Weekly edition	Kernel	Security	Distributions	Contact Us	Search
Archives	Calendar	Subscribe	Write for LWN	LWN.net FAQ	Sponsors

Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian

Posted Apr 26, 2006 14:19 UTC (Wed) by apolinsky (subscriber, #19556)
Parent article: Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian Administration)

The one concern I've always had about journalled file systems is the backup. I remember reading years ago the Unix Backup and Recovery book by Preston. In it, dump was claimed to be the most reliable tool for backups. Dump will work on ext2 and ext3 file systems. I don't believe it is available for the rest of them. There are all sorts of utilities available for backups, but their basis is generally tar or cpio. When you need to restore a file or file system, you want to be absolutely sure that the backup is reliable. Generally tar and cpio are fine, but over time I have come to agree with Preston. Dump seems to be best. That's why I've tended to stick with ext3.

As an aside, can anyone suggest a way of converting a reiser partition to ext3, short of a copy from one file system to another?

Alan

(Log in to post comments)

Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian

Posted Apr 26, 2006 15:21 UTC (Wed) by Duncan (guest, #6647) [Link]

> [C]an anyone suggest a way of converting a reiser
> partition to ext3, short of a copy from one file
> system to another?

While it's theoretically possible, it's also theoretically extremely
difficult to do in a "safe" manner. Reiserfs' dynamic inode allocation
and tail writing makes a working implementation extremely difficult, as
an "in place" conversion implies there's known unallocated free space in
which to start writing the converted data, and reiserfs breaks enough
traditional rules in that regard that one would virtually have to be a
Namesys employee familiar not only with the reiserfs code, but with the
years of practical experience and knowledge of what /doesn't/ work, that
they've gathered.

It's not something that just anyone could do and get it right, IOW.
Basically, the most practical way to get such a thing would be to contract
with Namesys to create such a converter. I'm sure they'd be very happy to
develop such a converter application, given a commercial contract to do
so.

Of course, that would cost real money, likely a non-trivial amount of it.
Practically speaking, it's easier, cheaper, faster, and more reliable, to
just buy another hard drive if necessary, and go the copy route.

Duncan

Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian

Posted Apr 26, 2006 17:22 UTC (Wed) by remijnj (subscriber, #5838) [Link]

Basically, the most practical way to get such a thing would be to contract with Namesys to create such a converter. I'm sure they'd be very happy to develop such a converter application, given a commercial contract to do so.

I'm not so sure they would be happy about this because they would be creating a tool so people can move away from reiserfs to ext3. Wouldn't that freak them out. Then again, money can buy lots of things.

But i agree that buying a disk is easier/better.

But maybe there is a way to do this, if both filesystems have a resize tool which can make partitions bigger and smaller you could do the following:

resize the reiser partition to just fit the data
create a new ext3 partition after it.
copy enough files to fill the ext3 partition
resize the reiser partition (smaller)
resize the ext3 partition (bigger)
goto 3

And when all is done you remove the reiser partition.

This is probably not possible with the existing tools because you would also have to move the ext3 partition forward on the disk to make this work. But i don't know the state of these tools nowadays.

filesystem backups

Posted Apr 26, 2006 17:46 UTC (Wed) by rfunk (subscriber, #4054) [Link]

XFS has xfsdump. Unfortunately with different syntax than dump.

I've come to the conclusion that rsync snapshots to an offsite disk are the best form of backup these days, at least for my purposes.

Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian

Posted Apr 26, 2006 18:01 UTC (Wed) by jeffs (subscriber, #4024) [Link]

> As an aside, can anyone suggest a way of converting a reiser partition
> to ext3, short of a copy from one file system to another?

There is a convertfs utility that will do an inplace conversion between
file systems. I have used it in the past with no problems. YMMV

http://tzukanov.narod.ru/convertfs/

jeff