toms@oakhill.UUCP (Thomas Spohrer) (07/21/87)
I would like to experiment with different interleaves on my hard disk
but I found out that I do not know how to modify the format.
I was under the impression that the interleave factor was specified
by the low level format but I find that the low level format program supplied
with the disk and controller does not have any options to allow me to specify
a different interleave factor.
Would someone please enlighten me as to how I might change the
interleave either given the software I have or any other suggested software.
Hardware:
20 MB CMI-3426 CMI Hard disk drive (ST506/412)
WD1002S-WX2 Western Digital Drive controller
IBM-PC 640k, 1 Floppy
Orchid Turbo EGA (7.2 MHZ 286).
Software:
FDI.COM Low level formatter, came w/ drive&controller
DOS 2.1 FDISK and FORMAT.
Thanks in advance.
--
=============================================================================
Motorola Semiconductors Tom Spohrer
Austin, Texas {seismo,gatech,ihnp4}!ut-sally!oakhill!tomshundt@wind.bellcore.com (tom hundt) (07/23/87)
Modifying the interleave entails reformatting from scratch
(low level, even). On most controllers, you can use their
format routine by doing:
DEBUG
g=C800:5
and proceed from their, following directions on screen or
docs.
Some controllers use addresses like C800:CCC (Adaptec) or
C800:7.
The Advanced Diagnostics bypass this procedure.
On an XT the lowest you can (supposedly) go is 3, although
I haven't really played with it much. (Anyone out there have?)
/=^=\ Thomas M. Hundt / BELLCORE Morristown NJ / hundt@bellcore.bellcore.com
| | {seismo|ihnp4|ucbvzx|decvax|ulysses|allegra|clyde|princeton}...
/--_--\ ...!bellcore!hundttimothym@tekigm2.TEK.COM (Timothy D Margeson) (07/23/87)
Hi,
To format a hard disk using a Western Digital controller:
Put your DOS disk in A: (whichever diskeete has debug on it).
A:
debug
-rax
AX XXXX
:02
-g=c800:5
'ALL THE GOOD STUFF ABOUT FORMATTING THE HARD DISK'
The above entries will set the interleave to 2 (the value placed in AX),
although for a WD1002, 3 is the best it can do on a good day, and 4 if you
have an 8086 based machine.
Good luck...
--
Tim Margeson (206)253-5240
PO Box 3500 d/s C1-937 @@ 'Who said that?'
Vancouver, WA. 98668
{amd..hplabs}cae780!tektronix!tekigm2!timothym (this changes daily)epb19@uiucuxe.cso.uiuc.edu (07/24/87)
For very little cash, or maybe even free if you sweet talk them enough, you can obtain a new "super ROM bios" chip for your controller, I am typing this msg through such a machine with one now. Then when you reformat, you can choose either to format from prearranged tables, or from your own input, and can choose various interleaves. Put something on it and run nortons or something to see how you are doing. When the interleave is too low, the effects should be extremely noticeable. Note: when putting drive in faster machine, higher interleave may be necessary to achieve same performance to counteract higher chip speed. call Michael J. Smith at Western Digital Teach Support. He knows it all. The number is: western digital 1-800-847-6181 Mike J. Smith x 3400. You may have to ask the operator to get through for you x3400 is a very popular extension.
alang@masscomp.UUCP (Alan Groupe) (07/25/87)
In article <952@oakhill.UUCP> toms@oakhill.UUCP (Thomas Spohrer) writes: > > I would like to experiment with different interleaves on my hard disk >but I found out that I do not know how to modify the format. > > I was under the impression that the interleave factor was specified >by the low level format but I find that the low level format program supplied >with the disk and controller does not have any options to allow me to specify >a different interleave factor. > > [ I have a ] > WD1002S-WX2 Western Digital Drive controller The interleave factor is specified when running the low level format routine that is in the ROM on the WX2 controller. The problem is that there are probably over 50,000 systems with a WX2 controller, EACH with a different version of the ROM. (In fact, seriously, of all my friends with WX2 contollers, none of us have the same version of the ROM). Western Digital, however, seems to be a responsive company, and you could try asking them for whatever version they think is the latest. Alan
Dion_L_Johnson@cup.portal.com (07/28/87)
I recall some results (from a source I have forgotten) that found that changing the interleave away from 1:1 made very little difference in performance. Anyone know more? Is there a reason besides performance why we would want to change the interleave?
rps@homxc.UUCP (R.SHARPLES) (07/29/87)
In article <553@cup.portal.com>, Dion_L_Johnson@cup.portal.com.UUCP writes: > I recall some results (from a source I have forgotten) that found > that changing the interleave away from 1:1 made very little > difference in performance. Anyone know more? Is there a reason > besides performance why we would want to change the interleave? The interleave is the measure of whether consecutive data is stored in consecutive sectors. 1:1 interleave means consecutive data is stored in physically consecutive sectors. If the head is finished reading sector 1 (example) but the controller has not passed all the data on to the CPU yet, it must wait before reading sector 2 (S2) (the next sector with data for 1:1 interleave). Since S2 is physically right after S1, the head will have to wait a full drive revolution before S2 comes around again. However if the interleave was 1:2 (or 2:1?) the data would be recorded in every other sector: S1-S3-S5-etc.. Then the head will read S1 and while S2 is passing underneath the controller will finish passing S1 data. Just as the controller is done S3 will start to pass under the head and it will be read on schedule. An interleave of 1:3 means that every third sector is read consecutively, 1:4 every forth. The average Seagate 225 with WD controller uses and interleave of 1:3. 1:4 is recommended on 8086 machines for some reason. If interleave is too SMALL, eg. less than 1:3, the head will always have to wait for the drive to make a full revolution between reading consecutive sectors and hence will slow the data transfer rate. For example: an ST225 w/WD controller with 1:3 interleave on a PC6300 will have a transfer rate of about 25Kb/sec. With 1:4 the transfer rate will rise to about 160Kb/sec. That is the difference between catching the next sector and waiting a full revolution. You won't really notice this unless you are moving a lot of data onto and off of the disk. To load an 80K program will take 3 seconds with the 1:3 interleave or .5 seconds with the 1:4 interleave. It is a personal choice whether this difference matters. Russ Sharples homxc!rps NOTE: The above in NO WAY reflects the opinions of AT&T. These opinions are my own and the results of un-scientific and highly irregular analysis methods.
keithe@tekgvs.TEK.COM (Keith Ericson) (07/31/87)
In article <796@homxc.UUCP> rps@homxc.UUCP (R.SHARPLES) writes: >For example: an ST225 w/WD controller with 1:3 interleave on a PC6300 >will have a transfer rate of about 25Kb/sec. With 1:4 the transfer >rate will rise to about 160Kb/sec. On my 8MHz, no-wait-state 286 AT Clone I get essentially these same transfer rates but at interleaves of 1:2 (29 KBytes/sec) and 1:3 (162 Kbytes/sec). I'm in the process of evaluating Western Digital's WD-1006-WAH which has track-buffering and can do a 1:1 interleave. The one I had (but returned for other reasons) moved data in/out at 448 KBytes/sec. At that point it's competitive with a RAM-drive. Well, almost... :-) A drawback with the WD_1006-WAH is that it is only a hard-disk-drive controller, and requires the use of a separate floppy controller. My WD rep sez that an updated version is due out RSN that combines both onot a single card. I'll let you know... PS - price is not outrageously greater than a run-of-the-mill WD-1003-WA2 (or clone). keith
ayac071@ut-ngp.UUCP (08/01/87)
In article <2503@tekgvs.TEK.COM> keithe@tekgvs.UUCP (Keith Ericson) writes: >I'm in the process of evaluating Western Digital's WD-1006-WAH which >has track-buffering and can do a 1:1 interleave. Can some kind soul e-mail (or post) me an explanation of track-buffering. Does this input in an entire track for each read. And does this actually slow down through-put on a fragmented disk? And is this the technique used on IBM's PS/2 line. And ... (oh, shut up already!!) Thanks, Bill Douglass ayac071@ngp.UUCP