{{parent page="FileSystem"}}

===File System Striping===
This can be useful for building filesystem(s) for a database system. I will be using lvm to stripe data across disks. To enable stripping, one should have RAID as underlying storage to reduce the chances of loosing the entire volume because of a single disk failure.

==Create physical volumes==
Supposedly you have an underlying storage system, say RAID-10 on a hardware controller. Divide it into 3 equal parts and prep them for LVM use

%%
pvcreate /dev/cciss/c0d1p1
pvcreate /dev/cciss/c0d1p2
pvcreate /dev/cciss/c0d1p3
%%

==Create volume groups==
This is boring. If the volumes are not storing big files, a 4M extent should be sufficient

%%
vgcreate -s4M vg0 /dev/cciss/c0d1p1 /dev/cciss/c0d1p2 /dev/cciss/c0d1p3
%%

==Create logical volumes==
The interleave option here is important. This ensures IO are spread across the 3 PV's

%%
lvcreate -i3 -I128K -L50G -ndata vg0
lvcreate -i3 -I128K -L5G -nlog vg0
%%

==Create filesystem==
mkfs...

==Benchmark==
# bonnie+ + -d /mountpoint -r 512 -u root -s 2g -n0 -q -f -b

**Without LVM striping**
%%
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
abox 2G 91039 24 82257 14 2203381 100 +++++ +++
abox,2G,,,91039,24,82257,14,,,2203381,100,+++++,+++,,,,,,,,,,,,,
%%

**With LVM striping**
Write is 40% faster!
%%
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
bbox 2G 126815 34 132786 23 2309730 99 +++++ +++
bbox,2G,,,126815,34,132786,23,,,2309730,99,+++++,+++,,,,,,,,,,,,,
%%

**3par**
%%
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
cbox 2G 316609 67 346639 50 2817900 99 +++++ +++
cbox,2G,,,316609,67,346639,50,,,2817900,99,+++++,+++,,,,,,,,,,,,,
%%

**3par w/ lvm stripping**
strange, write thruput has reduced here
%%
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
dbox 2G 179441 43 190579 30 2841138 100 +++++ +++
dbox,2G,,,179441,43,190579,30,,,2841138,100,+++++,+++,,,,,,,,,,,,,
%%