If you do a read or write larger than one sector to /dev/rdisk, that request will be passed straight through. Those devices are closer to the physical disk than the buffered cache ones. dev/rdisk – “raw” in the BSD sense and force block-aligned I/O. dev/disk – buffered access, for kernel filesystem calls, broken in 4kb chunks. On MacOS you should always use /dev/rdisk device. FIO is a popular tool for measuring IOPS on a Linux servers.ĭo not make mistake of benchmarking (or using dd for eg.) /dev/disk device. In Ubuntu/Debian/RHEL land I’ve benchmarked device IO before and had good experience with FIO. On MacOS however, Blackmagic Disk Speed Test in Mac App Store did not inspire confidence in me (blac kmagic, cmon?), not did 11yrs old Xbench or jDiskMark beta (written in Java). On Windows I used hdtune for ages and was happy with it. :)Īfter fitting disks in enclosures, first issue I stumbled upon was a lack of disk benchmarking tool on MacOS.

The one with higher price had to be better. Sceptical that I am, I bought both and decided to do a test and prove her that she is wrong. Good lady at the counter suggested that instead of 15EUR one, I get 13EUR noname enclosure since “it was better”. I visited my local hardware store to get USB3 2.5″ HDD enclosure, being geek, I did my homework and decided to get noname enclosure for 15 EUR with semi rubber protection. I wanted to see how will SSD disk act in same conditions. 99% of them broke or started showing serious problems just after 1st year of usage (traveling with them with the notebook). I have a really BAD track record of broken non-ssd 2.5″ travelling external disks. The other day, I noticed two Kingston SSDNow V200 128GB SSD’s just sitting there doing nothing, so I decided to make them usable again. Over time and numerous hardware updates around the office, I collected a vast number of 2.5″ HDD’s in my “hardware junk” box.

Mac disk speed test terminal