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An f2fs teardownAn f2fs teardownPosted Oct 14, 2012 18:38 UTC (Sun) by cmccabe (guest, #60281)In reply to: An f2fs teardown by Aissen Parent article: An f2fs teardown
> The thing I don't understand, is why work isn't
> done to make btrfs fit this use case. It already > has less write amplification than ext4 or xfs > due to it's COW nature (I think Arnd Bergmann > did some research on that).
It's not obvious that btrfs is the best choice for SSDs. Ted T'so posted some information on this earlier: http://lwn.net/Articles/470553/
There is currently some work going into btrfs to make it a better match for SSDs. That would probably make an interesting LWN article of its own. Also keep in mind that the type of SSD you see on a desktop is much different than what you see in a mobile phone. The firmware is much fancier and so an optimization for one may be a pessimization for the other.
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An f2fs teardown Posted Oct 15, 2012 8:18 UTC (Mon) by Aissen (subscriber, #59976) [Link]
In the link you point to (very interesting BTW), Ted says that btrfs will be at a disadvantage in "fsync()-happy workload"s. So it varies between workloads.
I didn't use the work "SSD", and that's because (as you said) it might refer to different things. I talked about eMMCs and SD cards, which are the target use case of f2fs, and used in mobile phones.
An f2fs teardown Posted Oct 17, 2012 14:26 UTC (Wed) by arnd (subscriber, #8866) [Link]
I believe btrfs has improved significantly in this area, but its design means that it won't be as good as f2fs on the media that f2fs optimizes for. The issue with b-tree updates that Ted mentions in the link is something that f2fs avoids by having another level of indirection that is not copy-on-write, and btrfs suffers more from fragmentation because it intentionally does not garbage-collect.
On a lot of flash devices, btrfs starts out significantly faster than ext4 after a fresh mkfs, but it's possible that btrfs performance degrades more as the file system fragments with aging. I don't have any data to back that up though.
An f2fs teardown Posted Nov 16, 2012 15:33 UTC (Fri) by oak (subscriber, #2786) [Link]
Nobody mentioned compression, but I think BTRFS can use e.g. LZO compression. What's the situation with that?
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