Hmm... when I do what you suggest, here's what I get... tigger# dd if=/dev/ad8s1d of=/dev/null bs=64k count=100 100+0 records in 100+0 records out 6553600 bytes transferred in 0.147501 secs (44430888 bytes/sec) tigger# dd if=/dev/ad8s1d of=/dev/null bs=100k count=100 100+0 records in 100+0 records out 10240000 bytes transferred in 0.230168 secs (44489246 bytes/sec) tigger# dd if=/dev/ad8s1d of=/dev/null bs=200k count=100 100+0 records in 100+0 records out 20480000 bytes transferred in 0.429506 secs (47682693 bytes/sec)
~47MB ? huge difference I'm still not sure at this point what the best way is to evaluate whether I'm getting my money's worth out of this disk/controller. How do I do a good benchmark of the speed? Thanks, cn -----Original Message----- From: Erik Trulsson [mailto:[EMAIL PROTECTED] Sent: Sunday, August 24, 2003 7:32 PM To: Chris Newman Cc: [EMAIL PROTECTED] Subject: Re: hard disk performance issue On Sun, Aug 24, 2003 at 06:16:11PM -0500, Chris Newman wrote: > Hi, > > I have a Dell P3-500 Optiplex GX1. I was running FreeBSD 5.0 on an 8G drive. > I recently upgraded to a Western Digital ATA100 40GB drive and loaded > FreeBSD 5.1. > I expected to get improved drive performance, however, my motherboard would > only do UDMA-33. > > So, I picked up a Maxtor SATA/150 PCI Combo card. It's supposed to do > ATA-100. My dmesg > indicates that it is running UDMA-100, but my disk dump performance is still > pathetic. > > Here's a dd sample: > > tigger# dd if=/dev/ad8s1d of=/home/chris/tmp.dat count=10000 > 10000+0 records in > 10000+0 records out > 5120000 bytes transferred in 2.292473 secs (2233396 bytes/sec) > > ~ 2MB per second?? It was about 1.8MB per second before I upgraded. The only > thing > I can attribute the marginal speed-up to is the faster drive rotation speed > (7400 RPM). What do you expect when you only transfer 512 bytes with each read/write? That is a lot of overhead, and will make the actual speed of the disk to have little effect on the numbers obtained. Try increasing the block size. I.e. try: dd if=/dev/ad8s1d of=/home/chris/tmp.dat bs=64k count=100 On my system that gives about a factor of 8 faster performance. To get a better idea on how fast the disk actually is (with less overhead from the filesystem, and with less seeking involved) (and also to get bigger numbers :-) ) try sending the output to /dev/null instead of an actual file. (I.e. use of=/dev/null instead of of=/home/chris/tmp.dat) -- <Insert your favourite quote here.> Erik Trulsson [EMAIL PROTECTED] --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.408 / Virus Database: 230 - Release Date: 10/24/2002 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.408 / Virus Database: 230 - Release Date: 10/24/2002 _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"