Bug 284087

Summary:	ZFS: empty usage when -o readonly set on import
Product:	Base System	Reporter:	Dmitry Morozovsky <marck>
Component:	kern	Assignee:	freebsd-fs (Nobody) <fs>
Status:	Open ---
Severity:	Affects Some People	CC:	asomers, markj
Priority:	---
Version:	14.2-STABLE
Hardware:	Any
OS:	Any

Description Dmitry Morozovsky freebsd_committer

2025-01-15 18:15:56 UTC

mostly, subject said it all

found while reviving pool on a dying HDD: alloc and other related statistics are zero:

# zpool import -o readonly=on -R /mnt bext bext-old

# zpool list
NAME       SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
bext-old  3.62T      0  3.62T        -         -     0%     0%  1.00x    ONLINE  /mnt
# df -h | grep bext-old
bext-old/p/distfiles       3.1T    175G    3.0T     5%    /mnt/p/distfiles
bext-old/p/packages        3.3T    349G    3.0T    10%    /mnt/p/data/packages

Comment 1 Mark Johnston freebsd_committer

2025-01-17 16:51:03 UTC

I see the same thing, it works fine if "-o readonly=on" is omitted:

> zpool list
NAME    SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
data   10.9T  4.40T  6.47T        -         -     9%    40%  1.00x    ONLINE  -
zroot  1.80T   111G  1.69T        -         -     0%     6%  1.00x    ONLINE  -

with "data" imported using readonly=on:

> zpool list
NAME    SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
data   10.9T      0  10.9T        -         -     0%     0%  1.00x    ONLINE  -
zroot  1.80T   111G  1.69T        -         -     0%     6%  1.00x    ONLINE  -

This might be worth reporting in the openzfs bug tracker as well.