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Subjectmk2efs could format disk ??? (wa Re: LS-120 Formatting?)
In <Pine.LNX.3.96.981220183505.1172A-100000@ps.cus.umist.ac.uk> Riley Williams (rhw@bigfoot.com) wrote:
RW> Hi there.

RW> ===8<=== Lots of unnecessary insults omitted ===>8===

>>>> Great. Now take 1.88Mb floppy (maked with xdfcopy) and explain
>>>> how to create standard 1.44Mb floppy with mkfs.ext2 :-))

>>> mke2fs /dev/fd0H1440

>> Yes, really ?

RW> Yep...

Try before claim such things. 1.88Mb format is NOT compatible with any
standard format on low level (there are 1K sectors to start with :-). So
mk2efs will hanghs exactly the same way as in my experiment. fdformat will
work of course.

>>>> Format under DOS will do this quite happily.

>>> Why bother with DOS ???

>>>> Or even simpler: take 1.44Mb floppy and make 720Kb floppy from
>>>> it (this is safe).

>>> mke2fs /dev/fd0D720

>> Are you sure ? What about 5" 720K disks ? A have few 5" 1440Kb
>> disks and 720Kb disks :-))

RW> 5" 720k disks can be had with /dev/fd?h720 without problem. 5" 1440k
RW> disks are not one of the standard formats supported by Linux...

I have 5" 1440k disks and I'm could mount them as /dev/fd1H1440 just fine.
mke2fs works with them just fine if I use /dev/fd1H1440 and does not work
when I refer them as /dev/fd1h1200 !!! BTW 5" 720k disks could be ACCESSED
with /dev/fd?h720 but NOT CREATED from 360k or 1.2M disks not via
fdformat /dev/fd?h720 nor with mke2fs /dev/fd?h720 !!! Both commands will
just hungs !

RW> Incidentally, my understanding as to why these work when using
RW> /dev/fd0 doesnae is because the suffixed versions over-ride the
RW> drive's own details and return their own...

Yes, suffixed version just says: "no, autodect will fail for this drive -- do
not try it". Suffixed version could not magically reformat drive (fdformat
could and here suffixed versions are helpful since autodetect will fail here :-)
but could just say to kernel: "no there are not 18 sectors for track but only 9".
Kernel will happily use only 9 first sectors then. Floppy will look like 720K
floppy afterwards but still there are will be 18 sectors for each track (9 of
them not used). This is not a case for 1.88Mb drive vs 1.44Mb drive (different
sector sizes) nor for 1.2Mb drive vs 360K drive (different number of tracks).

>>> I regularly do the latter, and have never had any problems with
>>> it...

>>>> Again format under DOS will do this just fine.

>>> Again, why bother with DOS ???

>> Since in DOS low-level format and filesystem creation is combined
>> in one program unlike Linux.

RW> True, but irrelevant...

VERY RELEVANT -- see below. DOS format could change format of media if needed.
mke2fs COULD NOT ! NEVER ! Interpretation of format for already formatted media
could be changed (sometimes successfull, sometimes not) but reformating will
NEVER occurs.

>>>> PS. May be you have specially modified mkfs.ext2 which could do
>>>> low-level format but standard mkfs.ext2 will do just it:
>>>> create ext2fs filesystem on low-level formatted driver.

>>> If I do, then RedHat have been supplying a patched version since
>>> at least RedHat 4.1 when I started with Linux - I've been doing
>>> the above since then...

>> I'm just checked with RedHat 5.1 :-))

RW> Please advise re your findings...

>>> For reference, from this system:

>> Q>> $ ls -lFG /dev/fd0*
>> Q>> brw-rw-r-- 1 root 2, 0 May 5 1998 /dev/fd0
>> Q>> brw-rw-r-- 1 root 2, 12 May 5 1998 /dev/fd0D360
>> Q>> brw-rw-r-- 1 root 2, 16 May 5 1998 /dev/fd0D720
>> Q>> brw-rw-r-- 1 root 2, 28 May 5 1998 /dev/fd0H1440
>> Q>> brw-rw-r-- 1 root 2, 12 May 5 1998 /dev/fd0H360
>> Q>> brw-rw-r-- 1 root 2, 16 May 5 1998 /dev/fd0H720
>> Q>> brw-rw-r-- 1 root 2, 4 May 5 1998 /dev/fd0d360
>> Q>> brw-rw-r-- 1 root 2, 8 May 5 1998 /dev/fd0h1200
>> Q>> brw-rw-r-- 1 root 2, 20 May 5 1998 /dev/fd0h360
>> Q>> brw-rw-r-- 1 root 2, 24 May 5 1998 /dev/fd0h720
>> Q>> $

>> Ok. Just tried to use your braindead "theory" :

RW> ===8<=== Lots more rubbish omitted, relevant lines retained ===>8===

>> [root@localhost /root]# fdformat /dev/fd1h1200
>> [root@localhost /root]# mke2fs /dev/fd1h360

>> RedHat 5.1, /dev/fd1 -- 5" floppy drive, more information available
>> by request.

>> Why mke2fs works just fine after fdformat /dev/fd1h360 but not
>> after fdformat /dev/fd1h1200 ?

RW> Probably because those two are NOT compatible with each other.

Yes. It was EXACTLY what I'm want: two DIFFERENT, INCOMPATIBLE formats but
for the same physical media ! This is needed as countersample for your
stupid theory about magic format while mke2fs ...

RW> Try using the compatible options, which have been working fine for me for
RW> OVER TWO YEARS...and if they're not working for you, then either
RW> you've patched the kernel to prevent them from doing so, somebody else
RW> has done so, or the relevant entries in /dev have the wrong mknod
RW> numbers attached to them...

Yes, I know. But this will not prove ANYTHING about initial claim !!! If there
are compatible options then reformating is not needed !

RW> For reference, your second line should refer to

Q>> /dev/fd1d360
Q>> ^

RW> As I understand it, /dev/fd1h360 refers to a drive formatted as SINGLE
RW> sided, 80 tracks, 9 sectors per track, but I have never found a drive
RW> where it could be used...

You are joking. Yet again:
-- cut --
[root@localhost /root]# fdformat /dev/fd1h360
Double-sided, 40 tracks, 9 sec/track. Total capacity 360 kB.
Formatting ... done
Verifying ... done
-- cut --
What's the difference between /dev/fd?h360 and /dev/fd?d360 ??? You are joking !
This is just mean: high-density floppy formatted for 360k and double-density
drive formatted for 360k !!! (Why the difference ? Oh. Long story. There are
difference in coercive force for different types of floppies :-)

Just standard 2.0.34 kernel from RedHat 5.1 (I'm use some 2.1.x kernel usually
but specially for testing I'm reboted with this old one :-)

Here was you point: mk2efs could format drive. This is HORRIBLE wrong. I am
have physical media (5" disk :-) which could be formatted by two different
incompatible low-level format versions: as h1200 and as h360 (d360 will work
as well -- just information will be kept safely on disk for less time :-).
If mk2efs could format media (this was your initial claim and start of
discussion) then this should not lead to any problems. This is not a case:
if disk is formatted as h360 (via fdformat) mke2fs works, if disk is formatted
as h1200 (via fdformat) then mke2fs hangs horrible. What this means ? Just one
thing: mke2fs will not format disk ! NEVER !




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