[sclug] hot drives

[Dickon Hood]

On Tue, Jun 20, 2006 at 00:12:41 +0200, Pieter Claassen wrote:
: On Monday 19 June 2006 01:40, Dickon Hood wrote:

: > : I have two 120GB Maxtors in a soft raid config (actually they are
: > : plugged into a cheap PCI PATA raid card but after config, the linux
: > : kernel still sees them as two disks so I just went with soft raid).

: > It works.

: Simple question. Why when I configure the SATA raid card and add the two 
: drives to an array do I still get presented with a two scsi devices in the 
: kernel? What does this mean? I was under the impression that a successful hw 
: config would present only a single raid device to the kernel.

I can imagine scenarios with either one or three SCSI devices being
presented: one HW RAID device only, or one HW RAID device, plus one each
of the raw devices (so you can query them for status (temperature, that
sort of thing)).

: Even more intriguing, what happens if I configure HW raid as well as SW raid 
: and then have a drive fail?

I should imagine you're not seeing the HW RAID device at all, so the
chances are, the software RAID will sort it.  You might want to check that
you've got the right RAID driver compiled in / module loaded.

I've played with hardware RAID under Linux once.  I hate it.  Use
software.  If you need the performance, buy a faster (or second...) CPU...

This particular thing had a standardish chipset which could be used in
JBOD mode (which I did), and some RAID thing.  I gave up fighting with the
module (binary blob) eventually.

I reserve all rights to be wrong.

-- 
Dickon Hood

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