davecb at Canada.Sun.COM
Thu Feb 4 13:24:25 GMT 1999
Denis Sbragion wrote:
> Are you sure about this? I benchmarked about 12 Mb/s of transfer rate on a
> recent IDE drive (Fijitsu 10 Gb, Linux 2.0.36, PII 266, Asus MB).
The maximum throughput of a drive, if reading purely sequentially,
is a simple factor of bit-density/track and rotational speed...
Adrian Cockroft provides data for a 5400 rpm disk, using a
seek-rotate-read scenario, that gives 432 KB/S and a response time
of 19ms [In Sun Performance & Tuning, 2nd ed p207]. This is
reasonable: by counting start-ios I got 60/sec, and 480 KB/S with
8 KB reads.
I like the old approach of counting startios on a real system:
(iostat's tps column). This is an old DEC/IBM measure, and
is easy enough to do.
You may be measuring buffering on your fast disk: I've seen
some amazing transfer rates for slow devices which can do
full-track reads. This is A Good Thing, but you need to lay
our the data to avoid much seeking.
By the way: I'm used to getting very different results in seemingly
similar tests... vendors make it hard to compare their stuff (:-))
--dave (I hate all vendors: I am a vendor) c-b
David Collier-Brown, | Always do right. This will gratify some people
185 Ellerslie Ave., | and astonish the rest. -- Mark Twain
Willowdale, Ontario | http://java.science.yorku.ca/~davecb
Work: (905) 477-0437 Home: (416) 223-8968 Email: davecb at canada.sun.com
More information about the samba