[...]
> We will infact put each IDE drive on its own channel, but our testing
> reveals that RAID5 doesn't know when to stop (or maybe how to
> stop gracefully).... If two drives go out I would hope that the array
> just stop, not corrupt the data, or continue operating.
>
> This same secenerio could happen with SCSI if there were several
> drives on each of two controllers and a controller or cable went down.
> I think you'd agree data corruption is not acceptable under these
> conditions.
>
> Comments anyone?
I don't know if my experience reflects the general case, but just this
morning I arrived at work to discover one of the two SCSI controllers
supporting a RAID5 MD array was dead. After swapping in a new controller,
things resumed working as usual.
When I discovered the problem, the system was still successfully serving
NFS from a RAID5 filesystem connected to a third controller, but was
otherwise unusable - the console was blank and sshd was not responding.
I pressed the reset button, diagnosed the problem with the Symbios ROM
utilities and in single-user mode, swapped out the card, rebooted into
multi-user mode, and the array came up OK. As it resynced itself
(necessary because of the ungraceful shutdown - even the array without
hardware failure had to resync), I fscked the filesystem clean without any
trouble.
- C
--
Chance Reschke
University of Washington Astronomy
