SSD cache

Using SSD as cache for HDD I/O can obviously improve performance. Your hardware or software must enable or support this feature.

• SSD 1:5 HDD as cache, but NVMe as 1:12.
• Durable with Intel or Samsung SSD.
• RAID加速可測量標準是IOPS，即I/O per second. 測量這個就可以知道，目前用的硬體夠不夠我們剪輯用的I/O速度。

REF: https://zh.m.wikipedia.org/zh-tw/IOPS

I/O monitoring: iowait% of top

http://victor.csie.org/blog/archives/292

iowait includes disk I/O, memory I/O, and also affected by process numbers!!