Limited "ZFS File Data" with zfs_arc_max

Hello,

On our T6320,  I created a New LDom with 2GB Memory and include a ZFS Filesystem to host our application. Then , I wanted to limited the physical Memory take by all ZFS Filesystem.
To do that I added in the /etc/system these both variables "set zfs:zfs_arc_max = 0x19000000" "set zfs:zfs_arc_min = 0x19000000" to allow just 400MB on Memory.
After reboot we can see in "mdb -k  ::memstat" that the memory used by "ZFS File Data" was  177MB (Good Point).
Then, I started a FlashArchives to backup the system (we do it every night) rpool, and check if the memory growed. I saw with astonishment that the memory grow quickly until 513MB.