[comp.unix.microport] Floppy formatting and using

mem@zinn.MV.COM (Mark E. Mallett) (01/16/89)

I'm having the dangdest time using floppies on my Microport Sys V/AT
system (v 2.4).  When I first installed the thing, v 2.2, I did floppy
backups frequently without incident.  Now, I'll format a floppy
(/etc/format /dev/rdsk/fd096), and 9 times out of 10, I'll get write
errors trying to use it.  Subsequent attempts to write to the disk
(without reformatting) fail in the same place.  If I am persistent, I
can repeat a cycle of formatting and attempting to use the disk, and
eventually it will work.  (I have no such problems when I boot MS/DOS
and format/access disks.)  Needless to say, this makes multi-disk
backups very difficult.

Before I try scrounging another drive, can someone tell me if I am
running into a known Microport problem?

-mm-
-- 
Mark E. Mallett  Zinn Computer Co/ PO Box 4188/ Manchester NH/ 03103 
Bus. Phone: 603 645 5069    Home: 603 424 8129     BIX: mmallett
uucp: mem@zinn.MV.COM  (  ...{decvax|elrond|harvard}!zinn!mem   )
Northern MA and Southern NH consultants:  Ask me about MV.COM

mike@cimcor.mn.org (Michael Grenier) (01/18/89)

From article <435@zinn.MV.COM>, by mem@zinn.MV.COM (Mark E. Mallett):
> I'm having the dangdest time using floppies on my Microport Sys V/AT
> system (v 2.4).  When I first installed the thing, v 2.2, I did floppy
> backups frequently without incident.  Now, I'll format a floppy
> (/etc/format /dev/rdsk/fd096), and 9 times out of 10, I'll get write
> errors trying to use it.  Subsequent attempts to write to the disk

I had the same problem (though not 9 out 10 times) making multivolume
backups nearly impossible. One possible problem seems to be doing the 
formatting when lot of other things are going on like serial interrupts.

Anyway, I grew tired of the problem and wrote a floppy handler which
works off the end of a pipe, .i.e  ls|cpio -ocv|dbundle /dev/rdsk/fd ...

The code is based on W. Davidson's posting of bundle/unbundle which breaks
up the standard input across multiple volumes but my version will read
after write on every track and retry if it failed. It also formats the 
floppy automatically should it run into unrecoverable errors and prompt
for new diskettes at the end of each volume or to replace a diskette
that's being difficult.

It can be used with cpio , tar, or most anything.

If there is enough requests, I'll post otherwise by email.

    -Mike Grenier
     mike@cimcor.mn.org

raw@ushiva.UUCP (Roland Wilcher) (01/18/89)

In article <639@cimcor.mn.org> mike@cimcor.mn.org (Michael Grenier) writes:

>I had the same problem (though not 9 out 10 times) making multivolume
>backups nearly impossible. One possible problem seems to be doing the 
>formatting when lot of other things are going on like serial interrupts.
>
>Anyway, I grew tired of the problem and wrote a floppy handler which
>works off the end of a pipe, .i.e  ls|cpio -ocv|dbundle /dev/rdsk/fd ...

I also have this problem. Every time I have had this problem, when i
reformat the disk using ms-dos, the dos format program always reports 
a few K in bad sectors. In order to do backups I have had to format 
the disks under ms-dos and only use those with no bad sectors.
Looks like the uport stuff can't deal with bad sectors on the floppy.
Also appears that the uport format program does not detect the bad 
sectors either.
comments ?

---
Every absurdity has a champion to defend it.         raw@neologic%hal.crwu.edu
                                                {hal,decvax}!ncoast!ushiva!raw
                                                             Roland A. Wilcher
------------------------------------------------------------------------------

learn@igloo.UUCP (william vajk) (01/18/89)

In article <43@ushiva.UUCP>, raw@ushiva.UUCP (Roland Wilcher) writes:

> Looks like the uport stuff can't deal with bad sectors on the floppy.
> Also appears that the uport format program does not detect the bad 
> sectors either.
> comments ?

If one follows the instructions included with runtime, one does a
format, a labelit, and an mkfs. None of these added features are
needed to make a cpio backup, and result in a LOT of wasted time.

Running the other two does, somewhere in the sequence (I can't recall
where cause I stopped doing it) identify a read or write error. Hell,
they could have at least included a bell. On the other hand, they
could have done it right.


Bill Vajk                     | A person of quality is never intimidated.
learn@igloo                   | 

ken@uport.UUCP (Ken Chapin) (01/19/89)

In article <43@ushiva.UUCP> raw@ushiva.UUCP (Roland Wilcher) writes:
>I also have this problem. Every time I have had this problem, when i
>reformat the disk using ms-dos, the dos format program always reports 
>a few K in bad sectors. In order to do backups I have had to format 
>the disks under ms-dos and only use those with no bad sectors.
>Looks like the uport stuff can't deal with bad sectors on the floppy.
>Also appears that the uport format program does not detect the bad 
>sectors either.
>comments ?
>

A disk is no good if it has surface flaws in it. Also the format code does not
report errors (except for ocassional write errors) or try to do any mapping 
scheme with bad sectors.

Ken Chapin         UUCP: ...!{sun | ucbvax | ihnp4}!amdcad!uport!ken
Microport Systems
Technical Support         

nvk@ddsw1.MCS.COM (Norman Kohn) (01/22/89)

In article <1419@igloo.UUCP> learn@igloo.UUCP (william vajk) writes:
>In article <43@ushiva.UUCP>, raw@ushiva.UUCP (Roland Wilcher) writes:
>
>> Looks like the uport stuff can't deal with bad sectors on the floppy.
>> Also appears that the uport format program does not detect the bad 
>> sectors either.
>> comments ?
>
>If one follows the instructions included with runtime, one does a
>format, a labelit, and an mkfs. None of these added features are
>needed to make a cpio backup, and result in a LOT of wasted time.
>
Format will do just that; labelit won't look for bad sectors either.
The best simple way to scan for bad sectores is to use dd to copy
the volume to /dev/null. That way you don't even need to put a filesystem
on it.

Don't forget the bug (at least in uport 286) that causes silent errors
in the first format after boot.  If you reboot often, try reformatting
the disk rather then assuming it's bad.  If you seem to have a lot of
bad floppies, suspect your floppy drive. For some reason some drives
don't work happily with uport, and a simple drive swap may make quite
a difference.  (I've had to do it more than once.)


-- 
Norman Kohn   (...ddsw1!nvk!norman)
eves: 373-0564
days/ans svc: 650-6840

mem@zinn.MV.COM (Mark E. Mallett) (01/22/89)

In article <43@ushiva.UUCP> raw@ushiva.UUCP (Roland Wilcher) writes:
%In article <639@cimcor.mn.org> mike@cimcor.mn.org (Michael Grenier) writes:
%
%%I had the same problem (though not 9 out 10 times) making multivolume
%%backups nearly impossible.
%
%I also have this problem. Every time I have had this problem, when i
%reformat the disk using ms-dos, the dos format program always reports 
%a few K in bad sectors. In order to do backups I have had to format 
%the disks under ms-dos and only use those with no bad sectors.
%Looks like the uport stuff can't deal with bad sectors on the floppy.
%Also appears that the uport format program does not detect the bad 
%sectors either.
%comments ?

Are you suggesting that the Microport floppy problem is with bad
sectors?  Bad sectors on floppies are extremely rare.  I expect that
when I find a floppy with a bad sector, I need to find another
floppy.  Problems with floppies on my SYS V/AT system are extremely
common.  Even so, I specifically stated in my original posting (the
reference to which seems to have gotten lost here :-) ) that I could
format and use the floppies under MSDOS.  So that's not it, I'm afraid.

-mm-
-- 
Mark E. Mallett  Zinn Computer Co/ PO Box 4188/ Manchester NH/ 03103 
Bus. Phone: 603 645 5069    Home: 603 424 8129     BIX: mmallett
uucp: mem@zinn.MV.COM  (  ...{decvax|elrond|harvard}!zinn!mem   )
Northern MA and Southern NH consultants:  Ask me about MV.COM

wnp@dcs.UUCP (Wolf N. Paul) (01/22/89)

In article <439@zinn.MV.COM> mem@zinn.MV.COM (Mark E. Mallett) writes:
>Are you suggesting that the Microport floppy problem is with bad
>sectors?  Bad sectors on floppies are extremely rare.  I expect that
>when I find a floppy with a bad sector, I need to find another
>floppy.  Problems with floppies on my SYS V/AT system are extremely
>common.  Even so, I specifically stated in my original posting (the
>reference to which seems to have gotten lost here :-) ) that I could
>format and use the floppies under MSDOS.  So that's not it, I'm afraid.

That could still be it -- DOS will let you use floppies with bad sectors,
it simply marks them as unavailable in the FAT. If you get a floppy with
bad sectors, and format it under DOS, the format program will report,


	XXXXXXX bytes total
	   XXXX bytes in bad sectors
	XXXXXXX bytes available

whereas Uport's format program is a low-level formatting program, which neither
verifies the formatted floppy, nor records bad sector information (how should
it, since it doesn't know anything about a FAT, or a freelist.

Any bad sector handling would need to be built into MKFS, not format;
it may require changes to kernel file system code as well - don't know.
and floppies with bad sectors ARE unusable for things like tar or cpio
which look at the floppy as a stream of sectors -- can't have gaps in that.

The other alternative is to write a floppy archiver, which verifies each
floppy before writing to it, and keeps its own bad sector info somewhere
at the beginning of the floppy. It can then be made intelligent enough to
skip these bad sectors when reading or writing.
-- 
Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101
UUCP:     killer!dcs!wnp                 ESL: 62832882
DOMAIN:   dcs!wnp@killer.dallas.tx.us    TLX: 910-380-0585 EES PLANO UD

raw@ushiva.UUCP (Roland Wilcher) (01/23/89)

In article <439@zinn.MV.COM> mem@zinn.MV.COM (Mark E. Mallett) writes:
>
>Are you suggesting that the Microport floppy problem is with bad
>sectors?  Bad sectors on floppies are extremely rare.  I expect that
>when I find a floppy with a bad sector, I need to find another
>floppy.  Problems with floppies on my SYS V/AT system are extremely
>common.  Even so, I specifically stated in my original posting (the
>reference to which seems to have gotten lost here :-) ) that I could
>format and use the floppies under MSDOS.  So that's not it, I'm afraid.
>

I beg to differ. I too can reformat the floppies and use them under dos.
But dos marks bad sectors in the File allocation table on the floppy
Unix format has no equivalant mechanism. I have these problems on 
V/386 3.0e so it's not limited it seems to V/AT. I also had this same
foolishness on an AT&T 6386 running their System V 3.1 .






---
Every absurdity has a champion to defend it.         raw@neologic%hal.crwu.edu
                                                {hal,decvax}!ncoast!ushiva!raw
                                                             Roland A. Wilcher
------------------------------------------------------------------------------

mem@zinn.MV.COM (Mark E. Mallett) (01/25/89)

In article <45@ushiva.UUCP> raw@ushiva.UUCP (Roland Wilcher) writes:
>In article <439@zinn.MV.COM> mem@zinn.MV.COM (Mark E. Mallett) writes:
>>Even so, I specifically stated in my original posting (the
>>reference to which seems to have gotten lost here :-) ) that I could
>>format and use the floppies under MSDOS.  So that's not it, I'm afraid.
>>
>I beg to differ. I too can reformat the floppies and use them under dos.
>But dos marks bad sectors in the File allocation table on the floppy
>Unix format has no equivalant mechanism.

You are, of course, correct.  (Having written code to implement MSDOS
filesystems, you'd think I'd have taken that into consideration.)  But
I stand by the point that I was attempting to make, even if I did it
badly:  bad sectors in floppies are very rare.  I'd be very very
surprised if every single floppy disk that I have has bad spots, yet
that's what I'm told by trying to use them on my system.  And note
that reformatting them changes the location and sometimes the
existence of the bad sectors, which I also mentioned.  This is not the
behaviour of a bad disk; it is the behaviour of a bad disk drive,
interface, or software.

I use a number of different Unix systems often; my System V/AT system
is the only one with this trouble.  What I really wanted to know is
whether other people were having the same troubles, whether I should
try buying another drive.  Enough people have responded by saying their
System V/AT systems behave the same way, that I'm inclined to believe
it is indeed software.  Software people (me included) are always quick
to blame the hardware (or anything physical).  Here, though, I think
it's reasonable to question the software.

-mm-
-- 
Mark E. Mallett  Zinn Computer Co/ PO Box 4188/ Manchester NH/ 03103 
Bus. Phone: 603 645 5069    Home: 603 424 8129     BIX: mmallett
uucp: mem@zinn.MV.COM  (  ...{decvax|elrond|harvard}!zinn!mem   )
Northern MA and Southern NH consultants:  Ask me about MV.COM

brian@cbw1.UUCP (Brian Cuthie) (01/27/89)

In article <307@dcs.UUCP> wnp@dcs.UUCP (Wolf N. Paul) writes:
>... DOS will let you use floppies with bad sectors,
>it simply marks them as unavailable in the FAT. If you get a floppy with
>bad sectors, and format it under DOS, the format program will report,
>
>
>	XXXXXXX bytes total
>	   XXXX bytes in bad sectors
>	XXXXXXX bytes available
>
>whereas Uport's format program is a low-level formatting program, which neither
>verifies the formatted floppy, nor records bad sector information (how should
>it, since it doesn't know anything about a FAT, or a freelist.

Actually, there is a way for the uport driver and format routine to handle
bad sectors on floppies.  Instead of having 15 usable sectors per track, you
only use 14.  This leaves one sector per track for alternate mapping.

The disk controller (be it floppy or hard disk) does not care what order the
sectors are in.  Thus assume sectors were normally ordered (use 1:1
interleave for simplicity) 1 2 3 4 5 6* 7 8 9 10 11 12 13 14 XX.  If sector
6 were bad, then it could be remapped by the format program so that the
track was formated in this order: 1 2 3 4 5 XX 7 8 9 10 11 12 13 14 6.  The
controller would never know the difference, since it always searches for the
proper header id before reading/writing a sector.

-brian



-- 
Brian D. Cuthie                                 uunet!umbc3!cbw1!brian
Columbia, MD                                    brian@umbc3.umbc.edu

wnp@dcs.UUCP (Wolf N. Paul) (01/27/89)

In article <136@cbw1.UUCP> brian@cbw1.UMD.EDU (Brian Cuthie) writes:
>Actually, there is a way for the uport driver and format routine to handle
>bad sectors on floppies.  Instead of having 15 usable sectors per track, you
>only use 14.  This leaves one sector per track for alternate mapping.

But then people would complain about losing 80 KB per floppy, even if
there are no bad sectors on it.

I recently swapped my floppy with one I had in a DOS-only machine, and most
of my floppy problems went away. The drive which was giving me trouble
under UNIX works just fine under DOS, where timing is not as crucial.
-- 
Wolf N. Paul * 3387 Sam Rayburn Run * Carrollton TX 75007 * (214) 306-9101
UUCP:     killer!dcs!wnp                 ESL: 62832882
DOMAIN:   dcs!wnp@killer.dallas.tx.us    TLX: 910-380-0585 EES PLANO UD