[7.2.0] ZFS NVMe Mirror Throttling on Single-Container Writes — Fixed by Downgrade to 7.1.x

Minor

TL;DR: After upgrading to Unraid 7.2.0, a single MakeMKV export on a 2× Crucial P310 ZFS mirror stalls every 5–10s (%util=99%, w_await=25ms). All other Dockers off. Downgrading to 7.1.x restored 500+ MB/s with zero throttling.

ARC was auto changed to 2GB after upgrade:
ARC size: 2.0 GB (capped despite 32 GB RAM)

ARC miss %: 27.9%

Test	Result
All other Dockers stopped	No change
`zfs set sync=disabled`	No improvement
`recordsize=1M`, `atime=off`	Minor help, not fix
G6 camera in HA paused	No impact

Followers

Status Definitions

Open = Under consideration.

Solved = The issue has been resolved.

Solved version = The issue has been resolved in the indicated release version.

Closed = Feedback or opinion better posted on our forum for discussion. Also for reports we cannot reproduce or need more information. In this case just add a comment and we will review it again.

Retest = Please retest in latest release.

Priority Definitions

Minor = Something not working correctly.

Urgent = Server crash, data loss, or other showstopper.

Annoyance = Doesn't affect functionality but should be fixed.

Other = Announcement or other non-issue.

[7.2.0] ZFS NVMe Mirror Throttling on Single-Container Writes — Fixed by Downgrade to 7.1.x

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