How can I use the fio utility to check the speed of SSD drives that are already assembled in RAID1?

Question

linux

Hello! There are 3 SSDs of 240gb each, which are marked in this way: a piece of 20G is "cut off" from each disk, these pieces are assembled in RAID1 and an operating system is installed on them. The remaining space on each disk is divided into 4 parts, which are used as logs for CEPH. How can I measure the speed of an SSD in my case without risking data loss? It is pointless to create a file for these purposes, because. it will be created in the raid and, accordingly, it will be possible to test the speed of only the raid, and not the disks included in it. And I'm afraid to specify a whole disk for testing, because. data may be corrupted during writing.

Answer 1

fio - low-level test, focus will fail. During a write test, the data will naturally be overwritten.