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Disk Alignment and perf testing in Linux

It should be noted that I am JUST starting to educate myself on testing performance of disks.  Do NOT assume that what I am doing here is the work of someone that actually knows about this topic.

I decided that Bonnie (or Bonnie++ more accurately) would be the tool I use, in addition to benchmarking a mkfs and dd of /dev/zero.

    wget http://www.coker.com.au/bonnie++/bonnie++-1.03e.tgz
    tar -xvzf bonnie++-1.03e.tgz
    cd bonnie++-1.03e
    ./configure
    make && make install

On my system I have 2 LUNs from the same array.  I am assuming they are on the same, or similar, RAID Parity Groups on the Array. 

My concern is that a misaligned partition table and partitions would have a noticeable performance impact.

[root@dvgllprhvsrv91 sysadmin]# parted -s /dev/dm-6 mklabel msdos mkpart primary ext3 2048s 100%
[root@dvgllprhvsrv91 sysadmin]# parted -s /dev/dm-5 mklabel msdos mkpart primary ext3 0 100%
Warning: The resulting partition is not properly aligned for best performance.

Test 1 -- dm-6 (aligned), dm-5 (not-aligned)

Once I added the partition I ended up with the following diskmapper devices:
dm-6 -> dm-14 (aligned)
dm-5 -> dm-15 (not-aligned)

I mounted them as /dev/dm-14 and /dev/dm-15 (respectively).

[root@dvgllprhvsrv91 sysadmin]# time mkfs /dev/dm-14
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
3276800 inodes, 13106944 blocks
655347 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
400 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
    4096000, 7962624, 11239424

Writing inode tables: done                           
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

real    0m3.836s
user    0m0.016s
sys    0m1.087s
[root@dvgllprhvsrv91 sysadmin]# time mkfs /dev/dm-15
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
3276800 inodes, 13107199 blocks
655359 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
400 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
    4096000, 7962624, 11239424

Writing inode tables: done                           
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

real    0m5.537s
user    0m0.010s
sys    0m5.017s
[root@dvgllprhvsrv91 sysadmin]# dd if=/dev/zero of=/mnt/dm-14/test bs=512 count=3072000
3072000+0 records in
3072000+0 records out
1572864000 bytes (1.6 GB) copied, 4.40712 s, 357 MB/s
[root@dvgllprhvsrv91 sysadmin]# dd if=/dev/zero of=/mnt/dm-15/test bs=512 count=3072000
3072000+0 records in
3072000+0 records out
1572864000 bytes (1.6 GB) copied, 4.41995 s, 356 MB/s
[root@dvgllprhvsrv91 bonnie++-1.03e]# bonnie++ -d /mnt/dm-14/ -s 2g -r1g -n 0 -m localhost -f -b -u root
Using uid:0, gid:0.
Writing intelligently...done
Rewriting...done
Reading intelligently...done
start 'em...done...done...done...
Version 1.03e       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
localhost        2G           262728  26 267633  20           2287646 100 +++++ +++
localhost,2G,,,262728,26,267633,20,,,2287646,100,+++++,+++,,,,,,,,,,,,,
[root@dvgllprhvsrv91 bonnie++-1.03e]# bonnie++ -d /mnt/dm-15/ -s 2g -r1g -n 0 -m localhost -f -b -u root
Using uid:0, gid:0.
Writing intelligently...done
Rewriting...done
Reading intelligently...done
start 'em...done...done...done...
Version 1.03e       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
localhost        2G           243774  25 243384  20           2359965  99 +++++ +++
localhost,2G,,,243774,25,243384,20,,,2359965,99,+++++,+++,,,,,,,,,,,,,




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