strategy unless the number of disks is >> 9  
because two drives are lost for parity in each sub-raid in the pool).

It (seemed) just slightly more stable than creating a single raidz2  
pool with > 9 disks but it still crashes.

I guess this does allow me to say its more an issue of number of  
devices in the pool versus capacity of the pool because with the  
parity drives taken out, the pool with two 5-disk raidz2s has less  
total capacity than a pool with a single 9-disk raidz2.

Just out of idle curiousity, I also tried it with raidz1 on my system.  
Again, I created a 5-disk pool, raidz1 this time, then added another  
5-disk raidz1 to the pool for, again, total of 10 disks.

Again, a bit of a losing strategy versus creating one great big raidz  
unless the number of disks is >> 9 because of losing a disk in each  
sub-raidz1 in the pool for parity but less so of course than raidz2.

This seemed to crash too, same behavior.

Are you using 8.1-RELEASE or STABLE or ...?

Best,

-Sean

>
> I have a 16 disk pool, if you create it with
>
> zpool create poolname raidz disk1 disk2 disk3 etc
>
> then
>
> zpool add poolname raidz disk8 disk9 disk10 etc
>
> You get the full size pool and no issues.
>
>   pool: tank
>  state: ONLINE
>  scan: scrub repaired 0 in 0h0m with 0 errors on Wed Oct 20 14:54:08 2010
> config:
>
>         NAME        STATE     READ WRITE CKSUM
>         tank        ONLINE       0     0     0
>           raidz1-0  ONLINE       0     0     0
>             da0     ONLINE       0     0     0
>             da1     ONLINE       0     0     0
>             da2     ONLINE       0     0     0
>             da3     ONLINE       0     0     0
>             da4     ONLINE       0     0     0
>             da5     ONLINE       0     0     0
>             da6     ONLINE       0     0     0
>             da7     ONLINE       0     0     0
>           raidz1-1  ONLINE       0     0     0
>             da8     ONLINE       0     0     0
>             da9     ONLINE       0     0     0
>             da10    ONLINE       0     0     0
>             da11    ONLINE       0     0     0
>             da12    ONLINE       0     0     0
>             da13    ONLINE       0     0     0
>             da14    ONLINE       0     0     0
>             da15    ONLINE       0     0     0
>
> errors: No known data errors
>