Information about loopback FS?

Information about loopback FS?

Post by Mats Liljegre » Wed, 25 Jun 1997 04:00:00

I would like to do a loopback filesystem, where can I get information
about how to do this?



Information about loopback FS?

Post by Wayne D. Hoxsie J » Wed, 25 Jun 1997 04:00:00

On Tue, 24 Jun 1997 14:06:07 +0200, Mats Liljegren

>I would like to do a loopback filesystem, where can I get information
>about how to do this?


The CD-Writer how-to has some information on this (Writing ext2 FS to
CD) but it's really very simple.

First, create a file for your loopback (This will make a 10 meg file):

dd if=/dev/zero of=myloop bs=1048576 count=10

Now put a filesystem on it:

mke2fs myloop

now just mount it:

mount -t ext2 -o loop=/dev/loop1 myloop /mnt

Now just use it like you would any other filesystem.  You'll get a
couple of warnings with the above commands (like myloop not being a
regular block device), but it will work.

Wayne D. Hoxsie Jr.

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Information about loopback FS?

Post by Peeter Joo » Wed, 25 Jun 1997 04:00:00

> I would like to do a loopback filesystem, where can I get information
> about how to do this?

> /Mats

I think I found the information in the man page for mount.  I don't
recall, but you may have to enable a kernel compile option to do this.



1. Is loopback-based FS slower than normal FS?

        Is a filesystem based on the new loopback (not to be confused
with the loop back device related to TCP/IP networking) device of Linux
v2.0.0 slower, faster, or just the same as a "real" (i.e. on a real
partition on the HD) filesystem?

        I ask this because I got an idea for users using the UMSDOS
filesystem.  I'm thinking people use UMSDOS 'cause they don't want to
repartition their drives.  The price they pay for using UMSDOS is a
slower filesystem, and wasted disk space due to the way FAT stores data.

        I'm thinking, that UMSDOS users can mount a ext2fs formatted
loop-back based filesystem as thier /usr filesystem.  Would this offer
any advantages?  Assuming that using a loopback device is just as fast as
using a real partition, there would be a speed advantage.  Also, storage
efficiency may be increased; just make the size of loopback file a
multiple of cluster size.  

        Comments please .....

Arcadio Alivio Sincero, Jr.
Sophomore, Computer Science Major at the University of Maryland at College Park
Amateur competitive bodybuilder

"D.A.R.E. .... to keep cops off donuts."

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