classiccmp server hard drive info

From: Fred N. van Kempen <>
Date: Mon Oct 4 03:34:27 2004

On Mon, 4 Oct 2004, Rob O'Donnell wrote:

> >barracuda 7200rpm 8mb cache 160gb unit.
> Is this going to be the only drive in the machine?
Yeah, this has kept me wondering, too, even when it broke last time.

> (The only problem, as with any RAID, is when you have to swap a drive and
> need to get a new one to match - I have found even the same model of drive
> from the same manufacturer, purchased at different times can report
> different capacities!)
This is not true. Especially with decent SCSI or SATA based controllers,
one only needs to match the "surviving" drive(s) with a drive of AT LEAST
the same capacity. If you have a RAID5 set of four 4.3GB drives, and
drive #2 dies, you *can* without problems replace it with a 9.1G drive,
and the array will be back up. The new drive will only have 4.3G of
it used. This was actually a normal procedure to replace old drives
with new drives in production arrays.. just replace them one at a

Controllers that require identical drives in any RAID set are not worth
the consideration in a (semi-)critical environment, as identical
replacements are not a given.

In Jay's case, I'd recomment implementing a SATA-based RAID1 set
with two SATA 160G drives- possibly with a third one as offline
or online (if the controller supports it) spare.

Received on Mon Oct 04 2004 - 03:34:27 BST

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