On Thu, 06 Nov 2008 17:59:32 +0000, jacqui.caren@??? said:
> We are having fum with a RAID controller
> which has started to hang on a dead drive and is not reuilding the array
> with/from the hot spare.
>
> The box is running gentoo.
Jacqui, do you know if this is a real hardware RAID controller, or does it
need some help from the OS? Many of the low-end RAID controllers are
not true hardware RAID controllers and need help from the OS driver (see
"Hardware based" and "Firmware/driver based" at
http://en.wikipedia.org/wiki/RAID#Hardware-based)
If it is a true hardware based RAID controller, the OS makes no difference
- the BIOS and OS see only the arrays of drives. Having said that, my
personal opinion is that Gentoo certainly has its place, but a typical
production server isn't it. If the array won't rebuild online, you should
be able to manipulate it from the BIOS (for example, the Dell PERC boards
have a comprehensive management facility, albeit with a tortuous UI).
If the controller is not a true hardware controller, consider getting rid
of it. There are many reasons, including the fact that most of them don't
offer very good performance and also use a proprietary (ie, secret)
on-disk format. You don't say whether you're using RAID-1 or RAID-5 (or
indeed any of the others), but if you're using RAID-1 without a dedicated
hardware RAID controller, do it in the Linux kernel. Easy to set up,
almost undetectable overhead, and if it all goes wrong you can take either
disk out, put it in another system, and read the data. RAID-5 is
computationally expensive, and as it relies on at least three drives as
opposed to RAID-1's two, it has a shorted MTBF. If you really want RAID-5,
use a proper, dedicated (read: £££) hardware controller.
I'm not sure that any of that has helped you, but maybe the first step is
to let us know if it is a dedicated h/w RAID controller.
Keith
--
Keith Edmunds
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