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| Ext4 Completes Development Phase |
| By special contributor Rahul on 2008-10-18 11:29:47 |
| 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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| Defragmentation |
| By adkilla on 2008-10-18 16:22:36 |
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Is ext4 less prone to performance degradation on filesystems with less space for defragmentation? I've read that it improves this situation somewhat but no specifics thus far. |
 - Score: 1 |
| RE: Defragmentation |
| By NxStY on 2008-10-18 16:41:23 |
| Ext4 has some features to reduce fragmentation, delayed allocation for example. There will also eventually be an online defragmenter. |
| - Score: 7 |
| RE: Defragmentation |
| By segedunum on 2008-10-18 17:00:47 |
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No too sure what you mean, as ext3 had no official defragmentation tool (I'm assuming you're comparing ext4 to something). It kept fragmentation to a minimum by allocating blocks that were closest to a file, but inevitably, this compromised other things and you still got fragmentation over time. This was alright in fairly static partitions such as /, /usr etc. but killed partitions with lots of file activity over time. ext4 has online defragmentation and also support for extents, which filesystems like XFS have provided for some time. You can't break the laws of physics though. If you are going to defragment then you have to have enough free space to move all your files around, and if you don't then parts of your filesystem will simply stay fragmented with all the performance issues that entails. However, defragmentation is merely a necessary evil with today's storage technology and you can only do so much. If SSDs kick on over the next few years and we get the same random read and write access no matter where in a storage device a file block is allocated, then fragmentation issues will start to disappear. There are actually many ways you can defragment and order data with today's mechanical disks with respect to performance. It really depends on the type of data and usage, and that's what is so difficult. Any person who tells you that a modern filesystem can solve all that is well wide of the mark. |
| - Score: 1 |
| RE[2]: Defragmentation |
| By adkilla on 2008-10-18 17:01:32 |
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Doesn't ext3 already have an online defragmenter? I recall that the major drawback of it that it needs a significant amount of freespace to be effective. From wikipedia: http://en.wikipedia.org/wiki/Ext... "Ext4 will eventually also have an online defragmenter. Even with the various techniques used to avoid it, a long lived file system does tend to become fragmented over time. Ext4 will have a tool which can defragment individual files or entire file systems." |
| - Score: 1 |
| BTRFS, Reiser4 without the stigma? |
| By adkilla on 2008-10-18 17:09:25 |
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Seems like BTRFS is much more along the lines of a modern filesystem like ZFS or Reiser4. If BTRFS is to be merged in 2.6.29, would it be stable enough for desktop use then? Though not suitable for critical production use. |
| - Score: 1 |
| RE[2]: Defragmentation |
| By adkilla on 2008-10-18 17:11:06 |
| Yeah, but the question is how much of space? Ext3 currently needs a 30% space requirement to reduce the effects of fragmentation. |
| - Score: 1 |
| RE: BTRFS, Reiser4 without the stigma? |
| By kragil on 2008-10-18 17:39:17 |
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It won't be ready for the desktop. It is still in development. Oracle, Red Hat, IBM and Novell want something that has even more features than ZFS (when combined with a logical volume manager). But it will take until 2010 until you will see it in production. Maybe the next RHEL will ship it. That is just a guess though. |
| - Score: 2 |
| RE[3]: Defragmentation |
| By segedunum on 2008-10-18 17:55:31 |
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> Yeah, but the question is how much of space? It depends on how big your files are. If you have 10GB free space and a 15GB file somewhere then you're going to struggle. |
| - Score: 1 |
| RE[3]: Defragmentation |
| By segedunum on 2008-10-18 17:56:46 |
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> Doesn't ext3 already have an online defragmenter? No. > I recall that the major drawback of it that it needs a significant amount of freespace to be effective. All defragmenters need free space, and how much depends a lot on the size of your files. |
| - Score: 1 |
| RE[2]: BTRFS, Reiser4 without the stigma? |
| By c0t0d0s0 on 2008-10-18 18:11:15 |
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Hmm .... i don't think you will see brtfs in 2010 in real production. The development of a totally new filesystem is a longer process. Just think about the time ext needed to get production ready. Or the fact that reiserfs is still suspected to loose files when loaded with millions of files. brtfs it's not like ext[1-4], which is a evolutionary development, it's something completely new. BTW: The whole brtfs development looks like a "Oh, heck, we need something similar to ZFS ...". I hope they make a better job with brtfs as with systemtap. And i do not believe that the ZFS development will stop ... in 2010 ZFS will have more features, too. Edited 2008-10-18 18:11 UTC |
| - Score: 3 |
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