Disks are currently 36GB 10kRPM SCSI ultra3 with hardware RAID (PERC 3/DI
onboard with 128MB cache)
iostat for the DB disk partition is:
avg-cpu: %user %nice %sys %idle
8.62 0.03 4.62 86.73
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz
avgqu-sz await svctm %util
/dev/sdb1 2.74 4.63 8.58 7.10 90.54 94.58 45.27 47.29 11.81
0.05 4.73 4.10 0.64
I'd say the 95-percentile for load is rather more like 1.4 than 2.
Thanks for the input,
A
On Mon, 16 Jun 2003, walt wrote:
> Andy Stubbs wrote:
> >
> > Hi, long time listener, first time caller (I think),
> >
> > I've got a database which I'm looking to increase performance, either by
> > buying bigger kit or by somehow optimising current configuration.
> >
> > I'm running MySQL-Max-3.23.56-1 from the mysql.com RPMs on a Dell
> > Poweredge 2500 with dual 1400MHz PIII processors and 4GB RAM with RedHat
> > 7.3 kernel 2.4.18-10smp.
> >
> > The database itself is actually quite small; about 3.3GB on disk. Disk
> > configuration is RAID-5, 3 disks, chunksize 8KB, default mounting options.
> >
> > Currently, when moderately busy, it's not unusual to see 400 queries/sec,
> > so I imagine when running top whack at the moment we're probably hitting
> > up to 500 selects/second. Keeping our developers focussed on how their
> > design decisions affect performance is a continual process of course...
> >
> > Anyway, the load average on this server is hitting 2 occasionally, and
> > it's time either to tune the configuration, move it onto some other kit,
> > or buy in some kit specifically. Apparently I might be looking at the
> > traffic on the database quadrupling in the next few months, so I'm keen on
> > getting this sorted ASAP.
> >
> > Having Read The Fine Manual, and being more of a coder/sysadmin than a DBA
> > I have some dumb questions. Which are:
> >
> > 1. Does anybody else have any experience with this situation? Good, Bad,
> > Ugly?
> >
> > 2. I can move this DB to a dual PE2600 with dual Xeon 1.8GHz processors.
> > and I can get up to 6GB RAM in there. Is it worth doing this? i.e., how
> > much extra capacity does this buy me? Does enabling HyperThreading on
> > the Xeons help or hinder database servers?
> >
> > 3. Would upgrading to 4.0.13 help at all? What kind of performance does it
> > have compared with 3.23.56? This is a medium term goal anyway, and
> > we'd like to take rather more time over it.
> >
> > 4. I read that on a 32 bit architecture (like these Pentium class CPUs)
> > the database tables are not memory-mapped (i.e., it's not possible to
> > store the entire database in memory anyway). Is this the case with the
> > 64 bit Solaris too? Is there a planned implementation schedule for this
> > functionality?
> >
> > 5. What's the performance of MySQL like on Solaris 8/9 compared to Linux
> > 2.4.18? Is a big multiprocessor Sun box (like a Sun Fire 880 or 1280) a
> > good choice for a database server running MySQL? Or are there more
> > suitable platforms? Is, in fact, something like a SunFire 880 overkill?
> >
> > 6. Would it be complete lunacy, in the absence of memory-mapped tables, to
> > specify a RAM-disk on which to store the database? Should improve seek
> > times, eh? And lots of redundant UPS stuff.
> >
> > 7. Any other suggestions welcome. I'm a bit nervous about turning off
> > atime on mounting the disks - is it really not used by the database
> > anywhere? what kind of performance boost does it give?
> >
> > Regards,
> >
> > Andy
> >
> > --
> > Andy Stubbs, B.A., Ph.D.
> > Network Manager, Active Hotels Ltd.
> > +44 1223 578106
> >
> Andy,
> A load avg of 2 sounds like the machine is under a high I/O load.
> Have you considered using 15k rpm drives? Is your raid setup hardware or
> software?
>
> walt
>
>
--
Andy Stubbs, B.A., Ph.D.
Network Manager, Active Hotels Ltd.
+44 1223 578106
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