> Про checksum=off как бы было. ;)

На вскидку так

/sbin/zfs set checksum=fletcher4 $ZPOOL
/sbin/zfs create -V $SWAPSIZE -o volblocksize=4K $ZPOOL/swap
/sbin/zfs set org.freebsd:swap=on $ZPOOL/swap
/sbin/zfs set checksum=off $ZPOOL/swap
/bin/sync

# Если база на raw разделе (InnoDB)
if [ ! $DBSIZE == "0" ]; then
    /sbin/zfs create -V $DBSIZE -o volblocksize=16K $ZPOOL/innodb # Если raw.
#    /sbin/zfs set recordsize=16K $ZPOOL/innodb # Если не raw.
#    /sbin/zfs set primarycache=metadata $ZPOOL/innodb # Если не raw.
#    /sbin/zfs set secondarycache=none $ZPOOL/innodb # Если не raw.
    /sbin/zfs set logbias=throughput $ZPOOL/innodb
#    /sbin/zfs set sync=disabled $ZPOOL/innodb # отключить ZIL # Если не raw.
fi

/sbin/zfs create -o mountpoint=$MNT/usr><------><------>-o compression=off -o exec=on -o setuid=on<---->$ZPOOL/usr
/sbin/zfs create -o mountpoint=$MNT/usr/home<--><------>-o compression=off -o exec=on -o setuid=off -o nodev $ZPOOL/usr/home
/sbin/zfs create -o mountpoint=$MNT/usr/local<-><------>-o compression=off -o exec=on -o setuid=on<---->$ZPOOL/usr/local
/sbin/zfs create -o mountpoint=$MNT/usr/obj<---><------>-o compression=lzjb -o exec=on -o setuid=on<--->$ZPOOL/usr/obj
/sbin/zfs create -o mountpoint=$MNT/usr/ports<-><------>-o compression=gzip -o exec=on -o setuid=off<-->$ZPOOL/usr/ports
/sbin/zfs create -o mountpoint=$MNT/usr/ports/distfiles>-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/usr/ports/distfiles
/sbin/zfs create -o mountpoint=$MNT/usr/ports/packages<>-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/usr/ports/packages
/sbin/zfs create -o mountpoint=$MNT/usr/src<---><------>-o compression=gzip -o exec=off -o setuid=off<->$ZPOOL/usr/src
/sbin/zfs create -o mountpoint=$MNT/var><------><------>-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/var
/sbin/zfs create -o mountpoint=$MNT/var/audit<-><------>-o compression=lzjb -o exec=off -o setuid=off<->$ZPOOL/var/audit
/sbin/zfs create -o mountpoint=$MNT/var/crash<-><------>-o compression=gzip -o exec=off -o setuid=off<->$ZPOOL/var/crash
/sbin/zfs create -o mountpoint=$MNT/var/db<----><------>-o compression=off  -o exec=off -o setuid=off<->$ZPOOL/var/db
/sbin/zfs create -o mountpoint=$MNT/var/db/pkg<><------>-o compression=lzjb -o exec=off -o setuid=off<->$ZPOOL/var/db/pkg
/sbin/zfs create -o mountpoint=$MNT/var/db/portsnap<--->-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/var/db/portsnap
/sbin/zfs create -o mountpoint=$MNT/var/empty<-><------>-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/var/empty
/sbin/zfs create -o mountpoint=$MNT/var/log<---><------>-o compression=gzip -o exec=off -o setuid=off<->$ZPOOL/var/log
/sbin/zfs create -o mountpoint=$MNT/var/mail<--><------>-o compression=gzip -o exec=off -o setuid=off<->$ZPOOL/var/mail
/sbin/zfs create -o mountpoint=$MNT/var/run<---><------>-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/var/run
/sbin/zfs create -o mountpoint=$MNT/var/tmp<---><------>-o compression=lzjb -o exec=off -o setuid=off<->$ZPOOL/var/tmp
/sbin/zfs create -o mountpoint=$MNT/tmp><------><------>-o compression=lzjb -o exec=off -o setuid=off<->$ZPOOL/tmp

# Если база как обычно
/sbin/zfs create -o mountpoint=$MNT/var/db/mysql<------>-o compression=off -o exec=off -o setuid=off<-->$ZPOOL/var/db/mysql
/sbin/zfs set recordsize=8K $ZPOOL/var/db/mysql
/sbin/zfs set primarycache=metadata $ZPOOL/var/db/mysql
/sbin/zfs set secondarycache=none $ZPOOL/var/db/mysql
/sbin/zfs set logbias=throughput $ZPOOL/var/db/mysql
/sbin/zfs set atime=off $ZPOOL/var/db/mysql

Сейчас думаю о полезности отключения
/sbin/zfs set primarycache
/sbin/zfs set secondarycache
/sbin/zfs set sync=disabled