[Gllug] RAID Partitions

[Huw Lynes]

On Fri, 7 May 2004 13:30:34 +0100
Amias Channer <gllug at amias.org.uk> wrote:

> Hello all ,
> 
> I am advising on the build of a new server at the moment and was wondering
> if i could check some assumptions against you collective experiences.
> 
> The client wants to have RAID in is interested in a LSI MegaRAID Ultra320 .

We have three of these. In their previous incarnation as AMI MegaRAID.

> Would i be right in thinking that if one of the drives from a mirror is
> pulled it won't be properly readable by anything else but the same type of
> controller due to a proprietary format ?

Yes, I believe the RAID controller writes volume headers into the top of the
disk. A spare RAID controller is a necessity.

> 
> If another machine had a Ultra320 card could it backup and restore with dd ?

If you mean "can I use dd to take a copy of the disk that can then be plugged
back into the RAID controller" then theoretically yes. It would be certainly
be worth a try. If you want to rescue the filesystem then you will have to
work out where the filesystem headers start and run the dd from there. Again
theoretically possible but I've never tried it. Much better to have a spare
RAID chasis to plug the disks into.

> Also are 15k rpm discs really worth twice the cost or 10K ?

That all depends on what you are doing and where your bottleneck is. 

-- 
| Huw Lynes               | The Moving Picture Company  |
| System Administrator    | 127 Wardour Street          |
|.........................| London, W1F 0NL             | 


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