ir1@sdcc6.ucsd.EDU (ir1) (01/15/88)
I am running an ATT6300 which for the purpose of this question is the same as an IBM XT. I was running a Seagate 225 20M hard disk which gave me a Norton Utility Index of 1.1. I have now switched to a 40M Seagate 251 with a WD WX1 controller, partioned into a small C, and a 20M D and E drive. (Partioning done with Speedstore.) The Norton Index on the 251 is .5, and stopwatch timings of program loading indicate that the new drive is half as fast as the old one. I didn't do the low level format and Seagate doesn't seem helpful (although they claim the 251 should be as fast as the 225). So, can any one help me out. I would happy if I got the 251 to be as fast as the 225, although happier if it were faster. Does anyone know the optimal interleave for the 251 with the WD WX1 and an XT. Alternatively is there a better half height drive for the money about $500-600). Thanks in advance Neal Beck Dept. of Pol. Sci beck@ucsd (Bitnet) beck@sdcsvax.ucsd.edu (Arpa)
davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (01/19/88)
In article <3579@sdcc6.ucsd.EDU> ir1@sdcc6.ucsd.edu.UUCP () writes: | So, can any one help me out. I would happy if I got the 251 to be as | fast as the 225, although happier if it were faster. Does anyone | know the optimal interleave for the 251 with the WD WX1 and an XT. There is no "best" interleave factor... with a very large interleaf factor (say 8) everything will run, but slowly. As you decrease the interleave things will get faster and then slower. The point at which this occurs depends on your wait states, disk controller, CPU speed, etc. It *also* depends on the program reading the data. A program which does read and process will run best with a fairly large interleave (say 4-8), while program loads by DOS (virtually no processing) will run blindingly fast at interleave 2. What you need to do is repeatedly do a low level format, high level format, and benchmark until you find out what works on your system. If you pick 6 for an XT and 4 for an AT you will be in a reasonable range, since these are the figures used by IBM. The optimal solution is to use a controller or disk cache program which does "track buffering." Since this allows the hardware to move the data, no interleave is needed, and all programs run very fast. We used to do this on large floppy systems when the PC was still a dream. The reason Seagate won't tell you what to use is that you have to find out for yourself, and determine if you want to trade program load for program run speed, and in which direction. It sounds as if your interleave is too small, but since you haven't checked it there's no way to tell. -- bill davidsen (wedu@ge-crd.arpa) {uunet | philabs | seismo}!steinmetz!crdos1!davidsen "Stupidity, like virtue, is its own reward" -me
howardl@wb3ffv.UUCP (Howard Leadmon ) (01/22/88)
In article <3579@sdcc6.ucsd.EDU>, ir1@sdcc6.ucsd.EDU (ir1) writes: > I am running an ATT6300 which for the purpose of this question is > the same as an IBM XT. I was running a Seagate 225 20M hard disk > which gave me a Norton Utility Index of 1.1. I have now switched to a 40M > Seagate 251 with a WD WX1 controller, partioned into a small C, > and a 20M D and E drive. (Partioning done with Speedstore.) The > Norton Index on the 251 is .5, and stopwatch timings of program > loading indicate that the new drive is half as fast as the old one. I didn't > do the low level format and Seagate doesn't seem helpful (although > they claim the 251 should be as fast as the 225). > Hello, First off let me point out that generally the best interleave is determined by the controller you are using, so you should look at the information you recieved with the HD Controller. Now let me tell you about my experiences with the various contorllers, and what we used with a ST-251. I installed a Seagate ST-251 in an IBM-PC the other day, and the contorller that came with the drive was a Western Digital WD1002-SWX series board (I think SWX). After several re-formats we decieded the best interleave was 4:1. This was tested using the CORE Harddrive test, and the throughput was about 130Kbytes per second. When using the recomended 3:1 interleave, throughput dropped to a mere 30Kbytes per second, and at 5:1 it was only down to 120Kbytes. This proves that too short an interleave really hurts!! Anyway the other Western Digital controllers I have worked with are the WD1003 and the WD1006 series. The best interleave with the 1003 is 3:1 and gives a throughput of about 190 Kbytes per second. The GREAT controller (and the one I use) is the WD1006 series, and it is a 1:1 interleave track-cache controller. The WD1006 will achive a throughput of nearly 400 Kbytes, and believe me you can tell when copying large files. Well I hope this is of interest to some of you net readers... Sincearly, Howard Leadmon Fast Computer Service, Inc. cp1!sarin!wb3ffv!howardl (301)-335-2206