dm_crypt: very low performance of random IO operations
I'm experirncing problems with performance of random IO operations of
Sequential IO is good (using AES-NI gives almost no difference comparing with
unencrypted device), but random IO is poor comparing with unencrypted devices.
For benchmarking i've used simple utility, that reading small pieces of data
from a raw disk device, in a random access pattern. The utility measures the
number of seeks per second (reading operations per second), the device can do.
The source code of utility is attached. Also avalilable via link
I've tested 2 RAID arrays:
1. RAID 10 of 4 x Intel X25-E SSD drives (/dev/sdb)
2. RAID 10 of 8 x Seagate Savvio 15K 2.5" SAS drives (/dv/sdc)
Both arrays is handled by Adaptec 5805Z RAID card.