"Stephen C. Tweedie" wrote:
> Hi,
>
> On Fri, 07 Jan 2000 13:26:21 +0100, Benno Senoner <[EMAIL PROTECTED]>
> said:
>
> > what happens when I run RAID5+ jornaled FS and the box is just writing
> > data to the disk and then a power outage occurs ?
>
> > Will this lead to a corrupted filesystem or will only the data which
> > was just written, be lost ?
>
> It's more complex than that. Right now, without any other changes, the
> main danger is that the raid code can sometimes lead to the filesystem's
> updates being sent to disk in the wrong order, so that on reboot, the
> journaling corrupts things unpredictably and silently.
> There is a second effect, which is that if the journaling code tries to
> prevent a buffer being written early by keeping its dirty bit clear,
> then raid can miscalculate parity by assuming that the buffer matches
> what is on disk, and that can actually cause damage to other data than
> the data being written if a disk dies and we have to start using parity
> for that stripe.
do you know if using soft RAID5 + regular etx2 causes the same sort of
damages,
or if the corruption chances are lower when using a non journaled FS ?
is the potential corruption caused by the RAID layer or by the FS layer ?
( does need the FS code or the RAID code to be fixed ?)
if it's caused by the FS layer, how does behave XFS (not here yet ;-) ) or
ReiserFS in this case ?
cheers,
Benno.
>
>
> Both are fixable, but for now, be careful...
>
> --Stephen
