On Mon, 16 Feb 2004, ian sison (mailing list) wrote: .. > per controller. The object of the exercise is to make sure that the bus > doesn't become a bottleneck assuming a drive can churn out 33-40MBps > from platter to the underlying drive electronics.
but when doing random read/write, the drive's performance does not approach the burst speed, but the I/O's per second. A drive doing 100 I/O's per second is a fast drive (10ms seek time). but since UNIX generally uses 4K file blocks, and file I/O is most often just one block at a time (due to mmap) then your actual drive bandwidth for a very busy drive is more like 4K x 100 I/O/s per second = 400K/second. Which is nowhere near 40Mbps. translation.. with SCSI you can put at least 10 drives on a single controller, assuming the application has lots of small files and lots of random seek (true of Squid and email servers). with IDE you can't because IDE is a bus-mastering interface (vs a packet-based interface) so IDE can't "slice up" the bandwidth as efficiently as SCSI can. --- Orlando Andico <[EMAIL PROTECTED]> Mosaic Communications, Inc. -- Philippine Linux Users' Group (PLUG) Mailing List [EMAIL PROTECTED] (#PLUG @ irc.free.net.ph) Official Website: http://plug.linux.org.ph Searchable Archives: http://marc.free.net.ph . To leave, go to http://lists.q-linux.com/mailman/listinfo/plug . Are you a Linux newbie? To join the newbie list, go to http://lists.q-linux.com/mailman/listinfo/ph-linux-newbie
