Utilizing LVM to Cache HDDs on SSDs for Efficient Bulk Storage

Since the inception of solid-state drives (SSDs), there has been a choice to make—either use SSDs for vastly superior speeds, especially with non-sequential read and writes (“random I/O”), or use legacy spinning rust hard disk drives (HDDs) for cheaper storage that’s a bit slow for sequential I/O and painfully slow for random I/O.

The idea of caching frequently used data on SSDs and storing the rest on HDDs is nothing new—solid-state hybrid drives (SSHDs) embodied this idea in hardware form, while filesystems like ZFS support using SSDs as L2ARC.

However, with the falling price of SSDs,