Mikulas, > If there is some particular SSD that has more write IOPS for 8k requests > than for 4k requests, I'd like to know about it - out of curiosity. SSD blocks are getting bigger and bigger, some drives hide it better than others. Also look at all the efforts going on wrt. supporting larger block sizes in the kernel. Can you send me the output of: # sg_vpd -p bl /dev/sdN and maybe hdparm -I too? I'd like to see if we can come up with a reasonable heuristic. -- Martin K. Petersen Oracle Linux Engineering