On 9/11/13 6:16 AM, Dirk Müller wrote:
Hi Matthias,
Besides Scalability there are other attributes where btrfs exceeds other filesystems.
Regarding the scalability part, lets not compare something from 3 years ago, lets compare the 13.1 kernel, kernel 3.11.0. Ext4 has had pretty nice improvements in 3.11 regarding scalability, see http://lkml.indiana.edu/hypermail/linux/kernel/1307.0/00286.html for details.
http://www.phoronix.com/scan.php?page=article&item=linux_311_filesystems
You might or not like this benchmark, but the headline is pretty clear: "EXT4 wins".
Also, did btrfs fix the backlink issue? that seems to be a major scalability burden actually.
Again, yes: commit f186373fef005cee948a4a39e6a14c2e5f517298 Author: Mark Fasheh <mfasheh@suse.de> Date: Wed Aug 8 11:32:27 2012 -0700 btrfs: extended inode refs This patch adds basic support for extended inode refs. This includes support for link and unlink of the refs, which basically gets us support for rename as well. Inode creation does not need changing - extended refs are only added after the ref array is full. Signed-off-by: Mark Fasheh <mfasheh@suse.de> The current issue is the ability to enable them online. I have patches to do that posted to the btrfs mailing list. -Jeff
And just to compare the _scalability_ we're talking about. the corner cases are:
BTRFS supports filesytems up to 16384 Petabytes. Ext4 has a slight disadvantage here, only spporting filesystems up to 1024 Petabytes. While that sounds like a serios scalability issue for SLE, it is less of a concern for the typical openSUSE case.
Other scalability marks are not that interesting. But if we care about scalability and SSD support, F2FS might be interesting to look at as well..
Greetings, Dirk
-- Jeff Mahoney SUSE Labs