slimer@trsvax.UUCP (08/10/89)
I used to do this alot... let's see... I believe the problems could be the fact that a TYPE 2 does not represent a 20MEG drive. The drive TYPEs represent the number of cylinders and heads on the physical drive. What you would need is a list of the TYPEs by cylinder and head numbers, then compare your new drive to these TYPEs to find the correct match. Of Course...this is only one item that could be the problem. I know that in some machines I have worked on... a IBM OLD 20MEG is a TYPE 2 while some newer 20MEGs by third parties are TYPE 4. Check it out...could be... **************************************************************************** * Thank You, texbell!letni!rwsys!trsvax!slimer * * Bill "Icon do windows!" - ComputerWorld * * George W. Pogue, 1300 Two Tandy, Fort Worth, TX. 76102 (817) 390-3562 * ****************************************************************************
kaldis@topaz.rutgers.edu (Theodore A. Kaldis) (08/15/89)
In article <216100121@trsvax> slimer@trsvax.UUCP writes: > I used to do this alot... let's see... I believe the problems could be > the fact that a TYPE 2 does not represent a 20MEG drive. The drive TYPEs > represent the number of cylinders and heads on the physical drive. > What you would need is a list of the TYPEs by cylinder and head numbers, > then compare your new drive to these TYPEs to find the correct match. > Of Course...this is only one item that could be the problem. I know that > in some machines I have worked on... a IBM OLD 20MEG is a TYPE 2 while > some newer 20MEGs by third parties are TYPE 4. Are you certain about this? I was under the impression that all clones use the same numbers to designate drives. Type 2 is a 615 cyl., 4 head, 17 sect. drive with 300 precomp. (the setting used for for Seagate 225's). Type *6* is also a 20 meg with the same specs, except no precomp. (Type 4 is a 65 Meg drive.) There are also a several other 20 Meg configurations (types 9?, 16?), one with 820 cyls. and 3 heads, and one with 612 heads instead of 615. If anyone is interested, I can post a list of about 40 of these, with their corresponding type #'s. -- Theodore A. Kaldis | "Perhaps we may +-+-+-+-+-+-+-+-+- | frighten away email: kaldis@topaz.rutgers.edu | the ghost of so UUCP: {...}!rutgers!topaz.rutgers.edu!kaldis | many years ago U.S. Snail: P.O. Box #1212, Woodbridge, NJ 07095 | with a little ex-Ma Bell: (201) 283-4855 (voice) | illumination . . ."
karl@ddsw1.MCS.COM (Karl Denninger) (08/16/89)
>Response 1 of 1 (4986) by kaldis at topaz.rutgers.edu on Tue 15 Aug 89 18:19 >[Theodore A. Kaldis] > >In article <216100121@trsvax> slimer@trsvax.UUCP writes: > >> I used to do this alot... let's see... I believe the problems could be >> the fact that a TYPE 2 does not represent a 20MEG drive. The drive TYPEs >> represent the number of cylinders and heads on the physical drive. > >Are you certain about this? I was under the impression that all >clones use the same numbers to designate drives. Type 2 is a 615 >cyl., 4 head, 17 sect. drive with 300 precomp. (the setting used for >for Seagate 225's). Type *6* is also a 20 meg with the same specs, >except no precomp. Argh! Seagate 225s prefer to be run with NO precomp, at least current run (drives <= 1 year old). I don't remember what the recommendation was two+ years back. Syquest drives, on the other hand, NEED precomp at cylinder 300 or they WILL lose their format over time. ST225s will function acceptably with precomp set at cyl 300, but that is NOT optimum. Use a NO precomp setting for your data's sake. With no precompensation set we have had ST225s exceed 4 years in the field (some of our first installs) without ANY trouble. In fact, the ST225 is a very reliable unit, providing it is installed properly and parked when the unit is moved. It doesn't seem to have the problems that some runs of the 251s have had. For those of you who don't think precomp is terribly important, you are wrong. Incorrect precompensation settings contribute to data loss over time, as the drive mis-aligns writes slightly as time goes on. Precomp is there for those drives which _need_ it in order to get the writes "on the money". If you don't need it, don't use it. If in doubt check the drive specifications from the manufacturer -- DO NOT GUESS unless you like reformatting your drive every six months or so. Also in that vein, if the manufacturer says the drive wants precompensation at cylinder 400, and the best you can do in the tables is cylinder 300, find a third-party driver that will let you set up correctly. As for clones and drive table layout there is no standard. There are similarities, especially in the first 15 types -- 'fer instance I don't recall ever seeing a clone where types 2 & 6 weren't the same except for the precomp, both being 615 X 4 X 17. But that certainly does NOT hold true for any of the other types in the table, and especially beyond type 15. -- Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl) Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910] Macro Computer Solutions, Inc. "Quality Solutions at a Fair Price"
ske@pkmab.se (Kristoffer Eriksson) (08/18/89)
In article <[24e8db3e:4986.2]comp.ibmpc;1@ddsw1.MCS.COM> karl@ddsw1.MCS.COM (Karl Denninger) writes: >Seagate 225s prefer to be run with NO precomp, at least current run (drives ><= 1 year old). I don't remember what the recommendation was two+ years >back. In the "Universal Installation Handbook" published by Seagate in 1987 the ST225 is listed with write precompensation from cylinder 300. -- Kristoffer Eriksson, Peridot Konsult AB, Hagagatan 6, S-703 40 Oerebro, Sweden Phone: +46 19-13 03 60 ! e-mail: ske@pkmab.se Fax: +46 19-11 51 03 ! or ...!{uunet,mcvax}!sunic.sunet.se!kullmar!pkmab!ske
barton@holston.UUCP (barton) (08/18/89)
In article <[24e8db3e:4986.2]comp.ibmpc;1@ddsw1.MCS.COM>, karl@ddsw1.MCS.COM (Karl Denninger) writes: > >Response 1 of 1 (4986) by kaldis at topaz.rutgers.edu on Tue 15 Aug 89 18:19 > >[Theodore A. Kaldis] > > > >In article <216100121@trsvax> slimer@trsvax.UUCP writes: > > > >I was under the impression that all > >clones use the same numbers to designate drives. > > As for clones and drive table layout there is no standard. This is true, the drivetypes are bios-dependent. So unless they all used the same bios, there will be differences. -- Barton A. Fisk | UUCP: {attctc,texbell,vector}!warble!holston!barton PO Box 1781 | (PSEUDO) DOMAIN: barton@holston.UUCP Lake Charles, La. 70602 | ---------------------------------------- 318-439-5984 | +++++ "Hal, open the pod bay doors" --- Dave
karl@ddsw1.MCS.COM (Karl Denninger) (08/19/89)
>----- >Response 3 of 4 (4986) by ske at pkmab.se on Fri 18 Aug 89 14:33 >[Kristoffer Eriksson] > >In article <[24e8db3e:4986.2]comp.ibmpc;1@ddsw1.MCS.COM> karl@ddsw1.MCS.COM >(Karl Denninger) writes: >>Seagate 225s prefer to be run with NO precomp, at least current run (drives >><= 1 year old). I don't remember what the recommendation was two+ years >>back. > >In the "Universal Installation Handbook" published by Seagate in 1987 the >ST225 is listed with write precompensation from cylinder 300. That was in 1987; I am nearly certain the current recommendation is to run with no precomp. Will check my charts Monday and post a followup. -- Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl) Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910] Macro Computer Solutions, Inc. "Quality Solutions at a Fair Price"