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- Newsgroups: comp.sys.ibm.pc.hardware
- Path: sparky!uunet!think.com!linus!alliant!mydual!olson
- From: olson@mydual.uucp (Kirtland H. Olson)
- Subject: Re: Drive parameters needed for Seagate st251
- Message-ID: <1992Nov10.211303.29486@mydual.uucp>
- Reply-To: olson%mydual.uucp@alliant.com
- Organization: The Harvard Group, 01451-0667
- References: <1992Nov9.141507.19161@samba.oit.unc.edu>
- Date: Tue, 10 Nov 1992 21:13:03 GMT
- Lines: 51
-
- In article <1992Nov9.141507.19161@samba.oit.unc.edu> Mary.Evans@launchpad.unc.edu (Mary Evans) writes:
- >
- >I low-level formatted an st-251 using 820 cyl, 6 heads. I used debug to
- >do it. When I finished, the drive capacity showed anout 62 meg. Since
- >this is a forty meg drive, I'm puzzled.
-
- Sounds like the controller is an RLL type, so it used 26 Sectors Per
- Track instead of 17.
-
- >What is the relative danger in using the
- >drive formatted like this?
-
- Very dangerous unless you do backups daily. (Unless the drive *is* a
- 251R certified for RLL, in which case it's 4 heads and 26 spt.) Lots
- of folk do run RLL on MFM-certified drives, but there is real danger
- of losing data without warning.
-
- >Also, it (the low level) defaulted to 4, and I
- >changed it to one. I'v been advised that the XT probably should not have
- >a 1 to 1 interleave, so I'm gonna re-do that.
-
- Standard interleave for XT's is 6! That usually reduces the drive
- performance and you can do better. If you can run Spinrite II on it,
- you can optimize the interleave easily. The better performance will be
- at a lower interleave than 6, but 1 is unlikely.
-
- >
- >What is the actual drive geometry?
-
- ST 251, 251-1 820 cyl 6 hd 17 spt 821 rwc 821 wpc
- ST 251R 820 cyl 4 hd 26 spt 821 rwc 821 wpc
-
- The 251 & 251R are 40 ms access, the 251-1 is 28 ms
-
- All these drives are 40 meg types.
-
- Looks like you should replace either the controller or the drive so they
- match.
-
- Odd that we should encounter the same problem, I grabbed a controller
- from the scrap box the other day and it also was an RLL. But I noticed
- that Disk Manager kept offering me drives with "R" following the number
- and wised up.
-
- Hope this helps.
-
- --Kirt
-
-
- --
- Kirtland H. Olson olson%mydual.uucp@alliant.com
-