Date: Fri, 12 Mar 1999 18:28:22 +0100 (CET) From: Edwin Mons <e@ik.nu> To: ken@plutotech.com (Kenneth D. Merry) Cc: hardware@freebsd.org Subject: Re: SCSI ZIP slow transfers Message-ID: <199903121728.SAA13022@mag.ik.nu> In-Reply-To: <199903121718.KAA32574@panzer.plutotech.com> from "Kenneth D. Merry" at "Mar 12, 99 10:18:51 am"
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> Edwin Mons wrote... > > Hi. > > > > I use FreeBSD 3.1-RELEASE at home, and have a SCSI ZIP drive attached > > to an NCR-810 controller. When reading or writing DOS disks, I can read > > and write at 97 KB/s max. If the disk is a UFS ZIP, transfer speeds of > > 400 KB/s can be reached, but if I dd the raw data from either one of these > > two disks, speed is reduced to 97 KB/s again. After enabling CDB debugging > > for the ZIP drive I noticed that when accessing the UFS ZIP data is read > > in 64 KB blocks, while when reading raw data (with dd) or a DOS disk, the > > blocksize is 4KB. > > > > Can anybody explain this to me? I more or less expected to see the 4 KB > > blocksize when accessing the DOS partition (8 sector cluster layout), but > > I can't explain the 4 KB blocks for raw reads. > > What arguments did you use with dd? Did you specify 64k blocks when > reading from the raw device? I used `dd if=/dev/rda0 of=/dev/null bs=64k` to read the disk. I'm not at my own system at the moment, so I can't give more details (/var/log/messages, exact rates, etc.). Regards, Edwin Mons Edwin Mons | ...and the LART shall reign, and the e@ik.nu | daemons shall conquer the evil fortresses http://www.mons.net | of the beast of NT and their leagues of FreeBSD - the power to serve | management and MicroDrones... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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