Problems with PostgreSQL 9.0 on CentOS 6.3 with a 2.6.32-series kernel

Tue, 25 Sep 2012 13:20:36 +0000

Note: this is cross-posted from the Yodle Tech Blog. We recently migrated our Postgres database to a significantly more powerful machine. While our existing server was doing okay load-wise, we were approaching 90% full on its Postgres volume. We’d also recently acquired an awesome new PureStorage SSD-based SAN and were excited to move our database onto it. For comparison, here are the the specs for the two systems:


	Old server	New server
Nickname	DB1	DB2
CPU	2x 6-core Xeon X5690 CPUs at 3.47GHz	2x 8-core E5-2690 CPUs at 2.90 GHz
Memory	96 GB 1333 MHz	128 GB 1600 MHz
Storage	- Dell PERC H800 SAS HBA - Dell MD1220 drive enclosure - 24x 15k RPM SAS drives configured in RAID 10	- QLogic QLE2562 dual-port 8 Gbit FC HBA - PureStorage SSD-based SAN
OS	CentOS 5.6 x86_64	CentOS 6.3 x86_64
Kernel	2.6.18-238.9.1.el5	2.6.32-279.2.1.el6.x86_64

As you can probably guess, moving from spinning disk onto SSD was the centerpiece of the upgrade. We’d tested the PureStorage system pretty extensively and used it in some secondary databases and seen some amazing improvements. We were excited to see how it would handle our production workload.

Benchmarking disk IO on ext3 vs ext4 vs xfs with fio

Fri, 22 Jul 2011 07:15:05 +0000

With the old database phased out, I figured this was a good time to benchmark IO on it before either repurposing it or mothballing it. In the past I’ve used dd for elementary sequential read/write testing, but I recently found fio which is much more versatile. Apparently developed by FusionIO, fio lets you control concurrency, blocksize and many other parameters and reports lots more data, most notably IOPS.

I created 4 fio config files, basically the same as the one below, for direct / buffered disk access and sequential / random writes. All have 8k blocksize since that’s what Postgres uses by default.

Io on Evan Hoffman

Problems with PostgreSQL 9.0 on CentOS 6.3 with a 2.6.32-series kernel

Benchmarking disk IO on ext3 vs ext4 vs xfs with fio