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-
-
-
-UMSDOS HOW-TO
-
-
-
-----
-
-!!!UMSDOS HOW-TO
-
-!!Jacques Gelinas, jacques@solucorp.qc.cav1.2, 2001-12-01
-
-
-----
-'' ''Umsdos'' is a linux file system. It provide an alternative
-to the ''EXT2'' file-system. Its main goal is to achieve
-easier coexistence with ''Ms-DOS'' data by sharing the same
-partition.
-This document explain first how to use Umsdos in different
-configuration, and later explain its operation and try to
-provide some information letting you decide if it is
-a good choice for you (see UMSDOS-WHY-TO at the end).''
-----
-
-
-
-
-!!1. Copyright and License
-
-
-
-
-!!2. UMSDOS: Where is it ?
-
-
-****2.1 Copyright and License
-
-****2.2 History
-
-****2.3 Availability
-
-****2.4 Distribution supporting it
-
-****2.5 Home site
-
-****2.6 Technical documentation
-
-****2.7 Who wrote it
-
-
-
-
-
-!!3. Umsdos as your root partition
-
-
-****3.1 The pseudo-root concept.
-
-****3.2 Things to know about the pseudo-root
-
-
-
-
-
-!!4. Different topics about the operation of ''Umsdos''
-
-
-****4.1 Mount option
-
-****4.2 How to set defaults for the root
-
-****4.3 To swap or not to swap
-
-
-
-
-
-!!5. How to boot a Umsdos system
-
-
-****5.1 Loadlin
-
-****5.2 From a floppy
-
-****5.3 LILO
-
-****5.4 How to defragment a ''Umsdos'' partition
-
-****5.5 Advance tricks
-
-
-
-
-
-!!6. Basic principle
-
-
-****6.1 Introduction
-
-****6.2 ''Umsdos'' can replace the ''Ms-DOS'' file-system.
-
-****6.3 Directory promotion
-
-****6.4 How to promote: /sbin/umssync
-
-****6.5 Using /sbin/umssync at boot time
-
-****6.6 How to UN-promote
-
-****6.7 What about files created during a ''DOS'' session ?
-
-
-
-
-
-!!7. Installation/UN-installation and some tricks
-
-
-****7.1 The pseudo-root /mnt/linux
-
-****7.2 Preparing /mnt/linux
-
-****7.3 Making sure /mnt/linux is correctly setup
-
-****7.4 Oops releasing pseudo root ...
-
-****7.5 How to UN-install a ''Umsdos'' system
-
-****7.6 Moving a ''Umsdos'' system to another ''DOS'' drive
-
-****7.7 About installing 50 ''Umsdos'' systems.
-
-
-
-
-
-!!8. Setting a ''Linux'' section in a ''DOS'' partition
-
-
-
-
-!!9. UMSDOS-WHY-TO
-
-
-****9.1 The goal of ''Umsdos''
-
-****9.2 Who needs it
-
-****9.3 Performance issue
-
-----
-
-!!1. Copyright and License
-
-
-This document is Copyright (c) 1995 by Jacques Gelinas.
-
-
-It is released under the terms of the GNU Free Documentation License.
-A copy of the license should have been distributed with it, or you can
-see a copy at
-http://www.fsf.org/licenses/fdl.html.
-
-
-
-----
-
-!!2. UMSDOS: Where is it ?
-
-
-
-
-
-
-
-!!2.1 Copyright and License
-
-
-
-This document is Copyright (c) 1995, Jacques Gelinas.
-
-
-It may be distributed under the GNU Free Documentation License.
-You should have received a copy with it. If not, you can view it at
-http://www.fsf.org/licenses/fdl.html.
-
-
-
-
-!!2.2 History
-
-
-
-
-
-
-The ''Umsdos'' project was started in 1992 and made available
-to the net in January 1994 as a patch. It was included in the standard
-kernel distribution in July, starting with kernel 1.1.36.
-
-
-''Umsdos'' was early adopted in the ''Slackware'' distribution
-even before it was officially included in the official kernel.
-
-
-''Umsdos'' was improved starting at kernel 1.1.60. Its performance
-has been dramatically enhanced, especially for writing. Since 1.1.70
-(around this), it is stable again.
-
-
-A major bug was solve in ''Linux'' 1.2.2. This bug was causing
-some grief to users since the beginning (some file were
-silently renamed, giving the sad impression that they were
-deleted). Beware that ''Slackware'' 2.2 is still shipping
-release 1.2.1 of the kernel, so has this bug.
-
-
-
-
-!!2.3 Availability
-
-
-
-
-
-
-It is available as a patch for kernel 1..x. It is built-in
-for kernel 1.2. It can be compiled in or load as a module.
-Beware that for now, if you intend to load ''umsdos'' as a module,
-you must also use the Ms-DOS fs as a module. This come from
-a limitation in the module system (some symbols are only
-export when the drivers is installed as a module).
-
-
-
-
-!!2.4 Distribution supporting it
-
-
-
-
-
-
-So far, I think only ''Slackware'' does support it. I am surely
-wrong, so please send me info to correct this.
-
-
-
-
-!!2.5 Home site
-
-
-
-
-
-
-The home site for ''Umsdos'' is sunsite.unc.edu. Look in
-the directory /pub/Linux/system/Filesystems/umsdos.
-
-
-
-
-!!2.6 Technical documentation
-
-
-
-There is quite a lot of documentation about the internal of
-''Umsdos''. It is available both in HTML and text format
-at the same location as the utilities.
-
-
-As far as I know, the HTML version is not available online
-on any web site. You must down-load it and "UN-tar" it and
-read it locally.
-
-
-
-
-!!2.7 Who wrote it
-
-
-
-
-
-
-Jacques Gelinas jacques@solucorp.qc.ca
-
-
-
-----
-
-!!3. Umsdos as your root partition
-
-
-
-
-
-
-
-!!3.1 The pseudo-root concept.
-
-
-
-With ''Umsdos'', ''Linux'' can be installed in a standard
-DOS partition. ''Linux'' is then installed as a second (or
-third) OS in the partition. To avoid name collision (there
-is maybe a bin or tmp directory in the drive C: already),
-''Umsdos'' use
-a smart trick: The pseudo-root.
-
-
-All ''Linux'' files are installed in a DOS subdirectory
-called linux, generally C: LINUX. The normal
-''Linux/Unix'' directory structure goes there. So you
-get
-
-
-
-
-
-****
-
-C:\LINUX\BIN
-
-
-****
-
-****
-
-C:\LINUX\ETC
-
-
-****
-
-****
-
-C:\LINUX\LIB
-
-
-****
-
-****
-
-C:\LINUX\ROOT
-
-
-****
-
-****
-
-C:\LINUX\SBIN
-
-
-****
-
-****
-
-C:\LINUX\TMP
-
-
-****
-
-****
-
-C:\LINUX\USR
-
-
-****
-
-****
-
-C:\LINUX\VAR
-
-
-****
-
-
-
-When the ''Umsdos'' boot, it probes for the directory linux
-and then /linux/etc. If it exist, it activates
-the pseudo-root mode.
-
-
-Mostly, the pseudo-root mode switch the root of the partition
-to C:\\LINUX giving the conventional ''Unix'' directory
-layout
-
-
-
-
-
-****
-
-/bin
-
-
-****
-
-****
-
-/etc
-
-
-****
-
-****
-
-/lib
-
-
-****
-
-****
-
-/root
-
-
-****
-
-****
-
-/sbin
-
-
-****
-
-****
-
-/tmp
-
-
-****
-
-****
-
-/usr
-
-
-****
-
-****
-
-/var
-
-
-****
-
-
-
-To this list, it adds a new one called DOS. This one is
-a virtual directory.
-
-
-
-
-!!3.2 Things to know about the pseudo-root
-
-
-
-
-
-
-**** This mode can only be triggered
-at boot time. There is no way to activate this by
-a mount command.
-****
-
-**** This mechanism is purely a different view of a normal
-''Umsdos'' file-system. This means that a partition normally
-used as a root partition can be normally mounted. There won't
-be any pseudo-root effect.
-For example, if you boot linux with a maintenance floppy and
-mount your normal root partition in /mnt, you will
-find all your linux directory in
-/mnt/linux/bin, /mnt/linux/etc and so on.
-****
-
-
-
-
-
-
-
-
-
-
-----
-
-!!4. Different topics about the operation of ''Umsdos''
-
-
-
-
-
-
-
-!!4.1 Mount option
-
-
-
-
-
-
-You can use the same mount option as for the Ms-DOS file system.
-The option conv= is questionable on a ''Umsdos'' system. I suggest
-to avoid it. Mostly the option you may want to look at are
-
-
-
-
-
-****uid=
-****
-
-****gid=
-****
-
-****umask=
-****
-
-
-
-Just remember that ''Umsdos'' manage non promoted directory
-the same way as the ''Ms-DOS'' file system. The option above
-will apply globally to all non promoted directory. ''uid''
-setup the default owner, ''gid'' setup the default group
-and ''umask'' setup the default permissions.
-
-
-
-
-!!4.2 How to set defaults for the root
-
-
-
-
-
-
-umssetup was created to provide at run time default ownership
-for the root partition. For other ''Umsdos'' partition, mount
-option may be used or umssetup. Storing mount option in /etc/fstab
-is the prefered way for non root partition. Here is an example.
-Put this in /etc/rc.d/rc.S.
-
-
-
-
-
-/sbin/umssetup -u jack -g group -m 0755 /
-
-
-
-
-
-
-!!4.3 To swap or not to swap
-
-
-
-
-
-
-Using a swap file is generally slower than a swap partition.
-It is however much more flexible. You can setup a swap file
-in a ''Umsdos'' partition the same way you do it for any
-other ''Linux'' file systems. For example, to setup a
-8 megabytes swap file in the root directory:
-
-
-
-
-
-dd if=/dev/zero bs=1024k count=8 of=/swap
-mkswap /swap 8192
-sync
-swapon /swap
-
-
-
-
-Once done, you can put the following line in /etc/fstab
-
-
-
-
-
-/swap swap swap default
-
-
-
-
-And the swap file will be activated at each boot (There is
-generally a "swapon -a" in /etc/rc.d/rc.S).
-
-
-
-----
-
-!!5. How to boot a Umsdos system
-
-
-
-
-
-
-
-!!5.1 Loadlin
-
-
-
-
-
-
-The package lodlin15.tgz available from sunsite.unc.edu
-in /pub/Linux/system/Bootutils. This utility
-is particularly suited to boot a ''Umsdos'' system. Generally
-all you need to do is
-
-
-
-
-
-Boot DOS
-C:>loadlinx zimage root=D:
-
-
-
-
-where zimage is a normal kernel image (compressed) simply copied
-somewhere in the DOS drive. D: is the DOS drive where you
-have installed ''Linux''.
-
-
-
-
-!!5.2 From a floppy
-
-
-
-
-
-
-Booting a ''Umsdos'' system from a floppy is not different from
-booting a ''Ext2'' system. You need a kernel zImage file properly
-initialize to locate your root ''Umsdos'' partition. This
-is generally achieved using the command rdev. The following
-sequence will initialize a zImage and put it on a floppy.
-
-
-
-
-
-rdev zImage /dev/hda1
-rdev -R zImage
-dd if=zImage bs=8192 of=/dev/fd0
-
-
-
-
-If this looks confusing, just format a boot-able DOS floppy
-and put the following component on it.
-
-
-
-
-
-****loadlin.exe
-****
-
-****loadlinx.exe
-****
-
-****zimage
-****
-
-
-
-and setup the autoexec.bat like this
-
-
-
-
-
-loadlinx zimage rw root=C:
-
-
-
-
-
-
-!!5.3 LILO
-
-
-
-
-
-
-LILO, the official ''Linux'' boot loader can also be used
-to boot a ''Umsdos'' system. I have no experience with it
-though. Since 1.1.60, it should work. Please email if you know
-something.
-
-
-
-
-!!5.4 How to defragment a ''Umsdos'' partition
-
-
-
-
-
-
-It can be done using any popular DOS tool. There is nothing
-particular about file produced by ''Umsdos''. And ''Umsdos''
-do not expect anything particular (directory layout, directory
-entry sequence, etc...) from the file system under it.
-
-
-As far as I know, there is no ''Linux'' tool to achieve this.
-
-
-
-
-!!5.5 Advance tricks
-
-
-
-''Umsdos'' rely on the --linux-.--- which rely on the
-''DOS'' directory. Some users may want to experiment
-a bit. The utility udosctl part of the umsdos_progs
-package (containing umssync and umssetup) allows
-basic directory operation (listing, deletion) independently
-on the --linux-.--- and the ''DOS'' directory.
-
-
-
-
-
-
-----
-
-!!6. Basic principle
-
-
-
-
-
-
-
-!!6.1 Introduction
-
-
-
-
-
-
-''Umsdos'' map ''Linux'' files directly to ''Ms-DOS'' files.
-This is a one for one translation. File content is not manipulated
-at all. ''Umsdos'' only works on names. For special files (links
-and devices for example), it introduces special management.
-
-
-For each directory, there is a file named --linux-.---.
-
-
-
-
-!!6.2 ''Umsdos'' can replace the ''Ms-DOS'' file-system.
-
-
-
-
-
-
-''Umsdos'' can be thought as a general purpose superset
-of the ''Ms-DOS'' file system of linux. In fact this
-capability or flexibility yields much confusion about
-''Umsdos''. Here is why. Try to mount a newly formatted
-''DOS'' floppy like this.
-
-
-
-
-
-mount -t umsdos /dev/fd0 /mnt
-
-
-
-
-And do this,
-
-
-
-
-
-ls / >/mnt/LONGFILENAME
-ls -l /mnt
-
-
-
-
-You will get the following result
-
-
-
-
-
--rwxr-xr-x 1 root root 302 Apr 14 23:25 longfile
-
-
-
-
-So far, it seems that the ''Umsdos'' file system does not do
-much more (in fact nothing at all) than the normal ''Ms-DOS''
-file system of ''Linux''.
-
-
-''???''
-
-
-
-
-!!6.3 Directory promotion
-
-
-
-
-
-
-Pretty unimpressive so far. Here is the trick. Unless promoted
-a ''DOS'' directory will be managed the same way with ''Umsdos''
-than the ''Ms-DOS'' file-system will. ''Umsdos'' use a special
-file in each subdirectory to achieve the translation between
-the extended capabilities (long name, ownership, etc...) of
-''Umsdos'' and the limitation of the ''DOS'' file-system.
-This file is invisible to ''Umsdos'' users, but visible when
-you boot ''DOS''. To avoid cluttering the ''DOS'' partition
-with those file (--linux-.---) uselessly, the file is now
-optional. If absent, ''Umsdos'' behave like ''Ms-DOS''.
-
-
-When a directory is promoted, any subsequent operation will be
-done with the full semantic normally available to ''Unix'' and
-''Linux'' users. And all subdirectory created afterward will
-be silently promoted.
-
-
-This feature allows you to logically organize your ''DOS'' partition
-into ''DOS'' stuff and ''Linux'' stuff. It is important to
-understand that those --linux-.--- file do take some place
-(generally 2k per directory). ''DOS'' generally use large
-cluster (as big as 16k for a 500meg partition), so avoiding
-putting --linux-.--- everywhere can save your day.
-
-
-
-
-!!6.4 How to promote: /sbin/umssync
-
-
-
-
-
-
-A directory can be promoted any time using /sbin/umssync.
-It can be used at any time. Promoting a directory do the
-following operation
-
-
-
-
-
-****Create a --linux-.---.
-****
-
-****Establish a one to one relation between the --linux-.---
-and the current content of the directory.
-****
-
-
-
-/sbin/umssync maintain an existing --linux-.--- file.
-It does not create it from scratch all the time. It simply add
-missing entries in it (Files created during a ''DOS'' session).
-It will also removed files which do not exist anymore in the
-''DOS'' directory from the ''--linux-.---''. umssync gets
-its name from that. It put ''--linux-.---'' in sync with
-the underlying ''DOS'' directory.
-
-
-
-
-!!6.5 Using /sbin/umssync at boot time
-
-
-
-It is a good idea to place a call to /sbin/umssync
-at the end of your /etc/rc.d/rc.S if it's not there. The following
-command is adequate for most system:
-
-
-
-
-
-/sbin/umssync -r99 -c -i+ /
-
-
-
-
-The -c option prevent umssync from promoting
-directories. It will only update existing --linux-.---.
-
-
-This command is useful if you access ''Linux'' directory during
-a ''DOS'' session. ''Linux'' has no efficient way to tell that
-a directory has been modified by ''DOS'' so ''Umsdos'' can't
-do a ''umssync'' operation as needed.
-
-
-
-
-!!6.6 How to UN-promote
-
-
-
-
-
-
-Remove the --linux-.--- file using ''DOS''. You will
-be sorry.
-
-
-
-
-!!6.7 What about files created during a ''DOS'' session ?
-
-
-
-
-
-
-Unless you use umssync on a directory where files have
-been added or removed by ''DOS'', you will notice some problems:
-
-
-
-
-
-****It won't crash the system nor it won't cause major
-problems, only annoyance :-)
-****
-
-****Files created by ''DOS''.
-
-
-*****They will be invisible in ''Linux''.
-*****
-
-*****When trying to create a file with the same name,
-you will get an error message stating that the
-file already exist.
-*****
-
-*****This creates more confusion that real problem. It
-does not harm the file system.
-*****
-
-
-****
-
-****Files deleted by ''DOS'' won't cause problem. ''Umsdos''
-will notice the absence at the first access. A message
-will be output (and generally written into
-/var/adm/syslog).
-****
-
-
-
-
-----
-
-!!7. Installation/UN-installation and some tricks
-
-
-The installation of a ''Umsdos'' is not much different
-from the installation of an ordinary (''Ext2 based'') ''Linux''
-system.
-
-
-There are two main differences.
-
-
-
-
-!!7.1 The pseudo-root /mnt/linux
-
-
-
-The normal steps for an installation are
-
-
-
-
-
-***#Setting a partition with fdisk and formatting it.
-***#
-
-***#Mounting it as /mnt relative to our installation
-root disk.
-***#
-
-***#Copy all packages into /mnt.
-***#
-
-
-
-With ''Umsdos'', the step 1 is not required (wasn't it the goal
-of ''Umsdos'' not to reformat ?).
-
-
-It is possible to install a ''Umsdos'' system just by copying
-all packages into /mnt. This will certainly work. But it
-will create a
-bunch of subdirectories into your ''DOS'' root directory (C:) and
-you won't like it. This is the reason all ''Umsdos'' installation
-use the pseudo-root. And this is the major difference between
-a normal ''Ext2'' installation and a ''Umsdos'' one: All files
-are copied into /mnt/linux.
-
-
-
-
-!!7.2 Preparing /mnt/linux
-
-
-
-/mnt/linux is not an ordinary directory. It has to
-be promoted so it will correctly handle ''Linux'' long file name
-and special files (links, device). The step required to
-setup /mnt/linux are:
-
-
-
-
-
-***#mkdir /mnt/linux
-***#
-
-***#umssync /mnt/linux
-***#
-
-
-
-That's it!
-
-
-
-
-!!7.3 Making sure /mnt/linux is correctly setup
-
-
-
-Even if the setup of /mnt/linux is pretty simple, there
-are many installation package out there who get it wrong. How can ?
-
-
-The biggest installation problem come from an incompatible
-umssync program. ''Umsdos'' has been update in
-linux 1.1.88 (Can't remember exactly) and a flaw was uncovered
-in umssync. To avoid confusion in the ''Linux''
-community, it was decided to raise the compatibility
-level required for all ''Umsdos'' tools. Old version
-of the tools were simply rejected.
-
-
-It sounds like many distribution did not update their
-umssync utility on the installation disk.
-
-
-There are still many distribution like this out there. The net result
-is that the directory /mnt/linux is not promoted at all
-and will truncate all long file name and will reject all special
-file.
-
-
-It is possible to do a test very early during the installation to
-find out if something went wrong. Thanks to the pseudo console
-mechanism of ''Linux'', you can do that without leaving the
-installation program. Do the following steps:
-
-
-
-
-
-***#Press Alt-F2 (Alt key at the same time
-as the F2 key).
-***#
-
-***#login as root.
-***#
-
-***#cd /mnt/linux
-If this fail, you are trying this too early. A good time
-to do this is at the end of the packages selection.
-***#
-
-***#>TOTO
-***#
-
-***#ls -l
-You should see an empty file TOTO in uppercase. If you
-see it in lowercase, something went wrong. Try to do
-the umssync step again. umssync can be use over
-and over without problem.
-umssync .
-If there is no error message, try the TOTO test again.
-If
-TOTO appears fine, then all is OK. Something is strange
-in this installation, but you just save it. Continue
-
-***#
-
-***#Press Alt-F1 to get back to the installation screen.
-***#
-
-
-
-If the test fail, the best fix is to get a newer installation
-root disk. You can generally fix this root disk by installing
-a newer version of umssync. This is not difficult but
-required a working ''Linux'' system. You simply have to
-mount the root disk floppy and replace the offending
-umssync with a new one.
-
-
-
-
-!!7.4 Oops releasing pseudo root ...
-
-
-
-Most ''Umsdos'' installation which fail, do this by printing
-this strange message. This is not a bug in ''Umsdos'' although
-the message looks strange. Here are the known causes.
-
-
-
-
-
-****The most common one
-
-
-The ''Slackware'' installation try to setup a swap
-file very early during the installation. To do so, it asks
-you to select a partition (dos drive), then mount it and
-set the swap file.
-
-
-When installing a ''Slackware'' system, you must setup
-the target partition prior to install. This normally
-mounts the ''DOS'' partition on /mnt, creates
-the /mnt/linux directory and applies umssync
-on it.
-
-
-This is where most problems come from. Most user just
-forget the "setup target partition" step and go directly
-to the rest of the installation. Since /mnt is
-already mounted, this mistake goes unnotice.
-This means that /mnt/linux
-was not created properly (Not promoted). All special files
-and links and long names can't be created properly.
-
-
-
-
-****
-
-****Invalid umssync utility
-
-
-/mnt/linux was improperly setup-ed. Generally caused
-by an improper umssync utility on the installation
-root disk.
-
-****
-
-****Old bug in umsdos
-
-
-There was a bug in ''Umsdos'' prior to ''Linux 1.2.2''. The
-pseudo-root mode would not activate properly if the
-file /etc/init was missing. init is now located
-in /sbin. You can fix it by getting a newer kernel.
-This is recommended because another bug was uncover and fixed
-in 1.2.2.
-
-
-If you can't upgrade, do this
-
-
-
-
-
-****#Boot from you installation disk.
-****#
-
-****#Login as root.
-****#
-
-****#mount -t umsdos /dev/hdXX /mnt
-where /dev/hdXX is your ''DOS'' partition.
-****#
-
-****#cd /mnt/linux/etc
-****#
-
-****#ln -s ../sbin/init init
-****#
-
-****#cd /
-****#
-
-****#Ctrl-Alt-Del
-****#
-
-****#Boot your ''Umsdos'' normally.
-****#
-
-
-****
-
-
-
-Unfortunatly, the first two (Installation problems) produce a completly
-unusable installation. Uninstall it (See next section) and install
-again.
-
-
-
-
-
-
-
-!!7.5 How to UN-install a ''Umsdos'' system
-
-
-
-One neat thing about ''Umsdos'' and its pseudo-root
-mechanism, is that you can UN-install it without pain. You
-just boot ''DOS'' and recursively delete the linux
-directory. That's all. ''Umsdos'' requires no special
-drivers in the config.sys, nor it creates anything
-special outside of the linux directory.
-
-
-
-
-!!7.6 Moving a ''Umsdos'' system to another ''DOS'' drive
-
-
-
-This can be done from ''Linux'' or from ''DOS''.
-You just have to copy recursively the linux directory
-from one drive to the other. After that you will have to
-adjust you boot mechanism (generally loadlin command) and
-the /etc/fstab file.
-
-
-''Umsdos'' can live on any ''DOS'' drive. There is no
-need to install it on the C: drive, nor it is important
-to have it on the first hard drive. It does not matter at
-all.
-
-
-In fact, one may decide to have several ''Umsdos'' installations
-on different drive just to do experiments.
-
-
-
-
-!!7.7 About installing 50 ''Umsdos'' systems.
-
-
-
-How about installing a bunch of ''Linux'' systems in no time ?
-
-
-''Umsdos'' systems are living in a ''DOS'' world. You can
-take advantage of this if you wish to install ''Linux'' easily.
-
-
-You can install and configure a ''Umsdos'' system at your site.
-When you are satisfied with the configuration and the different
-packages you have selected, you can boot ''DOS'' and copy
-the complete linux directory to your ''DOS'' file
-server. Then you go to other ''DOS'' station and simply
-copy the files on the network drive to the local drive.
-That's it. Only adjust the boot script (''Loadlinx'') and go.
-
-
-With minimal adjustment (Host name, IP number), anyone will
-be able to install a ''Linux'' system in a matter of minute.
-
-
-Interest readers may note that installing ''Linux'' systems
-by copying running system also works for any other ''Linux''
-systems, including ''Ext2'' based one.
-
-
-One beauty of ''Linux'' is that there is no hidden files which
-have to be install by magic installation program.
-
-
-
-----
-
-!!8. Setting a ''Linux'' section in a ''DOS'' partition
-
-
-''Umsdos'' has some use even for ''Ext2'' (Native ''Linux''
-file-system) users. One common scenario is this:
-
-
-
-
-
-****''Linux'' being your ''OS'' of choice, the ''Linux''
-partition start to fill and fill and fill.
-****
-
-****Your ''DOS'' partition is collecting dust, being half empty.
-****
-
-****You are suddenly out of space in the ''Ext2'' partition.
-****
-
-****You are still not sure you want to get rid of ''DOS''.
-****
-
-
-
-''Umsdos'' may save the day
here. You can setup a ''Linux''
-directory in the ''DOS'' partition and use it without restriction
-for ''Linux'' usage. For example, say you want to setup a new
-directory named "extra" in your C: drive. And you want this
-directory to behave as a normal ''Linux'' directory. Do this
-(assuming that C: is /dev/hda1).
-
-
-
-
-
-mkdir /c
-/sbin/mount -t umsdos /dev/hda1 /c
-mkdir /c/extra
-umssync /c/extra
-
-
-
-
-You must be root to do this.
-
-
-By setting up /etc/fstab like this, you will always
-have access to the /c/extra directory.
-
-
-
-
-
-
-----
-
-!!9. UMSDOS-WHY-TO
-
-
-Explaining how to operate or install a ''Umsdos'' system
-is not enough. Most people are seeking some advises about
-using ''Umsdos'' or not.
-
-
-
-
-
-
-
-!!9.1 The goal of ''Umsdos''
-
-
-
-The goal of ''Umsdos'' was to ease the installation of
-''Linux''. An other goal was to ease its UN-installation.
-The idea here was to promote the spreading of ''Linux''.
-Installing a new OS on a system is always troublesome. ''OS/2''
-for one will happily pollute your C: root with a bunch of
-new directories. If you are clever like me, it will also erase
-your config.sys and autoexec.bat files :-(
-
-
-The pseudo-root feature of ''Umsdos'' avoid this unwanted
-invasion. ''Linux'' can be UN-install without side effect.
-
-
-
-
-!!9.2 Who needs it
-
-
-
-If you have a small hard drive, ''Umsdos'' will allow you
-to share disk space between ''DOS'' and ''Linux''. A disk
-below 300 megs is in my opinion a small disk. This opinion
-is based on the size of the different package available today.
-One popular word processor may eat as much as 70 megabytes
-if you select all features.
-
-
-If you have a larger drive, you may consider having a dedicated
-''Linux'' partition running the ''Ext2'' file-system. ''Ext2''
-use a smaller cluster size that ''DOS'' (1k in fact) so installing
-many small files will eat less space than in a ''Umsdos''
-partition.
-
-
-
-
-!!9.3 Performance issue
-
-
-
-The following point apply to ''Umsdos'' compared with ''Ext2''.
-
-
-
-
-
-****Directory management is faster on ''Ext2''. This come from
-the overhead of the double directory structure of
-''Umsdos''.
-****
-
-****File access (reading and writing) is probably faster on
-''Umsdos'' than ''Ext2''. This come from the simplicity
-of the ''FAT'' file-system used by ''DOS''.
-Beware that this simplicity come with a cost:
-
-
-*****A maximum of around 65,000 files or clusters
-per partitions. This also means that a 500
-megabytes partition will use cluster 16k large.
-In other word, a file containing a single byte
-will use 16k of disk storage.
-*****
-
-*****Everything is controlled by the FAT located
-at the beginning of the hard drive. The ''DOS''
-file-system is probably more fragile because of this.
-*****
-
-*****No provision to avoid fragmentation of files. A
-''Umsdos'' system will generally be used as
-a single user workstation. In this case, this does
-not matter much. As a multi-user engine, files
-will get spread-ed all around the drive, lowering
-file access performance.
-*****
-
-
-****
-
-****Symbolic links are stored in normal file. If you intend
-to have a lot of them, you will find that ''Umsdos''
-use quite a lot of disk space compared to ''Ext2''.
-****
-
-----
+Describe [HowToUMSDOSHOWTO]
here.
