Re: kernel freeze on 2.4.0.prerelease (smp,raid5)

["Otto Meier" <gf435@gmx.net>]

On Tue, 02 Jan 2001 18:19:41 +0100, Otto Meier wrote:

>>Dual Celeron (SMP,raid5)
>> As stated in my first mail I run actually my raid5 devices in degrated mode
>> and as I remenber there has been some raid5 stuff changed between 
>> test13p3 and newer kernels.

>So tell us, why do you run your raid5 devices in degraded mode?? I
>cannot be good for performance, and certainly isn't good for
>redundancy!!! But I'm not complaining as you found a bug...

I am actually in the middle of the conversion process to raid5 but it takes a while
I am to lazy :-) to get the next drive free to get raid5 into the fully running mode.  

>> Hope this gives someone an idea?

>Yep. This, combined with a related bug report from n0ymv@callsign.net
>strongly suggests the following patch.
>Writes to the failed drive are never completing, so you eventually
>run out of stripes in the stripe cache and you block waiting for a
>stripe to become free. 

>Please test this and confirm that it works.

It really did the trick you are great.
The system runs now for over a hour otherwise it would have crashed after some 
seconds (20 to 30).

btw what does this message in boot.msg mean?

<4>raid5: switching cache buffer size, 4096 --> 1024
<4>raid5: switching cache buffer size, 1024 --> 4096

the log of the raid init you find below.

Thanks again

Otto

--- ./drivers/md/raid5.c 2001/01/03 09:04:05 1.1
+++ ./drivers/md/raid5.c 2001/01/03 09:04:13
@@ -1096,8 +1096,10 @@
bh->b_rdev = bh->b_dev;
bh->b_rsector = bh->b_blocknr * (bh->b_size>>9);
generic_make_request(action[i]-1, bh);
- } else
+ } else {
PRINTK("skip op %d on disc %d for sector %ld\n", action[i]-1, i, sh->sector);
+ clear_bit(BH_Lock, &bh->b_state);
+ }
}
}

>Raid5 (3 drives actuall 2 drives degra. mode)
<6>raid5: device hdg7 operational as raid disk 1
<6>raid5: device hde7 operational as raid disk 0
<1>raid5: md1, not all disks are operational -- trying to recover array
<6>raid5: allocated 3264kB for md1
<1>raid5: raid level 5 set md1 active with 2 out of 3 devices, algorithm 2
<4>RAID5 conf printout:
<4> --- rd:3 wd:2 fd:1
<4> disk 0, s:0, o:1, n:0 rd:0 us:1 dev:hde7
<4> disk 1, s:0, o:1, n:1 rd:1 us:1 dev:hdg7
<4> disk 2, s:0, o:0, n:2 rd:2 us:1 dev:[dev 00:00]
<4>RAID5 conf printout:
<4> --- rd:3 wd:2 fd:1
<4> disk 0, s:0, o:1, n:0 rd:0 us:1 dev:hde7
<4> disk 1, s:0, o:1, n:1 rd:1 us:1 dev:hdg7
<4> disk 2, s:0, o:0, n:2 rd:2 us:1 dev:[dev 00:00]
<6>md: updating md1 RAID superblock on device
<4>hdg7 [events: 00000087](write) hdg7's sb offset: 24989696
<6>md: recovery thread got woken up ...
<3>md1: no spare disk to reconstruct array! -- continuing in degraded mode
<6>md: recovery thread finished ...
<4>hde7 [events: 00000087](write) hde7's sb offset: 24989696
<4>.
<4>... autorun DONE.





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