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Re: hard- or software-raid?

On Fri, 24 Jan 2003 00:16, Tinus Nijmeijers wrote:
> The system will boot of a scsi HD, I have a backup boot disk available.

Why not use RAID-1 for the boot device?

> Disks (couple of 120G IDE or something) will be in 1+0, raid5 or raid6
> (does software raid do raid6?)

What is RAID-6?  RAID-6 isn't one of the standard RAID levels (which go up to 
5).  It's sometimes used as a slang term for RAID-1+0 or RAID-0+1 (both of 
which are known by the slang term RAID-10).  Software RAID should do RAID-10, 
but I've never tested it.

> Is there any reason to use hardware-raid over software-raid in this
> case?

If you have hot-swap hardware then software RAID does everything that hardware 
RAID does for RAID-0, 1, and 10.  Hardware RAID allows easier hot-swapping in 
some situations (just physically replugging disks with no software 
adjustments) but hugely more painful hot-swapping in other situations (reboot 
and run BIOS utilities).

Good hardware RAID has a battery backed write-back cache for RAID-5 to give 
good performance, you probably won't be happy with RAID-5 performance without 
such a write-back cache.

Software RAID is good for price and for when you only want two disks in a 
RAID-1.  If you need great performance from RAID-5 and have the money for it 
then hardware RAID is the go.  Also if you need more than 4 disks it becomes 
more difficult to manage with software RAID.

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