OT: Hardware Raid 1 on linux

[Lennart Sorensen]

On Fri, Feb 06, 2004 at 05:40:17PM +0800, JM wrote:
> how does a system on raid 1 act when one of its drive fails? Will it still 
> function properly? How would I know if one of my drive fails? (without 
> physically looking at it)... would linux inform me? i have a box which is not 
> a hot swap capable.. if one disk fails i have to bring the system down and 
> replace it with the new one.. do i have to make sure that the new disk has 
> been partitioned like the one w/c ill be replacing? or will i just make a 
> filesystem similar to the one ill be replacing...

If what you have is a hardware raid card, then the syrtem should
continue running if a drive fails.  The only exception to this that I
know of is if you are using IDE disks and have two disks sharing one
cable, in which case one drive dying can stop access to the other drive
on the same cable.  No proper raid card would allow multiple ide drives
on one cable.  SCSI deals with shared cable and dead drives just fine.

If the system does not permit hotswap, you have to shut it down to
replace the drive.  The raid card should automatically start rebuilding
the raid on powerup.  Partitions are after all an OS thing done on top
of the raid, and what the raid card stores physically on the disks
really shouldn't interest the end user much.

As for finding out, well some drivers in linux will have utilities for
monitoring the raid, others report their status in /proc somewhere, a
few seem to do nothing at all that I know of.  On some systems with
hotswap scsi raid, a light on the case will come on when there is a
fault and a light on the defective drive will come on and it might start
beeping.  There is no single method used.

Lennart Sorensen
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