test, with single ramdisk, comparing UFS to ZFS

800 MB/s limit test, with single ramdisk, comparing UFS to ZFS, using dd

/sbin/mdconfig -d -u md0
/sbin/mdconfig -a -t swap -s 8g -u md0

zpool create zram /dev/md0
zfs set atime=off zram

cd /zram
gdd if=/tank/bcnasvm1/images/openSUSE-11.4-DVD-x86_64.iso of=testfile bs=1M conv=fdatasync
    4614782976 bytes (4.6 GB) copied, 4.55347 s, 1.0 GB/s

zfs umount zram
zfs mount zram
gdd if=zram/testfile of=/dev/null bs=1M
    4614782976 bytes (4.6 GB) copied, 2.33942 s, 2.0 GB/s

newfs /dev/md0
cd /mnt
mkdir test
mount /dev/md0 test
gdd if=/tank/bcnasvm1/images/openSUSE-11.4-DVD-x86_64.iso of=test/testfile bs=1M conv=fdatasync
    4614782976 bytes (4.6 GB) copied, 4.26242 s, 1.1 GB/s


umount test
mount /dev/md0 test
ls -l test
find test
gdd if=test/testfile of=/dev/null bs=1M
    4614782976 bytes (4.6 GB) copied, 4.34821 s, 1.1 GB/s

# read cache problem
gdd if=test/testfile of=/dev/null bs=1M
    4614782976 bytes (4.6 GB) copied, 1.02903 s, 4.5 GB/s

# read cache clearing hack
cd test
umount /mnt/test
    umount: unmount of /mnt/test failed: Device busy
cd ..
gdd if=test/testfile of=/dev/null bs=1M
    4614782976 bytes (4.6 GB) copied, 5.74366 s, 803 MB/s