ReadyNAS OS 6.x release notes and btrfs releases

It would be interesting to know about what had changed with btrfs since btrfs is directly related to the kernel version, not the btrfs-tools.

I had done some benchmarking a few weeks ago (on a regular pc) comparing the kernel 3.11 and 3.13 and I got almost double the speed for disk access with 3.13. I also tested with encryption, md5 raid and btrfs raids.

Here is a copy of it fwiw:

All tests have large image file (53687091712 bytes) on ssd and rsync'ed to hdd
All file systems are mounted with default mount settings
System load is a =< 0.08 when starting
All system loads are checked via 'uptime' right after transfer

uptime && rsync --progress -av /root/file.img /mnt/<mounted_file_system> && uptime

System:
Intel 4th generation i7
24GB DDR3 RAM
6 Seagate 7200 RPM drives partitioned into 10 100GB sections for each file system type

FREENAS (9.2.2)
---------------
(source image file on SSD zfs partition)

 |---------------------> System load after rsync job
 |       |-------------> Average speed of transfer (bytes/sec)
 |       |           |-> file system type / configuration
X.XX - 225,130,588 - ZFS-raidz2


UBUNTU 14.04 (3.13 kernel)
--------------------------
(source file on lvm2 + btrfs SSD partition)

 |---------------------> System load after rsync job
 |       |-------------> Average speed of transfer (bytes/sec)
 |       |           |-> file system type / configuration
2.50 - 126,502,235 - btrfs (btrfs single)
1.98 - 128,315,887 - ext4 (ext4 single)
2.18 - 382,506,707 - btrf_array (btrfs array of 6 disks)
2.16 - 382,217,414 - btrfs_raid (btrfs raid 6 array of 6 disks)
2.65 - 371,627,675 - btrfs_luks_raid (btrfs raid 6 on 6 individually encrypted disks)
2.44 - 371,695,543 - mdraid6 (btrfs on mdraid 6 - no lvm)
6.67 - 184,724,942 - mdraid_crypt (btrfs on luks on mdraid6)
2.67 - 356,173,930 - ext4_mdraid  (ext4 on mdraid 6 - no lvm)
6.08 - 221,764,447 - ext4_raid_crypt (ext4 on luks on mdraid6)

Notes:
- No zfs tests since only fuse driver was available and had really poor performance
- Writes to single drives are very slow
- Writes to mdraid where a single luks volume is created on top on mdraid is slow and creates a high system load.
- It seems when 6 luks volumes are created, then btrfs_raid added on top of that is an ideal configuration

UBUNTU 13.10 (3.11.0-18 kernel)
-------------------------------
(source image file on ext4 SSD partition - no lvm2)

 |---------------------> System load after rsync job
 |       |-------------> Average speed of transfer (bytes/sec)
 |       |           |-> file system type / configuration
 3.68 - 121,616,410 - btrfs (btrfs single)
 1.69 -  83,569,876 - ext4 (ext4 single)
 1.26 -  74,419,467 - btrf_array (btrfs array of 6 disks)
 1.41 -  77,090,661 - btrfs_raid (btrfs raid 6 array of 6 disks)
37.40 - 124,723,915 - btrfs_luks_raid (btrfs raid 6 on 6 individually encrypted disks)
 1.31 -  64,886,580 - mdraid6 (btrfs on mdraid 6 - no lvm)
 7.04 -  74,009,159 - mdraid_crypt (btrfs on luks on mdraid6)
 1.43 -  49,831,689 - ext4_mdraid  (ext4 on mdraid 6 - no lvm)
 1.89 -  81,415,686 - ext4_raid_crypt (ext4 on luks on mdraid6)
 1.19 -  95,285,972 - (zfs native 0.6.1 raidz2 on 6 disks)