EXT2 / EXT3 / ReiserFS

[DigitAlex]

what are the big differences please ?

I mean on practical side, i don't really mind the theory behind it, i just wanna know what it can change actually ....

i seem to know that the 2 last ones are journalized, but that's all.

and another thing, is it possible to switch from one to another or do i have to install the distro again from scratch ?

thanks

 

[Nodsu]

Ext2 doesn't have journalling so it breaks easily.
Ext3 is basically ext2 plus a journal. Maybe a tad slower because of it.
ReiserFS is Something Completely Different. It performs better in extreme conditions (heavy load, thousands of files in a dir etc.)

You can switch between ext2 and ext3. I don't know if there is anything that can convert between ReiserFS.

If you want performance and to look cool, go for Reiser. If you are dual booting, you will not be able to access files on a Reiser partition from Windows.

If you want to play safe and have access to your Linux files from Windows, go for Ext. If you want to write to your Linux partition from Windows, you need Ext2.

From Linux point of view, you have a choice between Ext3 and reiser.
From Windows point of view you have the writable and easily breaking Ext2 or the read-only Ext3.

 

[DigitAlex]

It's a pure debian box
very old PC
not lots of files
windows doenst have to access the linux box, but the contrary, so i don't think it will change anything
so from what i have read, ext3 would be a better choice since i already have installed on ext2 and can switch
by the way, how can i do that ?

 

[Phantasm66]

I usually use Ext2 on dual boot machines, and Ext3 for machines that only have Linux.

Ext3 does not work with PowerQuest drive image as well, which is annoying because I make extensive use of this product.

 

[DigitAlex]

what about ghost ? issues with ext3 ?

 

[Nodsu]

"tune2fs -j /dev/hdxy" Will add a journal to an existing ext2 filesystem.

You have to make sure your kernel supports ext3 before doing that tho. If the kernel is anything newer than 3 years then it probably supports it.

 

[DigitAlex]

2.4.18 so i guess it's ok

what is the real advantages of journalising ?

 

[Phantasm66]

You will be fine, Alex, so long as Ext3 is actually compiled into your kernel. That version of the kernel code supports it as far as I know, if you are using a distribution kernel then it probably came with it enabled.

having a journal will make it much less likely that your file system will become corrupted if your system crashes.

tune2fs is a very hard command - you should all read the man page for it.

 

[DigitAlex]

it's a custom kernel so I think i'll have to recompile it again to enable ext3

 

[Phantasm66]

well, if you still have the config file you used you could cat and grep that and see if you used ext3....

cat .config | grep -i ext3

if you recompile, see if ext2 is compiled into the kernel, or is a module. i think its in the kernel.

you could then convert your ext2 to ext3 using the tune2fs command that Nodsu has noted.

 

[Mictlantecuhtli]

Linux filesystems benchmarks, includes ext2, ext3 and ReiserFS

Namesys, the creator of ReiserFS

LinuxPlanet looks at ReiserFS

Each time a new kernel version is installed, a new version of Reiserfs is required. The data on disk is upward-compatible so you don't have to reformat each time, but the filesystem code changes slightly. It takes a certain amount of care to ensure that you don't try to put the wrong Reiserfs version with the wrong kernel, and there is a slight delay between the release of a new kernel and the release of the Reiserfs patch for that kernel.

None of this is especially difficult if you have previous experience building kernels. The process is quite similar to applying the Alan Cox kernel patches, or the international crypto patches. Nonetheless, it can be quite daunting for someone new to Linux. It's especially tricky to create a Reiserfs root partition, since this requires temporarily booting off a backup partition as well as copying and recopying the files from the root partition. One false step, and you can be left with an unbootable machine and be forced to reinstall Linux from scratch or get help from a guru. It's certainly not something a new user should try!

 

[DigitAlex]

Thanks Mic.

Phant, I didn't use ext3 support when compiling.

 

[Phantasm66]

[root]# more mykernel.conf | grep -i ext3
CONFIG_EXT3_FS=m
CONFIG_EXT3_FS_XATTR=y
CONFIG_EXT3_FS_POSIX_ACL=y
CONFIG_EXT3_FS_SECURITY=y


I guess its OK to have Ext3 as a module, then....

But see how Ext2 is always compiled directly into the kernel...

CONFIG_EXT2_FS=y
CONFIG_EXT2_FS_XATTR=y
CONFIG_EXT2_FS_POSIX_ACL=y
CONFIG_EXT2_FS_SECURITY=y


These were the defaults from Red Hat supplied kernel config files.


But there's no harm whatsoever in compiling Ext3 in as well so I guess you should if it lets you.

 

[Goalie]

iirc, Ghost doesn't have any trouble with ext3. Dunno about reiserfs, I vaguely recall having ghosted one of those in the past, but could be wrong.