Can I use SSD (e.g. 512GiB) to be cache for my filesystem (e.g. 16TiB) ?
I'd like to avoid my disks on NAS to spin up every day, as when my computers rsync to it, only file sizes, timestamps are checks, plus few data is actually updated (so 512GiB could allow, for waking up harddrives much less often, only for "SSD->HDD" "flush").
Any ideas how to set it up?
Please give me hints of potential ambiguities in question.
(Of course given "HDDs backed" filesystem is example, it could be NFS of any other)
Currently two filesystems I might like to "cache with ssd" to avoid disks spin ups, are: EXT4 on LVM, and Btrfs.
Use case: I have computer at room, that serves as Linux NAS. During day other computers sync to it periodically, so it's disks are spinning, falling a sleep/quiet at night. Most of time, computers rsync only few changed files and check sizes and timestamps of others, as usually very little new data (