How to disable O_DIRECT support?

[rnz]

In zfs 0.8 added support O_DIRECT.
Is there a parameter that allows you to disable O_DIRECT for a pool, dataset, volume?

After added O_DIRECT support in ZFS is very problematic to use ZFS for everyday personal use. There are problems with a whole set of software using O_DIRECT. Constant freezes and general slowdown of programs are just annoying. For example: telegramdesktop/tdesktop#7952

[bghira]

that's a resolved bug in the linked application.

[rnz]

that's a resolved bug in the linked application.

what "that"?

[bghira]

telegram has an issue with how it is writing data to disk, the author of that software patched it. it's not yet released. you can build the beta version to fix it.

this isn't an issue in ZFS. but to answer your original question, zfs set sync=disabled to disable fsync flushing from O_DIRECT.

[rnz]

@bghira 🤦 I know about issue status in telegram - that is my issue. This not this affects only telegram, in general many applications is affected.

this isn't an issue in ZFS. but to answer your original question, zfs set sync=disabled to disable fsync flushing from O_DIRECT.

It doesn't work right. I tried different variants:

2020-05-18.23:01:51 zpool add tank2 log /dev/nvme0n1p4
2020-05-29.21:01:29 zpool set autotrim=on tank2
2020-05-29.21:05:48 zfs set sync=disabled tank2/homes
2020-05-29.21:07:01 zfs set sync=standard tank2/homes
2020-06-15.23:57:15 zfs set sync=disabled tank2/homes
2020-06-16.00:04:11 zfs set sync=disabled tank2
2020-06-16.00:11:45 zfs set sync=standard tank2
2020-06-16.00:11:50 zfs set sync=standard tank2/homes
2020-06-16.00:47:19 zfs set sync=disabled tank2
2020-06-16.00:47:31 zfs set sync=disabled tank2/homes
2020-06-16.01:14:34 zfs set xattr=sa tank2

If applications use O_DIRECT on ZFS - applications wait IO of hdd.