[josefbacik]

Host managed also means messing with the file system, and the patch set for btrfs is not small. Plus you have to disable a bunch of features (like preallocation since you can’t move the write pointer backwards) which is going to surprise people in unfun ways. These drives are useless for general purpose. If you are going to use them as expensive tape then by all means, but otherwise I have serious doubts about their usefulnes.

Edit: I’m talking specifically about the SMR side. The general zoned stuff is interesting, but when you start putting restrictions on how you can write to certain zones you wind up with a lot of weirdness that application developers are going to be surprised by.

[amelius]

> If you are going to use them as expensive tape then by all means, but otherwise I have serious doubts about their usefulness.

Only writing is more complicated. Reading is still simple and fast; and random access reading is fast, unlike tape.

[rzzzt]

Drive-managed SMR looks OK to me for general use, although I don't have hands-on experience with it. They also have a non-shingled region that can accept random I/O at higher speeds, and the drive deals with moving data to a linear-only region once it fills up, or at garbage collection time.

It's very much like the QLC drives where a portion is treated as SLC/MLC.

[loeg]

It's like the QLC drives with SLC/MLC cache (e.g., Intel 660p) except the performance cliff is far, far worse (and obviously the "fast" mode is far worse as well).

[josefbacik]

Agreed, drive managed is far better from a usability standpoint.

[the8472]

Some of the fallocate modes don't make much sense on CoW filesystems anyway. ZoL doesn't support preallocation either, you have to use FALLOC_FL_PUNCH_HOLE.

Lack of DIO might be a bigger issue. Then again it's often used by write-heavy workloads which probably don't want to use SMR drives anyway.