How fast is the link to your SAN? If it's Gigabit, then 80MB/s would be pretty reasonable. Also SANs are normally known for very good random access performance and not necessarily for fast sequential performance. On Mon, May 21, 2012 at 8:17 AM, Jan Nielsen <jan.sture.nielsen@xxxxxxxxx> wrote: > This is outside of PG performance proper, but while testing pg_dump and > pg_restore performance on local-storage versus SAN storage I noticed a big > performance drops on in the SAN configuration. I'm told that both local > storage and SAN storage are 15k drives with local-storage running dual RAID1 > configuration while HP StorageWorks SB40c SAN is 10x15k RAID1+0. Running a > hdparm -tT tests with different read-ahead, I see the following differences > on /dev/sda (local-storage) and /dev/sdc (SAN storage). I'm shocked at the > drop in buffered disk read performance 150MB/sec versus 80MB/sec and > surprised at the SAN variability at 1MB/sec versus 10MB/sec, local-storage > and SAN storage respectively. > > For those who, unlike me, have experience looking at SAN storage > performance, is the drop in buffered disk reads and large variability the > expected cost of centralized remote storage in SANs with fiber-channel > communication, SAN fail-over, etc. > > If you have any ideas or insights and/or if you know of a better suited > forum for this question I'd sure appreciate the feedback. > > > Cheers, > > Jan > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance > -- To understand recursion, one must first understand recursion. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
