ZFS get current ARC size

The current statistics data:

cat /proc/spl/kstat/zfs/arcstats

c is the target size of ARC in bytes c_max is the maximum size of the ARC in bytes size is the current size of the ARC in bytes

To change the limit check

cat /sys/module/zfs/parameters/zfs_arc_max

Also, we can check zfs_arc_min in the same directory

We can also set the current zfs_arc_max on the fly by setting the value there.

To set the value to 10GB:

echo "$[10 * 1024*1024*1024]" >/sys/module/zfs/parameters/zfs_arc_max

To permanently change the ARC limit, modify the /etc/modprobe.d/zfs.conf file:

• To set the max value to 8GB:

options zfs zfs_arc_max=8589934592

If the root file system is ZFS, need to update the initramfs every time this value is changed.

update-initramfs -u

Reference:

• https://superuser.com/questions/1137416/how-can-i-determine-the-current-size-of-the-arc-in-zfs-and-how-does-the-arc-rel
• https://pve.proxmox.com/wiki/ZFS_on_Linux, Section: Limit ZFS Memory Usage