Re: 2.4.9-ac1 RAID-5 resync causes PPP connection to be unusable

Doug Ledford
2001-08-30T18:00:00Z

Kevin P. Fleming wrote:

> I ran into a very strange problem yesterday... my server here, which is a
> 700 MHz Celeron, 256MiB RAM, four ~40G disks has two RAID-5 arrays (using
> the standard kernel MD driver) configured across those four drives. For some
> reason definitely related to operator error, the machine crashed and needed
> to resync the arrays after being rebooted.
>
> Eveything was working fine, interactive response was just fine even though
> the drives were just cranking away doing their resync. I then brought up my
> PPP Internet connection, which came up just fine. However, I was _not_ able
> to actually communicate with any 'Net hosts.

[ snip ]

> I can probably reproduce this pretty easily, if anyone is interested and can
> give me some idea where to look for the cause...

Don't bother. The problem is that your disks are IDE disks and you
don't have IRQ unmasking enabled on some/all of them. As long as that's
the case, heavy disk activity (whether it's a RAID5 resync or a bonnie
run or untar'ing a kernel archive) will always cause your PPP connection
to quit working due to dropped serial data and therefore corrupted PPP
packets.

--

Doug Ledford <dledford@redhat.com> http://people.redhat.com/dledford
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