Subject: Expected SCSI transfer rates?
To: None <>
From: Thomas Klausner <>
List: netbsd-users
Date: 12/23/1999 00:38:42

I'm currently copying files around on NetBSD-1.4.1/i386, and wondered
why it takes so long. I have a SCSI-only system (Adaptec 2940UW), and
in this special case I was copying from one disc with an ext2fs to an
msdos-system on another disc, and got about 300kb/s. When I started
another copy parallel from the same ext2fs to a 4.2BSD(ffs) partition,
both transfer rates got down to about 70kb/s each.

The dmesg output for the devices & bus is attached below.

Is this as fast as it gets, or could it be faster?

In another test I was copying from an msdos fs on my (also SCSI-)ZIP
drive to the same msdos partition, and got about 90kb/s. I remember,
once about a time, when I was still running NT, that I got _much_
higher transfer rates (about triple that, IIRC).

Any comments?

While we're at it, why is my spanking new sd5 LVD-W-whatever drive the
only one with 10MHz? Oh, forgot to mention: sd0 and sd5 are on the
wide part of the controller, the rest on the ordinary/ultra part.

Thanks for all hints,

sd3 is the zip, the other msdos fs is on sd0, the ext2fs on sd4, the
ffs on sd5.


ahc0 at pci0 dev 9 function 0
ahc0: interrupting at irq 9
ahc0: aic7880 Wide Channel, SCSI Id=7, 16 SCBs
scsibus0 at ahc0 channel 0: 16 targets, 8 luns per target
ahc0: target 0 using 16Bit transfers
ahc0: target 0 synchronous at 20.0MHz, offset = 0x8
sd0 at scsibus0 targ 0 lun 0: <IBM, DDRS-39130D, DC1B> SCSI2 0/direct fixed
sd0: 8715MB, 8387 cyl, 10 head, 212 sec, 512 bytes/sect x 17850000 sectors
ahc0: target 1 synchronous at 20.0MHz, offset = 0xf
sd1 at scsibus0 targ 1 lun 0: <QUANTUM, FIREBALL ST4.3S, 0F0C> SCSI2 0/direct fixed
sd1: 4136MB, 7068 cyl, 6 head, 199 sec, 512 bytes/sect x 8471232 sectors
ahc0: target 3 synchronous at 20.0MHz, offset = 0xf
cd0 at scsibus0 targ 3 lun 0: <TOSHIBA, DVD-ROM SD-M1201, 1R08> SCSI2 5/cdrom removable
ahc0: target 4 synchronous at 20.0MHz, offset = 0xf
sd2 at scsibus0 targ 4 lun 0: <QUANTUM, XP34550S, LXY4> SCSI2 0/direct fixed
sd2: 4341MB, 5899 cyl, 10 head, 150 sec, 512 bytes/sect x 8890760 sectors
sd3 at scsibus0 targ 5 lun 0: <IOMEGA, ZIP 100, N*32> SCSI2 0/direct removable
sd3: drive offline
ahc0: target 6 synchronous at 20.0MHz, offset = 0xf
sd4 at scsibus0 targ 6 lun 0: <QUANTUM, FIREBALL_TM2110S, 300X> SCSI2 0/direct fixed
sd4: 2014MB, 6810 cyl, 4 head, 151 sec, 512 bytes/sect x 4124736 sectors
ahc0: target 12 using 16Bit transfers
ahc0: target 12 synchronous at 10.0MHz, offset = 0x8
sd5 at scsibus0 targ 12 lun 0: <QUANTUM, ATLAS IV 18 WLS, 0909> SCSI3 0/direct fixed
sd5: 17522MB, 13816 cyl, 8 head, 324 sec, 512 bytes/sect x 35885168 sectors

Thomas Klausner -
Der Horizont vieler Menschen ist ein Kreis mit Radius Null -- und
das nennen sie ihren Standpunkt. (found on /.)