[OpenIndiana-discuss] Zfs stability

James Carlson carlsonj at workingcode.com
Fri Oct 12 23:44:56 UTC 2012

On 10/12/12 16:45, Robbie Crash wrote:
> Also, the reason there's so much talk about broken ZFS is because nobody
> complains when their pools aren't broken.
>> On Fri, Oct 12, 2012 at 3:55 PM, Roel_D <openindiana at out-side.nl> wrote:
>>> How come i see so much ZFS trouble?

I suspect there's more to it than that.  ZFS, unlike most file systems,
has a built-in checksum feature that checks block integrity.  If you
have problems on the drive, in the controller, in the DMA mechanism, or
in memory itself, you're liable to trip over ZFS checksum errors, which
ZFS will then try hard to repair from a mirror or RAID-Z reconstruction.

Because most other file systems don't have this capability, they just
don't notice.  Unless the drive itself flags the data as bad with an
uncorrectable low-level read error, the OS happily believes almost any
garbage it happens to read from the disk.

Thus, I believe that at least some of the people complaining about ZFS
stability problems here are actually getting a wonderful
canary-in-a-coal-mine warning out of ZFS about the reliability of the
hardware they own.  Whether those folks take that warning to heart or
simply wish it away by changing OSes, well, I guess that's up to them.

James Carlson         42.703N 71.076W         <carlsonj at workingcode.com>

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