Cyrus dies

[Colin Bruce]

Dear Sebastian,

Thanks for the info especially the configuration suggestions from RedHat.
We use a modified Slackware 9.1 installation with lots of our own stuff
and a kernel we build ourselves. I just checked and we don't have a file
called /proc/sys/vm/pagecache. There are two files called pagetable_cache
and page-cluster which have "25   50" and "3" in them respectively. I
suspect that taken together they are the same as pagecache. I'll try
changing them tonight when there are not too many people around.

Anyway, thanks again for the info.

Best wishes....
Colin


On Fri, 28 May 2004, Sebastian Hagedorn wrote:

> Hi,
>
> --On Donnerstag, 27. Mai 2004 19:54 Uhr +0100 Colin Bruce
> <ccx004 at coventry.ac.uk> wrote:
>
> > I have found out the cause of this problem but I don't know what the
> > solution is. The good news from your point of view is that it isn't
> > anything to do with Cyrus - its our backup software.
> >
> > The backup cycle starts at 9PM and the problem we are experiencing starts
> > about 17 minutes later and finishes 20 minutes after that. The backup
> > is still running at that point and continues for another 30 minutes or
> > so. It didn't seem to be strongly related. However, I tried doing a manual
> > full backup and that didn't cause a problem so I tried a manual
> > incremental backup and that killed the server. I had top running at the
> > time with 1 second delays between updates but it froze. However, it was
> > showing kswapd at the top with 99% CPU time and bpkar second with 56%.
> > When I killed the backup the imap system continued happily.
>
> we have seen similar problems using TSM (Tivoli Storage Manager) backup
> software. See also below.
>
> --On Donnerstag, 27. Mai 2004 13:19 Uhr -0600 Michael Loftis
> <mloftis at wgops.com> wrote:
>
> > Linux has a LOT of known problems with huge amounts of memory...try
> > reducing your memsize to 3Gb or 4Gb either by physically pulling chips or
> > memsize=<blah> on the boot line Lilo you can say something like 'linux
> > memsize=4096M' in GRUB you have to use 'e' to edit one of the options,
> > then scroll down to the line containing kernel.... and add memsize= to
> > the end of it by 'e' editing that line, then you can use b to boot.  See
> > if that helps your performance.
>
> This I can confirm. We have Dell 6450 systems with 8GB of RAM and the
> caching has caused us no end of problems. Recentyl we reduced the memory to
> 2 GB and things are better. However, now, after two years of problems we
> reported to Red Hat, they finally came up with a suggestion about how to
> tune the kernel, albeit somewhat vague: they recommended we lower the
> values in /proc/sys/vm/pagecache. On RH AS 2.1 they default to:
>
> 2       50      90
>
> We have now reduced them to:
>
> 2       10      60
>
> Hmm, I just noticed that the RH AS 3 values default to:
>
> 1       15      100
>
> Things *seem* to be working better this way, but we'll have to see ...

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