Forums: Open Discussion (Thread #48742)

Does Disk Mark accurately measure random speeds for RAM Disks? (2023-03-05 06:43 by theorist #94424)

I have a 2019 i9 iMac with 128 GB DDR4-2666 RAM running MacOS Monterey. I created a 64 GB RAM disk and, using Disk Mark, found that the random writes (1 GiB, QD64 & QD1) were about 30 x faster on my 2 TB WD SN850 SSD (345 MB/s and 414 MB/s for QD64 & QD1) than my RAM Disk (13 MB/s for both). The QD 64 random reads were also faster (1711 vs. 638 for the SSD and RAM, respectively).

Results with a 10 GB RAM disk were similar. I'd post a screenshot, but that doesn't seem to be allowed here.

The sequential scores were, by contast (and as expected) about 3x faster on the the RAM Disk than the SSD.

Does this mean my RAM disk really is slower than my SSD for those operations, or is Disk Mark not properly configured to measure the performance of RAM disks on MacOS?