I'm using Ubuntu 16.04.4 and it's running on a VM.
The disk that has the origin data has an I/O limit on 1MB/s and disk for cache has no limit.
I have followed the guide at fibervillage
to create the LVM and succeeded without errors, with the modification to cachemode
writeback, and I also did try
writethrough just to try.
When the LV is without cache I got the expected behavior with 1MB transfer rate, But when I added the cahepool to the origin LV I do not see any performance enhancement at all. But creating a LV on the same disk were the cache pool is I get way faster transfer rate. I mounted all volumes in
sync,dirsync options to avoid any other caching.