Date: Fri, 12 Mar 1999 17:08:06 +0100 (CET) From: Edwin Mons <e@ik.nu> To: hardware@FreeBSD.ORG Subject: SCSI ZIP slow transfers Message-ID: <199903121608.RAA12613@mag.ik.nu>
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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. 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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