ir1@sdcc6.ucsd.EDU (ir1) (01/12/88)
Sender:Nathaniel Beck, Dept. of Pol. Sci. I just installed (or had installed, I should say) a Seagate 255 40M hard drive in my 6300. I have another identical machine with a 20M Seagate 225(?). The 255 is supposed to be faster than the 225, but it times out exactly twice as slow (either with the Norton Utilities SI or with a stopwatch timing to load). I didn't do the low level format or anything so I assume I have whatever interleave Seagate recommends. Does anyone have any ideas as to why the disk is so slow? Any help would be appreciated. Thanks in advance. Neal Beck Dept. of Pol. Sci. UCSD email beck@ucsd or beckc@sdcsvax.ucsd.edu
wtm@neoucom.UUCP (Bill Mayhew) (01/13/88)
The data transfer rate of the Seagate 225 and the Seagate 251 is 500K bits/sec. Norton "SI C:" is probably going to rate both drives about the same. For the ST-225, the average seek time is about 85 mS. For the ST-251, it is about 35 mS. Programs such as CORETEST or PC Lab's BENCH can analyze the seek time. The latter is available from PC Magazine. Picking an interleave factor is dependent on controller. With Seagate drives, and the DTC controller that comes the 6300, 3 or 4 seems to give the best performance for us. There is a program called LFORM on the PC6300 diagnostics disk that lets you do a low level format. It can be a study in hurry up and wait, but trying several interleaf factors is the only way to be sure. RLL drives can be even more mysterious. I have had to use anywhere from 1 to 7 on the PC6300. Controllers such as the SMS OMTI5627 give you tracks of 26 sectors, while the WD WX-A give you "virtual" tracks of 17 sectors as seen by the host, eventhough the drive itself has 26 sectors per track and fewer actual tracks. The WX-A gives really weird reports with CORETEST. Different applications programs and different versions of DOS will also react differently to various interleaf factors due to high level delays in buffering, etc. --Bill