From: | Brian Ghidinelli <brian(at)pukkasoft(dot)com> |
---|---|
To: | SF Postgres <sfpug(at)postgresql(dot)org> |
Subject: | 8.2 slower than 8.1? |
Date: | 2007-12-28 01:43:16 |
Message-ID: | 477454B4.6030201@pukkasoft.com |
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Thread: | |
Lists: | sfpug |
About 2 years ago, I ran some benchmarks on a Compaq DL380G2 I use for
Postgres[1]. I tested a variety of disk configurations to compare
setups. I'm rebuilding the machine now with upgraded hardware and I'm
dumbfounded by substantially slower performance. Here are the specs:
Compaq DL380G2, 2x1.44ghz, six internal disks with Smart Array 5i
controller.
Prior Now
-------------------------------------------------------------------
OS CentOS 4.2 CentOS 5.0
Filesystem ext3 ext3
postgresql.conf Stock Stock
Ram 1 GB 3 GB
Postgres 8.1.2 8.2.5
Smart Array 5i (builtin, 16mb) 5302 (128mb cache)
Drive Config 2 disk RAID-1 (os/log) 2 disk RAID-1 (os)
4 disk RAID-10 (data) 4 disk RAID-10 (log)
14 disks RAID-10 (data)
I'm using the six internal disks as a 2-disk raid-1 mirror for the OS
and 4-disk raid-10 for the log on the internal 5i controller. I have an
external 14-disk raid-10 connected to a Smart Array 5302 (with 128gb
cache in a 75%/25% read/write setup).
I ran my benchmark script again (see below) and the performance dropped
60% at 1 and 2 users and 27% and 17% at 5 and 10 users respectively.
Any ideas what might lead to this decrease across the board?
Brian
[1] http://www.ghidinelli.com/2006/01/17/postgres-812-benchmarks/
Here is my simple script:
#!/bin/sh
# pgb.sh
HOST=localhost
USER=postgres
DB=testdb
totxacts=1000
for c in 1 2 5 10
do
echo "Starting test for $c users..." 1>&2
echo "== $c concurrent users, 500 transactions =============="
dropdb testdb -U $USER
createdb testdb -U $USER
echo "Initializing benchmark database"
pgbench -i -U $USER -s 10 testdb &> /dev/null
echo "===== sync ======"
sync;sync;sync;sleep 10
pgbench -n -U $USER -t 500 -h $HOST -c $c $DB 2>&1
done
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