On 20/05/12 03:47, Jan Nielsen wrote:
In this test, the local mount's buffered reads perform best around RA~10k @ 150MB/sec then starts a steady decline. The SAN mount has a similar but more subtle decline with a maximum around RA~5k @ 80MB/sec but with much greater variance. I was surprised at the 80MB/sec for the SAN - I was expecting 150MB/sec - and I'm also surprised at the variance. I understand that there are many more elements involved for the SAN: more drives, network overhead& latency, iscsi, etc. but I'm still surprised. Is this expected behavior for a SAN mount or is this a hint at some misconfiguration? Thoughts?
Is the SAN mount via iSCSI? If so and also if the connection is a single 1Gbit interface then 80MB/s is reasonable. You might get closer to 100MB/s by tweaking things like MTU for the interface concerned, but to get more performance either bonding several 1Gbit links or using 10Gbit is required.
Regards Mark -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
