I need an opinion! (file system stuff)[SOLVED]

MattSmith · 2009-05-06 07:59:49

Hello fellow arch users! I have gotten rid of Windoze forever (hopefully), and not I need some help.

I want to migrate my file systems to ext4 even the /var partition which is now riserfs and get rid of the extended partition if possible. I believe that ext4 is now faster than riserfs with some files, if I'm wrong, someone please correct me.

right now my partition table looks like this:

Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xc3ffc3ff

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1       24957   200467071   83  Linux (left from windows now formatted to ext4)
/dev/sda3           24958       30401    43721408+   5  Extended 
/dev/sda5           24958       26174     9767488+  83  Linux (/ ext3)
/dev/sda6           26174       26843     5373711   83  Linux (/var riserfs)
/dev/sda7           26843       27390     4393746   82  Linux swap / Solaris
/dev/sda8           27390       30401    24186337   83  Linux (/home ext3)

and I would like it to look something more like

/dev/sda1 ext4 /
/dev/sda2 ext4 (or riserfs which ever is faster) /var
/dev/sda3 swap
/dev/sda4 ext4 /home

as you can guess I don't feel like loosing my information, and if possible avoiding a complete re-install.

I have thought about tar'ing up each partition to my external, and then whiping the hard drive, repartitioning the way i want, then unpack the tar's to the correct places, change the fstab to the correct things, but I dunno if that would even work. So I'm asking what would you do?

Last edited by MattSmith (2009-05-06 21:31:53)

fukawi2 · 2009-05-06 08:28:43

MattSmith wrote:

So I'm asking what would you do?

Backup /home /etc and /var/cache/pacman/pkg/ then format and reinstall.

MattSmith · 2009-05-06 08:43:25

Alright, I'll save that for a rainy day... since I leave in Seattle, it'll probably be tomorrow

/home /etc /etc and /var/cache/pacman/pkg/ will save my files, configuration, and what i downloaded, which means I am to reinstall everything correct?

Also, is it correct in asuming that ext4 has better performance that riserfs for small files? and if so should I just have 3 partitions instead of 4?

thanks for your help fukawi2

fukawi2 · 2009-05-06 11:53:46

MattSmith wrote:

/home /etc /etc and /var/cache/pacman/pkg/ will save my files, configuration, and what i downloaded, which means I am to reinstall everything correct?

Correct. It should cover everything, although some strange situations might mean something could be lost... Although if you've installed something that keeps it's config files in strange places not includes above, then you'd probably know about it anyway

MattSmith wrote:

Also, is it correct in asuming that ext4 has better performance that riserfs for small files? and if so should I just have 3 partitions instead of 4?

That's what I've heard, although I haven't really seen any benchmarks that dealt specifically with small files. There's also the issue with potential data loss after a power loss, but that has a work around if you're concerned about that. I'm running ext4 on a few partitions now and haven't had problems -- I have a UPS too though.

MattSmith wrote:

thanks for your help fukawi2

You're welcome

MattSmith · 2009-05-07 07:22:20

btw if anyone stuble upon this, and is worried about loss of data there really isn't much need to, epically if you have a laptop or a UPS, and a patch to fix it should be in the kernel by 2.6.30

here's the text of the wiki article:
Delayed allocation and potential data loss

Delayed allocation poses some additional risk of data loss in cases where the system crashes before all of the data has been written to the disk.

The typical scenario in which this might occur is a program replacing the contents of a file without forcing a write to the disk with fsync. Problems can arise if the system crashes before the actual write occurs. In this situation, users of ext3 have come to expect that the disk will hold either the old version or the new version of the file following the crash. However, the ext4 code in the Linux kernel version 2.6.28 will often clear the contents of the file before the crash, but never write the new version, thus losing the contents of the file entirely.

Many people find such a behavior unacceptable. A significant issue is that fixing the bug by using fsync more often could lead to severe performance penalties on ext3 filesystems mounted with the data=ordered flag (the default on most Linux distributions). Given that both file-systems will be in use for some time, this complicates matters enormously for end-user application developers. In response, Theodore Ts'o has written some patches for ext4 that cause it to limit its delayed allocation in these common cases. For a small cost in performance, this will significantly increase the chance that either version of the file will survive the crash.

The new patches are expected to become part of the mainline kernel 2.6.30. Various distributions may choose to backport them to 2.6.28 or 2.6.29, for instance Ubuntu made them part of the 2.6.28 kernel in version 9.04 -- Jaunty Jackalope.

yngwin · 2009-05-09 12:18:25

ext4 is still young, and problems (data loss) do occur. Of course, if you have a good backup strategy or don't care, playing with ext4 is just fine. Otherwise I would suggest using something more mature. If you want speed, then you should give Reiser4 a go, but this is unsupported on Arch (or any other major distro).

Arch Linux

#1 2009-05-06 07:59:49

I need an opinion! (file system stuff)[SOLVED]

#2 2009-05-06 08:28:43

Re: I need an opinion! (file system stuff)[SOLVED]

#3 2009-05-06 08:43:25

Re: I need an opinion! (file system stuff)[SOLVED]

#4 2009-05-06 11:53:46

Re: I need an opinion! (file system stuff)[SOLVED]

#5 2009-05-07 07:22:20

Re: I need an opinion! (file system stuff)[SOLVED]

#6 2009-05-09 12:18:25

Re: I need an opinion! (file system stuff)[SOLVED]

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