RAID1 is DEGRADED, but which disk is faulty?

[jesse reynolds]

At 9:41 +0000 5/9/2003, Mark wrote:
>----- Original Message -----
>From: "jesse reynolds" <jesse at va.com.au>
>To: "Ruben de Groot" <mail23 at bzerk.org>
>Cc: <questions at freebsd.org>
>Sent: Friday, September 05, 2003 8:08 AM
>Subject: Re: RAID1 is DEGRADED, but which disk is faulty?
>
>
>>  Is it safe to shut it down and see what the Promise firmware
>>  is saying? Or will i then lose the ability to tell which disk is
>>  good and which has problems?
>
>I use an ASUS A7V333 board, with the onboard Promise PDC 20276 RAID
>controller (ATA133). Last summer I had the exact problem as you:
>
>ar0: ATA RAID1 subdisks: ad4 ad6 status: DEGRADED
>
>As the BIOS does a scan on the array at startup, going into the setup, it
>was immediately clear which drive was failing; and I could just rebuild from
>the BIOS (after putting in a new disk).
>
>There is also a "manual" test you could try. Simply open up your casing, and
>feel which drive is cold. :) Because after the array was degraded, ad6, in
>my case, was turned off.
>
>FreeBSD, btw, was able to boot off the degraded array as well. And, I mean,
>why not even? That is the whole purpose of RAID1. The warning messages kinda
>look scary, and make you feel your system is on the verge of collapse. But
>in reality, you just have a system running on one hard disk, like millions
>of other computers in the world. :)

Cool, so you think it's safe to reboot the machine? The promise 
controller will know which disk is the 'up to date' one will it? (In 
the event that both drives are actually OK but the mirrir has 
'broken' for some reason, perhaps they were never properly built in 
the first place - this is the first time I've run atacontrol to check 
the status!)

Thankyou

Jesse


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