Re: No buffer space available

[Tom Ivar Helbekkmo <tih%hamartun.priv.no@localhost>]

Rich Neswold <rich.neswold%gmail.com@localhost> writes:

> I just got a hold of a pair of Dell 2850s and, while building from source,
> the system "froze" for several minutes. It eventually recovered. The logs
> didn't show anything unusual (like out of buffers), so I didn't pursue it
> aggressively. Doing a CVS checkout of PKGSRC also caused it, so it seems
> related to very high, write traffic. These systems have AMI Hardware RAID
> controllers (amr driver) and I figured when the write cache got full, it
> prevented any other disk I/O until the writes finished. I rebooted and went
> into the BIOS and shut off the write cache. I haven't seen the problem
> since, but I became busy with other projects and haven't tried to diagnose
> it further.

It seems you've got it.  I turned off the delayed write functionality of
the cache on my 2850, and the problem has gone away.  To test it, I
loaded the system down much more than previously, with various tasks,
each of which has triggered the unwanted behaviour in the past: I ran a
full build from source with "-j 4", and after observing for a while that
that caused no problems, I added a full backup, a busy bittorrent
client, and NFS service for another system build running on a client
system.  Still no hangs, and this sort of load would have ended with me
hitting the power button to regain control over the box in the past.

-tih
-- 
It doesn't matter how beautiful your theory is, it doesn't matter how smart
you are. If it doesn't agree with experiment, it's wrong.  -Richard Feynman