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Re: RAID question



Gary Dale wrote:
> To elaborate, declaring them RAID in the BIOS will make them look
> like one drive. This would prevent mdadm from operating
> entirely. You would be relying on the motherboard's firmware to
> handle the RAID, which is generally not a good idea.

One general problem with BIOS raid is that the raid formats stored
onto the disks is usually a proprietary format.  If the motherboard
dies for any reason then you will also lose the data on the disks
unless you have an identical raid controller motherboard upon which to
transfer the drives.  The disks may be raid and okay but a motherboard
loss is a single point of failure.

> Unless you have a high-end RAID controller, mdadm works best.

I would add unless you have *two* or more identical raid controllers
so that you can transfer the disks and rescue the data in the case of
a raid controller card failure then mdadm works best.  With mdadm the
disks are always visible to any other system.  With mdadm no special
hardware is needed.

Hardware raid controllers work really well in data centers with rack
after rack of identical systems.  But for SOHO (Small Office Home
Office) use needing redundancy of identical raid cards is
problematic.

Bob

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