issue with VSAN SSD cache configuration.

Hi, vmware community,

There is a problem with my current VSAN cluster, my deployment are showed below:

6.4TB HHD and 2x200GB SSD with RAID 0 for cache,

The read speed is up to 1.2Gb/s which is fit the SSD's top speed,

but the write speed is just 200-250MB/s which is very low to SSD's top speed.

By another hand, when i use vMotion move VMs from one host to VSAN database, there will shows a error which is said 'ssd congestion'.

Due to the read speed is great and write speed is going down I guess this issue probably related to the host's raid configuration, do you have any suggestion for use wirte-back or wirte-through mode for SSD cache?

Thanks