newton@cs.utexas.edu (Peter Newton) (02/07/90)
I just bought an Ehman 45 external hard drive for my MacPlus with one
Meg of RAM. The disk came preformatted by Ehman. Ehman's formatting
program said that the interleave was 3:1 (correct for MacPlus). I
measured the performance of the disk several ways, and concluded that
it was quite slow. A friend suggested that I reformat the disk with a
different formatting program. I tried SilverLining (La Cie) and
noticed a dramatic speed up. I then installed SCSI-Accelerator and
saw still more improvement. Next, on the advice of SilverLining, I
tried reformatting with 2:1 interleave (on a MacPlus!). The Ehman
formatter did not succeed at updating the driver after this, but
SilverLining did. The result was still better speed, but
SCSI-Accelerator no longer helped.
After all of this, final speed up is about 2.5X, on average. Some
measures improved by as much as 5X. See table below. It is
interesting that the low level results from SCSI-Evaluator are less
dramatic than higher level measures. Anyone know why?
The moral of all of this is that it may pay to fiddle a bit with your
hard drive, especially if it is from Ehman. It pays to consider software
quality when picking a disk. If you have to buy a different formatting
program, that adds to the cost.
Formatted SilverLining SCSI- SCSI- SCSI- SilverL
by Blind Mac accel accel accel 2:1
Ehman xfer 0-0-6 1-1-5 3-3-5 Interleave
Disk Timer II
Read 132 dsec 119 98 98 232 69
Write 356 dsec 132 98 99 237 69
Seek 16 msec 18 17 17 16 16
Copy Large File* 27 sec 14 11 11 25 10
SCSI-Evaluator
Read 1500 KB/s 1500** 1600** 2500
Write 1500 KB/s 1500** 1600** 2500
Seek 33 msec 33 32 33
* no disk fragmentation
** approximate.
By the way, I am not displeased with Ehman. Their software is
inferior, and the drive is on the slow side even after all of this,
but they sent it promptly, it appears to work just fine, and has a two
year warranty. You get what you pay for. I have no connection (other
than customer) with any of the companies involved.
---
Peter Newton
Computer Sciences, TAY 2.124 (512) 471-9735
University of Texas at Austin newton@cs.utexas.edu
Austin, TX 78712-1188 ...{uunet|gatech|ames}!cs.utexas.edu!newton