Btrfs, EXT4 & ZFS On A Solid-State Drive

[ioannis]

...and another thing. Both ZFS and Btrfs have lots of features that are not present in EXT4. Some of them, such as indexing and dynamic volume management, can degrade performance. So knowing what is enabled and what is not, is also important. Does ZFS have more such features enabled by default etc?

[ioannis]

Guys, thanks for your nice benchmarks on FSs, but you repeatedly ignore the CPU usage/system-load on such tests. There is a bottleneck here somewhere (Btrfs HDD vs SSD) which needs to be identified.

[molletts]

ext4 SSD tweaks?

Has anyone with an SSD tried using the RAID optimisation options in ext4 (also available in ext2/3) to tweak it for better SSD performance?

What I have in mind is that the underlying flash memory block size on an SSD could be considered to be analogous to the RAID stripe width in that modifying a smaller or non-aligned block of data results in a read-modify-write cycle. The '-E stripe-width=n' option to mke2fs tells the filesystem block allocator to place data so as to try to avoid read-modify-write cycles if possible (i.e. align it to the start of a block and fill an entire block wherever possible).

If it's possible to find out from an SSD manufacturer (or even by querying the drive?) the flash block size, it might be interesting to compare performance of a drive set up "any old how" with one containing a partition that is aligned to the start of a flash block bearing a filesystem created with the stripe width option. One would expect to see some difference in the write tests but not in the read tests.

[korpenkraxar]

Looks like BSD+ZFS got murdered to me.

[solca]

Does your kernels (or udev) detect your SSD disks as no rotational?

(cat /sys/class/block/sda/queue/rotational)

[Michael]

Why not compare with the native ZFS performance in (open)Solaris instead of *BSD?

OpenSolaris b134 wouldn't boot on the ThinkPad W510.

[wpoely86]

Why not compare with the native ZFS performance in (open)Solaris instead of *BSD?

[Michael]

Did you use the "ssd" mount option for btrfs?

No, it's no longer needed or used. Btrfs will auto-detect if it's an SSD and apply optimizations accordingly. You can check in the dmesg when mounting Btrfs on an SSD and you should automatically see a message about SSD optimizations.

[joffe]

ZFS can use a flash drive as a cache device or intent log device.

http://www.nerdblog.com/2010/03/zfs-nas-followup-ssd-is-amazing.html

http://blogs.sun.com/roch/entry/using_zfs_as_a_network

For anyone considering a NAS or other multi-disk build with ZFS it is an interesting option.

[ernstp]

Did you use the "ssd" mount option for btrfs?