Re: ZFS, XFS, and EXT4 compared

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

Jeffrey W. Baker wrote:
> On Thu, 2007-08-30 at 13:57 -0500, Eric Sandeen wrote:

>> barrier seems to hurt badly on xfs, too.  Note: barrier is off by
>> default on ext[34], so if you want apples to apples there, you need to
>> change one or the other filesystem's mount options.  If your write cache
>> is safe (battery backed?) you may as well turn barriers off.  I'm not
>> sure offhand who will react more poorly to an evaporating write cache
>> (with no barriers), ext4 or xfs...
> 
> I didn't compare the safety of the three filesystems, 

Understood

> but I did have
> disk caches disabled 

Oh, so for the SW raid tests the individual disks had no write cache?f

> and only battery-backed caches enabled.  Do you
> need barriers without volatile caches?

As far as I understand it, then nope, you don't need it, and you're
hurting performance with it.

-Eric