Originally posted by phoronix
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bcachefs on both SSD *and* HDD.
Since all filesystems mentioned, except for btrfs can't do raid, we can limit the tests to btrfs and bcachefs.
Now bcachefs knows the difference between SSD and HDD. It will migrate active files to SSD.
btrfs doesn't, so it will just trash it.
Now we can get back ext4 and xfs into the test by creating 2 raid one devices, and put *bcache* on top of that, before actually creating the filesystem.
So that's the setup I would love to see you make:
bcachefs on 2 SSD's and 2 HDD's with nr of meta and data on 2, data and metadata checksum on
btrfs on 2 SSD's and 2 HDD's. with nr of meta and data on 2, data and metadata checksum on
ext4 on bcache on raid one on 2 HDD's and raid one on 2 SSD's with all checksums on (my normal install, except for the checksums)
xfs with the same and all checksums on
Now rsync garbage to the filesystem (linux tree multiple times in different directories), until it certainly exceeds the size of the SSD's.
And then try to test whatever you like.
Now that would make some interesting benchmarks.
And you still need to realise that both btrfs and bcachefs have data checksums, so they know about *filedata* integrity, and they know which disk contains a correct copy.
Raid will never know unless you use raid6, as it doesn't checksum blocks to know which one is correct.
Now we go for statistics and count the number of times you had to reformat a partition, or reboot due to kernel locks with a filesystem that is called stable.
In data loss and kernel locks in my experience btrfs clearly is the winner.
Second is xfs, but I heard it's stable now. I haven't used it as much as btrfs though.
Reiser4 to me was also causing low system uptime due to the panics.
Ext4 has a low count of 0 on data loss for me. Still reboots due to kernel locks (ext4 bugs) were still there.
Now bcachefs has not even been tagged experimental because it is not even upstream. But when I read bcachefs.org , I recognize all that pain that btrfs brought upon us.
Anyway: the clearest feature winner about bcachefs vs btrfs is it's history as bcache: SSD's for fast data, HDD's for long term storage. But if I read it correctly, the SSD is not used as a block cache anymore but as a file cache.
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