Justin Gledhill wrote:
Hi All
I need some config suggestions for UniVerse (9.6.2.8) and Win2k to maximise
I/O. A customer is currently experiencing problems with SSELECTS when their
server is under load. Files concerned are large but types and sizing have
been addressed.
Particular areas of their application causing the issues have been
identified as initiating a lot of I/O... SSELECTS, setting and releasing
locks etc etc. SELECTS, LISTS, COUNTS of same files are fine.
Not much info I know and I realise these things can be very site specific.
However in the first instance i'm just after some generic tips/suggestions
re windows and uvconfig tunables.
Others can respond with config tunables, but this is usually just a
matter of IOPS (IOs Per Second) and disk subsystems.
1. Use 15K disks. This will give you about 225 random reads per drive.
1a. The brand or format of 15K drives only accounts for 2-5%
performance variance, so don't get too fancy.
2. Use lots of disks. If you have lots of users competing, lots of
disk help. Unfortunately, if you need to speed up the runtime of a
single batch job, lots of disks does not translate into faster run times.
2a. Buy good hot-swap chassis and be sure to pay your air conditioning
bill.
3. Keep a fast disk channel. With lots of drives, this usually means
SAS for current servers. It could also be FC, but FC is more expensive
than SAS and not any faster. It is however "longer reach", so useful in
large settings.
4. Keep UV volumes on different disks from other windows applications.
5. Run RAID-1 or RAID-10, not RAID-5. Raid-5 has very poor random
write performance and even small numbers of random writes can keep the
whole array busy.
6. More small drives are better than fewer large drives.
If this is still not enough, you are looking at "new" storage
solutions. I could kick into an advert here, but that is not really my
purpose (while, if you want to see the ad anyway, try
http://managedflash.com). These include various "solid state" storage
alternatives. Expect the cost/GB to be from 2x to 500x more than you
would expect to pay for hard disks. On the other hand, you can get 8000
random 4K read/write IOPS from a single flash drive at about $70/GB and
>50,000 random read IOPS from a DRAM disk appliance at more than
$800/GB. If you want to discuss this, start up a new thread and I will
be happy to talk about our Linux / Flash drive experiences with
Universe, D3, and OpenQM.
Doug Dumitru
EasyCo LLC
Cheers
Justin
Justin Gledhill
Uniware Pty Ld
(T) +613 8804 0804
(F) +613 8804 0805
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