Add support for true "Tiered storage" (bcachefs or similar)

[TheLinuxGuy]

Almost exactly a year ago, I made this feature request which got 19 people upvoting. 

 

Quote

Hybrid or "tiered" storage (NVME + SSD + HDD). Where "hot" data is in NVME, then transitions down the stack. Least used data is on hdd. In other words; a QNAP qtier alternative.

One possible solution for my feature request is to add "experimental" bcachefs support into unraid. Another option could be btrfs if they ever implement https://github.com/kdave/btrfs-progs/issues/610

 

bcachefs is available in mainline kernel 6.7...  given this plus the amount of interest about this in the unraid community, I feel that @limetechshould really consider working on this feature.

[JSE]

I would like to eventually see bcachefs pools be added to unraid someday, but it still misses a lot of functionality. Namely, the ability to easily monitor an array, scrub, rebalance when adding/removing devices, and a proper process for device replacement. Not to mention there have been several major data loss bugs since the 6.7 merge. The filesystem is still considered experimental for a reason. I would prefer we hold off until it has had time to mature and become a better, well rounded solution before it's considered for inclusion in unraid.

Especially given we already have ZFS which has Arc caching, which is much better than linux's native caching. 

Edited February 8 by JSE
derp

[TheLinuxGuy]

@JSE that's fair, I am not married to the idea of bcachefs.

 

There could be a similar caching solution achieved with lvmcache + dm-cache with btrfs under the hood too, this option should be much more stable and proven than bcachefs.