livecd ~ # mdadm --create /dev/md1 --level=0 --raid-devices=2 /dev/sd[ac]2
mdadm: array /dev/md1 started.
livecd ~ # mdadm --create /dev/md4 --level=0 --raid-devices=2 /dev/hd[eg]2
mdadm: array /dev/md4 started.
livecd ~ # mkfs.jfs -j /dev/md4 /dev/md1
mkfs.jfs version 1.1.8, 03-May-2005
Warning!  All data on device /dev/md1 will be lost!
Warning!  All data on device /dev/md4 will be lost!

Continue? (Y/N) Y
   \

Format completed successfully.

20000768 kilobytes total disk space.
livecd ~ # mount -o noatime /dev/md1 /mnt/tmp
livecd ~ # dd if=/dev/zero of=/mnt/tmp/test.test bs=4096 count=1024k
1048576+0 records in
1048576+0 records out
4294967296 bytes (4.3 GB) copied, 49.5607 s, 86.7 MB/s    <<<< JFS WRITE SPEED
livecd ~ # dd of=/dev/null if=/mnt/tmp/test.test
8388608+0 records in
8388608+0 records out
4294967296 bytes (4.3 GB) copied, 60.5259 s, 71.0 MB/s    <<<< JFS READ SPEED

livecd ~ # mke2fs -b 4096 -O journal_dev /dev/md4
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
0 inodes, 32096 blocks
0 blocks (0.00%) reserved for the super user
First data block=0
0 block group
32768 blocks per group, 32768 fragments per group
0 inodes per group
Superblock backups stored on blocks: 

Zeroing journal device: done                            
livecd ~ # mkfs.ext3 -J device=/dev/md4 -E stride=32 -b 4096 /dev/md1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
2501856 inodes, 5000192 blocks
250009 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=8388608
153 block groups
32768 blocks per group, 32768 fragments per group
16352 inodes per group
Superblock backups stored on blocks: 
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
        4096000

Writing inode tables: done                            
Adding journal to device /dev/md4: done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 37 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
livecd ~ # mount -o noatime /dev/md1 /mnt/tmp
livecd ~ # dd if=/dev/zero of=/mnt/tmp/test.test bs=4096 count=1024k
1048576+0 records in
1048576+0 records out
4294967296 bytes (4.3 GB) copied, 53.4932 s, 80.3 MB/s    <<<< EXT3 WRITE SPEED
livecd ~ # dd of=/dev/null if=/mnt/tmp/test.test
8388608+0 records in
8388608+0 records out
4294967296 bytes (4.3 GB) copied, 60.9702 s, 70.4 MB/s    <<<< EXT3 READ SPEED