On Fri, 10 Oct 2008, Gregory Stark wrote:
They don't quote sustained bandwidth for consumer drives but 50-60MB/s are the numbers I remembered -- admittedly from more than a couple years ago. I didn't realize 7200 RPM drives had reached such speeds yet.
The cheap ($42!) 7200RPM SATA disks I bought a stack of for my home server hit a sequential 110MB/s at the beginning edge, at the other end throughput is still 60-70MB/s. The smaller capacities of Seagate's 7200.11 average about 100MB/s nowadays. But by the time you seek to a location (8-9ms) and line the heads up (half a rotation at 7200RPM averages 4ms) you can easily end up at 12-13ms or higher measured access time on random reads with those. So the true random/sequential ratio reaches crazy numbers.
I don't think random_page_cost actually corresponds with any real number anymore. I just treat it as an uncalibrated knob you can turn and benchmark the results at.
-- * Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
