On Thu, 28 Apr 2005, Magnus Hagander wrote:
>>> Hmm, that is interesting. I have no experience in
>> troubleshooting jails, but
>>> that server was a pgsql db server (on Gentoo Linux) prior to
>> being borg, and
>>> has been very quick under heavy loads without any I/O issues.
>>
>> I just removed svr2 as being a relay point for outgoing list
>> emails ...
>> looking at iostat 5 on that machine, the CPU was wrong close
>> to 0 idle,
>> whereas now seems to be closer to 100 ... might have been throwing too
>> much into the works ;(
>>
>> Does that make a difference for anyone?
>
> It *feels* a bit faster, but I don't have the time to run an actual
> mirror test script to check right now (will try to do that later). And
> mail relaying in general tends to load up the I/O quite a bit (lots of
> small syncs in different areas of the disk)
>
> I'm not sure what kind of hardware it's on. I did the following totally
> unscientific benchmark to get a quick figure. The comparison box is a
> three years old HP Proliant DL360 with 512Mb RAM and a RAID-1 disk set,
> that's loaded with a whole bunch of I/O intensive stuff (like mail
> relaying for about 20,000 users, several web hosts, some db etc). it
> runs linux 2.4.30 with an ext3 filesystem (totally untuned).
>
>
> Reference box:
> real 0m21.318s
> user 0m6.160s
> sys 0m17.270s
>
> borg:
> real 0m25.795s
> user 0m2.318s
> sys 0m20.453s
>
> svr2:
> real 0m33.068s
> user 0m2.226s
> sys 0m21.130s
>
>
> From this test it seems the jail has some overhead, around 20-25%. Not
> sure how to read the difference witht he reference box considering I
> don't know what hw is in Borg :) But as I said, it does *seem* a lot
> snappier now.
The overhead that is being experienced is most likely the unionfs itself,
and not the jail ... its one of the reasons I'm watching the VFS rewrite
work being done by DragonFlyBSD closely, since they plan on fixing the
bugs in unionfs, including improving its overall performance ... :(
----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664