gsk@khaki (10/06/87)
sounds like you guys have done some excellent work.
can anybody tell me what interleave (and step rate?) to use with
the DTC 5150BX controller (the one AT&T OEMs from DTC) and an ST225
on my 6300 running DOS 3.2 ?
once i know what parameters to use, how do i do a low-level format with them?
(the DTC ROM formatting routines don't ask you for any parameter values)
data for other drives with the above system are also of interest to me,
since i'm thinking about adding another drive to my system.
while we're on the subject of disk performance, has anyone compared
various controllers against each other w.r.t. performance?
is anyone successfully using controllers that do whole-track buffering,
caching, etc?
George S. Kong, Silicon Graphics, Inc., (415)962-3281
gsk@sgi.com
...{decwrl,allegra,sun,adobe,ucbvax,pyramid,ames}!sgi!gskpgf@mtung.ATT.COM (Paul Fox) (10/07/87)
Speaking of interleaves, I thought I'd pass this tidbit on to all you performance hounds... The default filesystem interleave on the 7300/3B1 is 1. I don't know what the low-level interleave is. If the filesystem interleave is changed to 4 (either for the whole disk by modifying the mkfs parameters in the floppy boot code, or for the freespace only, by doing as fsck -S (is that right? rt*m)) then data transfer rates go up quite a bit. I.e., copying /unix to /dev/null takes about half the time it used to. Note that UNIX filesystem interleaves decay with time for the non-static part of the filesystem, since the freelist is not sorted, and blocks slowly get shuffled. Also, since it is a paging system, not all of an executable is read at once, so it's not clear what the win is for commands. Data access behaviour affects disk performance a lot, of course. Anyway, I thought I'd mention it, in case anyone wanted to play with it. Let us know your results... -- Paul Fox, AT&T Information Systems, Middletown NJ. [ihnp4|vax135]!mtung!pgf (201)957-2698
dpbaudra@ihlpe.ATT.COM (Braune) (10/07/87)
In article <6699@sgi.SGI.COM> gsk@khaki writes: >can anybody tell me what interleave (and step rate?) to use with >the DTC 5150BX controller (the one AT&T OEMs from DTC) and an ST225 >on my 6300 running DOS 3.2 ? A colleague has expeience with the following in a PC6300: ST225/DTC5150BX IL=5 ST238/Adaptec RLL IL=5 Proper step rate is still an issue however a Seagate book now in my possession says ST225/238 disks can accept step rate pulses from 5usec to 200usec. First try would be to shoot for anything close to (but equal to or greater than 5usec). >once i know what parameters to use, how do i do a low-level format with them? >(the DTC ROM formatting routines don't ask you for any parameter values) I'm told that some people have called AT&T and received a disk with a pgm called LOWFORM.EXE that is menu driven and will permit such parameter control. >data for other drives with the above system are also of interest to me, >since i'm thinking about adding another drive to my system. Miniscribe 3425/WD RLL IL=7 >while we're on the subject of disk performance, has anyone compared >various controllers against each other w.r.t. performance? >is anyone successfully using controllers that do whole-track buffering, >caching, etc? >George S. Kong, Silicon Graphics, Inc., (415)962-3281 >gsk@sgi.com >...{decwrl,allegra,sun,adobe,ucbvax,pyramid,ames}!sgi!gsk I have no data but would also like to see some. Dave Braune AT&T ihnp4!ihlpe!dpbaudra