On 1 Jul 2007, at 16:05, Michael Watterson wrote:
> HW raid works with multiple boot multiple OS
> HW raid better performance, but only if it really is HW raid with
> it's OWN cpu and typically using some sort of SCSI. But SCSI
> expensive for disks.
> Any PATA or SATA ide Raid I've seen seems to be really SW based.
All RAID is software - it's just a question of where the software
runs (though of course this truism is made a lie of slightly by RAID
controllers which have hardware acceleration for common RAID
calculations, but you could still call what does thsoe calculations
software.
However, 'hardware' RAID is not limited to SCSI - there are numerous
such cards for IDE drives (3Ware and LSI do good kit) and now for
SATA too. A reasonable rule of thumb is that if the price of the card
is not in triple figures, it's not real hard RAID (where real
hardware RAID == does not use host CPU but instead has its own, with
or without accelerators)
> Big advantage of HW RAID5 over SW RAID 5 is you can boot from it.
And the big disadvantage, as Frank has identified, esp. for the small
scale user, is that you need to keep a spare card of the same model
handy in case of failure.
Niall
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