Linked by Rahul on Sat 18th Oct 2008 11:29 UTC
Linux While Ext4 was originally merged in 2.6.19, it was marked as a development filesystem. It has been a long time coming but as planned, Ext4dev has been renamed to Ext4 in 2.6.28 to indicate its level of maturity and paving the way for production level deployments. Ext4 filesystem developer Ted Tso also endorsed Btrfs as a multi-vendor, next generation filesystem and along with the interest from Andrew Morton, Btrfs is planned to be merged before 2.6.29 is released. It will follow a similar development process to Ext4 and be initially marked as development only.
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RE[3]: relevant?
by Morph on Sat 18th Oct 2008 21:29 UTC in reply to "RE[2]: relevant?"
Morph
Member since:
2007-08-20

Unix/Linux filesystems historically, with the notable exception of Reiser4, have been quite resistant to fragmentation.

Why is that? Someone more knowledgeable than I could probably point to some specific aspects of unix filesystem design that reduce fragmentation. But it was an issue for the designers to consider when the fs was designed, and is still an issue for people working on new filesystems today. How well that issue is dealt with by particular operating systems or particular filesystems is a separate question. (FAT certainly was notoriously bad.)

Edited 2008-10-18 21:30 UTC

Reply Parent Score: 0

RE[4]: relevant?
by sbergman27 on Sun 19th Oct 2008 00:45 in reply to "RE[3]: relevant?"
sbergman27 Member since:
2005-07-24

Why is that?

I think it likely has to do with respective history. Unix started out on the server and evolved onto the desktop. DOS/Windows started out on the desktop and evolved to the server. Unix filesystems were designed in an environment where the machine was expected to run, run, run. Downtime was expensive and to a great extent unacceptable. Defragmenting the filesystem would have been downtime, and thus unacceptable. Current community culture reflects that tradition.

Windows culture tends to look more to resigning one's self to fragmentation (and viruses for that matter) and then running a tool (defragger, antivirus) to "fix" the problem. When NTFS was designed, Windows users were already used to the routine of regular defrags, and would likely do it whether the filesystem required it or not. So why make fragmentation avoidance a high priority?

Edited 2008-10-19 00:46 UTC

Reply Parent Score: 1

RE[5]: relevant?
by UltraZelda64 on Sun 19th Oct 2008 20:47 in reply to "RE[4]: relevant?"
UltraZelda64 Member since:
2006-12-05

When NTFS was designed, Windows users were already used to the routine of regular defrags, and would likely do it whether the filesystem required it or not. So why make fragmentation avoidance a high priority?

True... it's hard to break a habit of defragging all the time; it feels like something's "wrong" or you're missing something after coming from DOS-based Windows to XP in my experience. Still though, I found that I had to defragment every week, *still*, to keep the performance up. It doesn't slow down near as bad as Win9x, but it does get noticeable.

On Linux, I use XFS primarily due to its efficiency at dealing with large files and the fact that it includes an online defragmenter. Fragmentation does still happen, and I run xfs_fsr occasionally, but it only really effects performance when I'm doing something extreme like using BitTorrent to download large, several-hundred-megabyte (or larger) files.

Reply Parent Score: 2

RE[4]: relevant?
by _txf_ on Sun 19th Oct 2008 14:24 in reply to "RE[3]: relevant?"
_txf_ Member since:
2008-03-17

It has to do with the fact the unix filesystems tend to allocate files on either side of the middle of the volume and not immediately one after the other.

This means that there is space after each file for edits and the appended gets allocated with the file as opposed to a fragment in the next empty space.

either way this article explains far better than I:

http://geekblog.oneandoneis2.org/index.php/2006/08/17/why_doesn_t_l...

Reply Parent Score: 3