choosing a file system

[Robert Banz]

On Jan 8, 2009, at 4:46 PM, Bron Gondwana wrote:

> On Thu, Jan 08, 2009 at 08:01:04AM -0800, Vincent Fox wrote:
>> (Summary of filesystem discussion)
>>
>> You left out ZFS.
>>
>> Sometimes Linux admins remind me of Windows admins.
>>
>> I have adminned a half-dozen UNIX variants professionally but
>> keep running into admins who only do ONE and for whom every
>> problem is solved with "how can I do this with one OS only?"
>
> We run one zfs machine.  I've seen it report issues on a scrub
> only to not have them on the second scrub.  While it looks shiny
> and great, it's also relatively new.

You'd be surprised how unreliable disks and the transport between the  
disk and host can be. This isn't a ZFS problem, but a statistical  
certainty as we're pushing a large amount of bits down the wire.

You can, with a large enough corpus, have on-disk data corruption, or  
data corruption that appeared en-flight to the disk, or in the  
controller, that your standard disk CRCs can't correct for. As we keep  
pushing the limits, data integrity checking at the filesystem layer --  
before the information is presented for your application to consume --  
has basically become a requirement.

BTW, the reason that the first scrub saw the error, and the second  
scrub didn't, is that the first scrub fixed it -- that's the job of a  
ZFS scrub.

-rob