SSD caching

Speed up HDDs with additional SSD/NVMe caching.

Options:

• OpenZFS
  • it is possible to add cache and log devices to ZFS pool. Log is a journal for synchronous writes.
• LVM DM-Cache
  • it is possible to add cache device to logical volume: Improving read performance with dm-cache
  • It is hot-spot cache, to cache only frequently accessed data, so simple copy of big file doesn't fill cache.
  • Write cache is also possible: https://man.archlinux.org/man/lvmcache.7