What is the optimal chunk size for Optane drives with MDM? I’m setting up a mirror of two P5800X drives and I would like to leverage the best possible read / write performance for these drives. @wendell had shown in benchmarks that the SQLite performance of these drives is best in class. What settings would be best to get to there?
root@s76:~# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 nvme3n1[1] nvme2n1[0]
390579264 blocks super 1.2 [2/2] [UU]
[==>..................] resync = 11.8% (46403584/390579264) finish=27.8min speed=205728K/sec
bitmap: 3/3 pages [12KB], 65536KB chunk
md0 : active raid1 nvme0n1p2[0] nvme1n1p2[1]
1951856640 blocks super 1.2 [2/2] [UU]
bitmap: 0/15 pages [0KB], 65536KB chunk
md0 is two Samsung 980 Pros in RAID 1.
md1 is two Intel P5800X in RAID 1.
The chunk size of 65536KB seems VERY large for NAND and 3DXPoint drives? md0 was setup during the Debian install and I feel that doesn’t seem like a sensible default for this type of device.