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Date: Fri, 15 Jul 2022 00:33:25 -0500
From: "Zane C. B-H" <v.velox@vvelox.net>
To: emulation@freebsd.org
Subject: bhyve, ZFS, and disk IO stats
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So with bhyve, is there any good way to get disk IO stats for a VM when 
it is
using ZFS for a dataset.

Apparently ZFS only tracks RW stats for mounted disks, but not raw disks 
stored
as a ZFS dataset. Below is a running VM, but the stats reported are all 
zero.

kstat.zfs.storage.dataset.objset-0x1d41.nread: 0
kstat.zfs.storage.dataset.objset-0x1d41.reads: 0
kstat.zfs.storage.dataset.objset-0x1d41.nwritten: 0
kstat.zfs.storage.dataset.objset-0x1d41.writes: 0
kstat.zfs.storage.dataset.objset-0x1d41.dataset_name: 
storage/debian10_test/dsk1.vhd

Can't use gstat as ZFS datasets don't show up as GEOM devices it 
appears.

iostat has the same issue.

'zfs get all' for the dataset in question does not return any RW stats.

Any one have any thoughts on this?