hdd + ssd

[krautus at kr916.org]

Hello I'm trying to understand why and how to add one or more SSD (as a cache drive / keeping xfs log)
to a traditional spinning xfs storage volume.
I mean: which data will go to the ssd ? Inodes and dentries will go to the ssd ?
Will the _read_ performance increase ?

In general I'm looking to increase (cache) the reading performance of folders with a lot of small files (emails),
for email servers.

Feel free to let me rtfm :)
I'd gladly study the documentation / articles / benchmarks but my google-fu isn't in best shape.

Thank you,
Mike