zfs create -V 32G -b 32k -o logbias=throughput -o sync=always -o primarycache=metadata  pool/swap
mkswap  /dev/zvol/pool/swap
swapon /dev/zvol/pool/swap
sysctl -w vm.swappiness=20

root@truenas:/mnt/pool/oliutyi# free -m
               total        used        free      shared  buff/cache   available
Mem:           11696        8829         899          17        2303        2867
Swap:          32767           0       32767