Date: Wed, 26 Apr 2000 20:58:38 +0200 From: sthaug@nethelp.no To: kstewart@3-cities.com Cc: dillon@apollo.backplane.com, narvi@haldjas.folklore.ee, mbac@nyct.net, bright@wintelcom.net, toasty@dragondata.com, hackers@FreeBSD.ORG Subject: Re: Double buffered cp(1) Message-ID: <19282.956775518@verdi.nethelp.no> In-Reply-To: Your message of "Wed, 26 Apr 2000 11:32:53 -0700" References: <39073655.56A70C00@3-cities.com>
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> > A modern hard disk can do 10-30 MBytes/sec to/from the platter, assuming > > no seeks. But the moment it needs to seek the performance drops > > drastically ... generally down to 1-5 MBytes/sec. > > I haven't seen any 30MB/s. The 10K LVD IBM's were just about the > fastest at 20MB/s continuous. The drop for UDMA drives is to even > lower rates. The IBM DPTA-372730 will do 23 MB/s continuous - this is a 7200 RPM IDE drive with very high bit density. There are IDE drives that do more, and I certainly expect the new 36 GB 1" 10K drives to do more. > I just noticed that mine isn't showing "Tagged Queueing Enabled" is > that something I can set? The adapter is an Adaptec 2940uw. > > da0 at ahc0 bus 0 target 4 lun 0 > da0: <IBM DCAS-34330W S65A> Fixed Direct Access SCSI-2 device > da0: 40.000MB/s transfers (20.000MHz, offset 8, 16bit) > da0: 4134MB (8467200 512 byte sectors: 255H 63S/T 527C) The DCAS-34330 is quirked out - which may not always be sensible. See /sys/cam/cam_xpt.c. Steinar Haug, Nethelp consulting, sthaug@nethelp.no To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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