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Date:      Sat, 26 Jun 2004 06:01:10 +0200
From:      "Daniel Eriksson" <daniel_k_eriksson@telia.com>
To:        "'Benjamin P. Keating'" <bkeating@gmail.com>, <freebsd-questions@freebsd.org>
Subject:   RE: fsck'ing a Vinum RAID5 volume (and a stale drive)
Message-ID:  <!~!UENERkVCMDkAAQACAAAAAAAAAAAAAAAAABgAAAAAAAAA0VcX9IoJqUaXPS8MjT1PdsKAAAAQAAAAqqgjgXD/1kSNFsy0Utn3AwEAAAAA@telia.com>
In-Reply-To: <1d54d54404062518474bbb3494@mail.gmail.com>

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Benjamin P. Keating wrote:

> Is
> this approach correct? does this do anything productive or just forces
> the state label to change and do nothing to the drives? I don't feel
> confident that it did anything and Im having a VERY hard time finding
> documentation on this.

Let me give you an example of a valid setstate use case:

One of my servers has a LOT of discs. For some reason I suffer from
interrupt storms during device probing (started after I added a second
Highpoint RocketRAID 454 to the machine). These storms sometime prevent =
the
ata code from detecting all the discs. If this happens to be a disc that =
is
part of a RAID-0 array, then when vinum starts up it detects that one of =
the
discs have disappeared and (correctly) marks the array as crashed. There =
is
no "proper" way to recover from a crashed RAID-0 array - your data is
normally lost forever. However, in this specific case I _know_ that =
nothing
has been written to the discs, so once I get the missing disc back =
online I
can use setstate to change the array status from crashed to up, =
confident
that no data has actually been lost.

There are a few other use cases for setstate, but they are all (?) =
outside
of the normal procedures for using and maintaining RAID arrays.

/Daniel Eriksson




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