2010-05-10.  Simple (write)speed-tests when making ext[34] filesystems on a pair
of disks of a very-missing (2 data disks, no parity) raid6 array.


220MB tar of ~440MB gentoo portage tree

mdadm --create /dev/md1 -c 16 -l 6 -n 4 /dev/sd[bc]3 missing missing
time mkfs.ext3 -L system -b 4096 -E stride=2,stripe-width=4 -m 2 /dev/md0
mount -t ext3 -o rw,erroos=remount-ro,data=ordered,barrier=1,commit=4 /dev/md0 /mnt/dsk/

df -m . ;  time tar -xf /root/z ; df -m . ; time sync
25s + ~15-20s sync
24s + 16s second time (into subdir)

umount dsk/
mount -t ext3 -o rw,errors=remount-ro,data=ordered,barrier=1,commit=60 /dev/md0 /mnt/dsk/

df -m . ;  time tar -xf /root/z ; df -m . ; time sync
57s + 23s sync  !!!
20s + 14s second time


umount dsk/
mount -t ext3 -o rw,errors=remount-ro,data=ordered,barrier=0,commit=60 /dev/md0 /mnt/dsk/

df -m . ;  time tar -xf /root/z ; df -m . ; time sync
20s + 18s
65s + 26s second time

umount dsk/
mount -t ext3 -o rw,errors=remount-ro,data=writeback,barrier=1,commit=4 /dev/md0 /mnt/dsk/

df -m . ;  time tar -xf /root/z ; df -m . ; time sync
14s + 27s
13s + 21s second time


umount dsk/
time mkfs.ext4 -L system -b 4096 -E stride=2,stripe-width=4 -m 2 /dev/md0
(took 9s)

mount -t ext4 -o rw,errors=remount-ro,data=ordered,barrier=1,commit=4 /dev/md0 /mnt/dsk/
df -m . ;  time tar -xf /root/z ; df -m . ; time sync
7s + 9.5s
6s + 10s


umount dsk/
mount -t ext4 -o rw,errors=remount-ro,data=writeback,barrier=1,commit=4 /dev/md0 /mnt/dsk/

df -m . ;  time tar -xf /root/z ; df -m . ; time sync
7s + 9s

umount dsk/
mount -t ext4 -o rw,errors=remount-ro,data=journal,barrier=1,commit=4 /dev/md0 /mnt/dsk/

df -m . ;  time tar -xf /root/z ; df -m . ; time sync
30s + 2s

-----------------
Any conclusion?  Only that ext4 has big advantages (at least for this writing-based small-file
situation) over ext3, and that the barrier/commit/data options do little harm to performance
apart from (obviously) data=journal.
-----------------


mdadm --create /dev/md0 -c 16 -l 6 -n 4 /dev/sd[bc]2 missing missing
mkfs.ext4 -L system -b 4096 -E stride=4,stripe-width=8 -m 2 /dev/md0
tune2fs -c0 -i0 /dev/md0
mount -t ext4 -o rw,errors=remount-ro,data=ordered,journal_checksum,barrier=1,stripe=8,commit=5 /dev/md0 /mnt/dsk/

mdadm --create /dev/md1 -c 16 -l 6 -n 4 /dev/sd[bc]3 missing missing
mkfs.ext4 -L home -b 4096 -E stride=4,stripe-width=8 -m 2 /dev/md1
tune2fs -c0 -i0 /dev/md1
mount -t ext4 -o rw,errors=remount-ro,data=ordered,journal_checksum,barrier=1,stripe=8,commit=5 /dev/md1 /mnt/dsk/home/

mdadm --create /dev/md2 -c 64 -l 6 -n 4 /dev/sd[bc]4 missing missing
mkfs.ext4 -L public -b 4096 -E stride=16,stripe-width=32 -m 2 /dev/md2
tune2fs -c0 -i0 /dev/md2
mount -t ext4 -o rw,errors=remount-ro,data=ordered,journal_checksum,barrier=1,stripe=32,commit=5 /dev/md1 /mnt/dsk/home/public