ZFS RaidZ2 with 24 drives?

[Solon Lutz]

> I deployed using the two configurations you see above. Both machines  
> have a pair of Areca 1231ML RAID controllers with super-sized BBWC  
> (battery backed write cache). On back01, each controller presents a 12- 
> disk RAID-5 array and ZFS concatenates them into the zpool you see  
> above. On back02, the RAID controller is configured in JBOD mode and  
> disks are pooled as shown.

Why concatenate them into one pool and give up the redundancy?

I have the same setup: Areca 24-port RAID6 (24x 500gb)

        NAME        STATE     READ WRITE CKSUM
        temp        ONLINE       0     0    24
          da0       ONLINE       0     0    48
 
And it very nearly killed itself after 28 months of flawless duty...
All went fine until 4 drives disconnected themselves from the Areca due
to faulty SATA-cables. This crashed the Areca in such a way, that I had
to disconnect the battery module from the controller in order to get it
initialized during boot-up.

Cache gone - ZFS unable to mount 10TB pool - scrub failed - I/O errors

This was three months ago and if I hadn't found an extremly skilled person
who was able to manually find and distinguish between good and corrupted
meta-data sets, replicate them in their proper spots and zero out corrupt
transaction ids - I would have lost 10TB of data. (No backups - to expensive)

Why do you use JBOD? You can configure a passthrough for all drives,
explicitly degrading the Areca to a dumb sata controller...


Best regards,

Solon Lutz


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