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

[Raimund Berger]

Ronan Mullally <ronan at iol.ie> writes:

> A few suggestions that I've tried on different systems in the past:
>
>  - Upgrading your disk system is an obvious choice - more disks
>    RAID 1 (or 0 if you live dangerously) and a caching RAID controller
>    will help definitely help.
>
>  - Tweaking your underlying filesystem to take advantage of a RAID
>    filesystem can make a difference - I've seen big improvements using
>    the stride-size and stripe-width options to mke2fs (though that was
>    on a mail spool, not RRD files).
>
>  - Tweaking some of the kernel attributes in /proc/sys/vm will change
>    when and how often data cached by the OS will be written to the disk
>    (or the cache in the disk controller).  I found this helped slightly
>    on a filesystem with about 5,000 RRDs being hit every 5 minutes.
>
>  - Tweaking the disk scheduler parameters in /sys/block/<disk>/queue can
>    improve things a bit, depending on your traffic profile.
>
> I hope these are useful.  The last 2 can be tried on the fly.  The others
> require downtime.


Good hints. Up to now I've been investigating mainly application local
tweaks (like that rather promising RRDCache approach), but system wide
tweaks might be a nice alternative/addon too, albeit of course leading
to tradeoff situations.

Thanks a lot for the input,
R.