Two 100G s3700 drives, one tested with luks, one not.
Filled the drive to test with it filled.
Testing 4k/8k, with luks using --size=8 or --size=9 for 4k and 8k respectivly.
I used the following settings in fio, changing the filename and block size where appropriate.
[global] bs=4k ioengine=posixaio iodepth=32 size=200g filename=/dev/mapper/testssd direct=1 [rand-read] rw=randread stonewall [rand-write] rw=randwrite stonewall [seq-read] rw=read stonewall [seq-write] rw=write stonewall
There was generally high interupts and context switches, but oddly less so with luks.
- 4k sequential writes with luks was 73.7% of max ( 12424 vs 16855 )
- 4k sequential reads with luks was 76.7% of max ( 14471 vs 18864 )
- 8k sequential writes with luks was 71.0% of max ( 9640 vs 13573 )
- 8k sequential reads with luks was 71.8% of max ( 10744 vs 14966 )
- 4k random writes with luks was 82.2% of max ( 13919 vs 16924
- 4k random reads with luks was 80.7% of max ( 6260 vs 7756 )
- 8k random writes with luks was 71.7% of max ( 9718 vs 13557 )
- 8k random reads with luks was 64.7% of max ( 4222 vs 6526 )
My use case is zfs usage as l2arc/zil cache, I'll be using 8k on luks.