I have a 5 drive md array with dmcrypt on top, and btrfs on top of that.
Kernel: 4.4
Honestly, the performance is not good, but it's hard to pin down what
exactly is to blame (there could be performance issues with btrfs too).
I have read that dmcrypt is supposed to be multithreaded, and that's
been true for multiple years.
I put dmcrypt on top so that doing a raid sync or rebuild does not
involve encryption/decryption.
But can someone confirm that indeed if I have a single md device, and 4
CPUs, my throughput is not limited by a single CPU decrypting the
device?
And if I'm going to recreate the array (using bcache this time), is
there a better way to recreate it to avoid performance issues?
It is an array with many small files (filesystem backups), so lots of
random non contiguous I/O
Currently, I have:
gargamel:~# mdadm --detail /dev/md8
/dev/md8:
Version : 1.2
Creation Time : Sat Apr 19 23:03:59 2014
Raid Level : raid5
Array Size : 7813523456 (7451.56 GiB 8001.05 GB)
Used Dev Size : 1953380864 (1862.89 GiB 2000.26 GB)
Raid Devices : 5
Total Devices : 5
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Thu Feb 11 08:26:45 2016
State : active
Active Devices : 5
Working Devices : 5
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 256K
gargamel:~# cryptsetup luksDump /dev/md8
LUKS header information for /dev/md8
Version: 1
Cipher name: aes
Cipher mode: xts-plain64
Hash spec: sha1
Payload offset: 3072
MK bits: 256
Thanks,
Marc
--
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
.... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/ | PGP 1024R/763BE901
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