ZFS ZFS ARC metadata

[CyberCr33p]

https://docs.freebsd.org/en/books/handbook/zfs/#zfs-advanced writes that vfs.zfs.arc.meta_limit is 1/4 of vfs.zfs.arc.max

But on my system I set sysctl vfs.zfs.arc.max="68719476736" and it shows:

kstat.zfs.misc.arcstats.arc_meta_min: 16777216
kstat.zfs.misc.arcstats.arc_meta_max: 158491984
kstat.zfs.misc.arcstats.arc_dnode_limit: 5153960755
kstat.zfs.misc.arcstats.arc_meta_limit: 51539607552
kstat.zfs.misc.arcstats.arc_meta_used: 130176384

Is the documentation wrong? Because it shows metadata to be 75% of arc max.

Also I see this:

vfs.zfs.arc.meta_limit_percent: 75

 

[Alain De Vos]

Indeed meta-limit is not 25% but 75% of arc-max.

 

[Erichans]

https://docs.freebsd.org/en/books/handbook/zfs/#zfs-advanced writes that vfs.zfs.arc.meta_limit is 1/4 of vfs.zfs.arc.max
Is the documentation wrong? Because it shows metadata to be 75% of arc max.

I think so. Your observations are in line with the OpenZFS documentation; the section for zfs_arc_meta_limit and zfs_arc_meta_limit_percent:

zfs_arc_meta_limit_percent	Notes
[...]
Default	75