Re: Software RAID 5 or something else?

[Alan Cox <alan lxorguk ukuu org uk>]

> 1)  Bite the bullet and get the hardware RAID controller.  Will this give
> me the performance I want?

That depends on the rest of the system - you get to play "move the
bottleneck". It will then depend on your PCI-X controller, your memory
bandwidth and if you have the CPU 8). The 3ware is at least a real
hardware driven RAID, most ATA 'RAID' is BIOS/driver RAID so just
software RAID with a disguise kit.

> 2)  Go with a software RAID 5.  Will I lose performance with this
> configuration?  If I use this but only get modest performance gains, that
> would be acceptable.

RAID 5 in software means XOR in software so has a cost, RAID 1 is much
cheaper in software if you can take the capacity hit. RAID5 also works
best with a battery backed cache which you don't get in software.

You may also find that multiple cheap PCI-X AHCI cards outperform several
drives on one card.

Alan