14 November 2011

mdadm raid0: ext3 vs ext4

I did a little test, between the ext3 and ext4 writing speed, on an mdadm device. I’m documenting only the best/worst results. In both cases, best speed was obtained with the “64” chunk size. The worst one was obtained with chunk size “8”.
The test was done with 2 Western Digital VelociRaptor disks, 10k RPM, 150GB each.
ext3 - 8k
# dd if=/dev/zero of=/mnt/md0/test bs=1024 count=1M
1048576+0 records in
1048576+0 records out
1073741824 bytes (1.1 GB) copied, 2.10997 s, 509 MB/s
# dd if=/dev/zero of=/mnt/md0/test bs=1024 count=10M
10485760+0 records in
10485760+0 records out
10737418240 bytes (11 GB) copied, 50.8113 s, 211 MB/s

ext4 - 8k
# dd if=/dev/zero of=/mnt/md0/test bs=1024 count=1M
1048576+0 records in
1048576+0 records out
1073741824 bytes (1.1 GB) copied, 1.58119 s, 679 MB/s
# dd if=/dev/zero of=/mnt/md0/test bs=1024 count=10M
10485760+0 records in
10485760+0 records out
10737418240 bytes (11 GB) copied, 45.2483 s, 237 MB/s

ext3 - 64k
# dd if=/dev/zero of=./test bs=1024 count=1M
1048576+0 records in
1048576+0 records out
1073741824 bytes (1.1 GB) copied, 2.00814 s, 535 MB/s
# dd if=/dev/zero of=./test bs=1024 count=10M
10485760+0 records in
10485760+0 records out
10737418240 bytes (11 GB) copied, 50.9694 s, 211 MB/s

ext4 - 64k
# dd if=/dev/zero of=/mnt/md0/test bs=1024 count=1M
1048576+0 records in
1048576+0 records out
1073741824 bytes (1.1 GB) copied, 1.56012 s, 688 MB/s
# dd if=/dev/zero of=/mnt/md0/test bs=1024 count=10M
10485760+0 records in
10485760+0 records out
10737418240 bytes (11 GB) copied, 44.9892 s, 239 MB/s
To create the array I used the following command:
# mdadm --create /dev/md0 --chunk=SIZE --level=raid0 --raid-devices=2 /dev/sdb /dev/sdc

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