[rrd-users] Inquiring on how to ease disk io (linux).

[Bernard Li]

Hi Raimund:

On Tue, Jun 24, 2008 at 8:06 PM, Raimund Berger
<raimund.berger at gmail.com> wrote:

> Right now, I'm testing a workaround by stack mounting a tmpfs over the
> real rrd database directory via aufs, which pleasantly resolves the
> disk io issue. It has drawbacks though:
>
> * as data is written only to the tmpfs, all of it written since the
>  last mount/disk copy is going to be lost on crash/power outage
> * those stacking fs (aufs, unionfs) apparently provide no means to
>  automatically sync back data at specified intervals.

I am not too familiar with stack mounting -- how is your solution
different from putting all the rrds in tmpfs?

I was thinking it would be ideal to put all the rrds in a hybrid
tmpfs/regular fs where data is written to tmps and periodically synced
to the regular fs.  Most folks who put rrds in tmpfs have some cronjob
to do this incase of server crash, but ideally this could be dealt
with by some fs hooks.  Maybe using inotify or something like that.

You might also be interested in this thread over at rrd-developers:

http://www.mail-archive.com/rrd-developers@lists.oetiker.ch/msg02284.html

Cheers,

Bernard