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.* $Header: D:/ext2-os2/doc/RCS/USAGE.IM,v 1.2 1995/08/17 09:44:46 Willm Exp Willm $
.*

.*  Linux ext2 file system driver for OS/2 2.x and WARP - Allows OS/2 to     
.*  access your Linux ext2fs partitions as normal drive letters.
.*  OS/2 implementation : Copyright (C) 1995  Matthieu WILLM
.*
.*  This program is free software; you can redistribute it and/or modify
.*  it under the terms of the GNU General Public License as published by
.*  the Free Software Foundation; either version 2 of the License, or
.*  (at your option) any later version.
.*
.*  This program is distributed in the hope that it will be useful,
.*  but WITHOUT ANY WARRANTY; without even the implied warranty of
.*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.*  GNU General Public License for more details.
.*
.*  You should have received a copy of the GNU General Public License
.*  along with this program; if not, write to the Free Software
.*  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

.*******************************************************************************
.*** V - Usage instructions                                                  ***
.*******************************************************************************

.nameit symbol=titre_500 text='Usage instructions'
.nameit symbol=titre_510 text='Lazy writes considerations'
.nameit symbol=titre_520 text='Automatic check disk'
.nameit symbol=titre_530 text='Fatal ext2-os2 errors'
.nameit symbol=titre_540 text='Case sensitivity considerations'
.nameit symbol=titre_550 text='Debug version of ext2-os2'

:h1 id=500.&titre_500.
:p.
This chapter describes some imortant usage instructions.

:ol compact.
:li.:link reftype=hd refid=510.&titre_510.:elink.
:li.:link reftype=hd refid=520.&titre_520.:elink.
:li.:link reftype=hd refid=530.&titre_530.:elink.
:li.:link reftype=hd refid=540.&titre_540.:elink.
:li.:link reftype=hd refid=550.&titre_550.:elink.
:eol.

:h2 id=510.&titre_510.
:p.
This release uses only lazy writes : it means that data are not committed
to the disk immediately. 
:color fc=red bc=default.
YOU *MUST ALWAYS* SHUTDOWN YOUR SYSTEM PROPERLY
:color fc=default bc=default.
so that data can be written to disk. 
:color fc=red bc=default.
IF YOU DON'T FOLLOW THIS RULE, YOUR
EXT2FS PARTITION WILL BE PROBABLY DAMAGED, AND YOUR DATA LOST.
:color fc=default bc=default.

:p.
I included a :link reftype=fn refid=599.sync.exe:elink. utility that flushes the cache to disk if you need to be
sure that data are committed without shutting down the system. This :link reftype=fn refid=599.sync.exe:elink. 
utility is still primitive, so please use it only when no other activity 
is taking place on your partition.

:p.
If you use ex2fs formatted removable media
(floppy, ...) data should be commited to disk before the media is
removed. You MUST run :link reftype=fn refid=599.sync.exe:elink. BEFORE removing the media from its drive.

:p.
There is an automatic flush during system shutdown. At that time the removable
media (if you used one) MUST be present in the drive.

:nt.
You'll notice that the shutdown process is slightly longer : this is absolutely
normal.
:ent.

:fn id=599.
:p.
sync.exe does exactly what its Unix counterpart (sync) does : it commits
all buffered data to disks.
:p.
Invocation :
:xmp.
sync
:exmp.

:nt.
sync.exe is still very primitive. Please ensure that all removable media are in their drives, and that there is no
activity on the &EXT2FS. volumes when you invoke sync.exe.
:ent.
:efn.

:h2 id=520.&titre_520.
:p.
When ext2-os2 mounts an &EXT2FS. partition and when read writes are enabled,
it will set the mount count in the superblock to its maximum value in order
to force a disk check when Linux mounts the drive.

:h2 id=530.&titre_530.
:p.
ext2-os2 fatal errors can appear in several forms :
:ol compact.
:li.A system halt with a register dump : this is a fatal exception trapped by
the &OS2. kernel, due for example to a NULL pointer assignment. In this case the kernel debugger
or a system dump is needed to track down the problem.
:li.A system halt with a cryptic message or a message like "Ext2-fs panic". It's a system
halt initiated by ext2-os2 due to an unexpected error. 
:li.A beep can occur and you'll see a message like "Ext2-fs error ..." in the ext2-os2 output : 
An unrecoverable error occured and ext2-os2 blocked the calling thread, making the calling process unkillable.
This is less rough than a system halt, but the system is in a dangerous state. In such case the system should have
been halted but it's just to give a chance to run sync.exe and shut down the system properly.
:li.The whole system can freeze tightly : it is probably because an infinite loop was entered. Here also the kernel
debugger is the only solution.
:li. One or more app seem to be frozen : it is probably a deadlock.
:eol.


:p.
In either case, your &EXT2FS. partition is in great danger ; To
minimize the risk of data loss, please do the following &colon.
:ol compact.
:li.Write down the output of ext2-os2.exe if any
:li.Run sync.exe if possible.
:li.If possible, IMMEDIATELY shut down thesystem properly , don't do anything else on the partition.
:li.Reboot Linux and run e2fsck -fv 
:li.If you can reproduce the problem please send me a test case, as well as ext2-os2.exe's output.
:eol.

:h2 id=540.&titre_540.
:p.
ext2fs is a case sensitive file system ; ext2-os2 does case sensitive comparisions,
but even if &OS2. supports case sensitive file systems, all the apps that uppercase
or lowercase file names are broken. Some parts of &OS2. are also broken : for instance
the OS/2 loader will uppercase executable names. I plan to add a switch to make
ext2-os2 case retensive (aka like HPFS) ...

:h2 id=550.&titre_550.
:p.
To help tracking ext2-os2 bugs, I included a debug version of ext2-os2.ifs.
Using it ext2-os2.exe will become A LOT more verbose. To use them you just have to :
:ol compact.
:li.Copy ext2d.ifs where you installed ext2-os2 (normally in \os2\fs\ext2 on your boot drive)
:li.Replace the line IFS=<path>ext2-os2.ifs <parms> with IFS=<path>ext2d.ifs <parms> in your CONFIG.SYS
:li.Run ext2-os2.exe -trace > ext2-os2.out
:li.Try to reproduce a problem
:li.Type Ctrl+C  in ext2-os2.exe's window, and save ext2-os2.out in a safe place.
:li.Please e-mail me a short description of the problem, and the *SMALL* interesting part of ext2-os2.out
(NOT the whole file please : this would cost me a tremendous amount of money to download it). If I need the whole
file then we'll see how you can send it to me.
:eol.

:nt.
ext2-os2.exe's output should be redirected to any file (here ext2-os2.out) anywhere, BUT NOT TO A
FILE LOCATED ON AN EXT2FS PARTITION.
Otherwise this would result in an infinite loop between ext2d.ifs and ext2-os2.exe ...
:ent.

:nt.
Don't run ext2-os2.exe for a long time when using ext2d.ifs : its output can produce a HUGE file 
(several MB).
:ent.

:nt.
You'll notice a big performance hit when running ext2d.ifs : this is a normal behaviour, since
a lot of trace data are "pumped" from ext2d.ifs, and many more context switches are necessary.
:ent.

:nt.
Please don't run any time critical app while using ext2-os2.exe with the -trace option set.
:ent.

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