mirrors/zfs: Tune more kernel parameters as BFSU did

docs/services/mirrors/zfs.md

@@ -7,8 +7,24 @@
 For OpenZFS 2.2:
 
 ```shell title="/etc/modprobe.d/zfs.conf"
+# Set ARC size to 150 GiB
 options zfs zfs_arc_max=161061273600
 options zfs zfs_arc_min=161061273600
+
+# Allow up to 80% of ARC to be used for dnodes 
+options zfs zfs_arc_dnode_limit_percent=80
+
+# See man page section "ZFS I/O Scheduler"
+options zfs zfs_vdev_async_read_max_active=8
+options zfs zfs_vdev_async_read_min_active=2
+options zfs zfs_vdev_scrub_max_active=5
+options zfs zfs_vdev_max_active=20000
+
+# Never throttle the ARC
+options zfs zfs_arc_lotsfree_percent=0
+
+# Tune L2ARC
+options zfs l2arc_headroom=8
 options zfs l2arc_write_max=67108864
 options zfs l2arc_noprefetch=0
 ```