Linux Config.fm Draft Document for Review March 28, 2011 12:24 pm
640  IBM System Storage DS3500: Introduction and Implementation Guide
Command (m for help): n
Command action    
   e   extended   
   p   primary partition (1-4)
p                 
Partition number (1-4): 1     
First cylinder (1-15360, default 1): 
Using default value 1              
Last cylinder, +cylinders or +size{K,M,G} (1-15360, default 15360): +100M
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.     
We now need to create a map from the previous partition table. In order to do that, run the 
following command:
# kpartx -a /dev/mapper/mpath0
List the /dev/mapper directory and the partitions on /dev/dm-0 to verify the correct partitioning 
as shown in Example 20-15.
Example 20-15   very the partitioning
# ls /dev/mapper/ 
control  mpath0  mpath0p1 
# fdisk -l /dev/dm-0
Disk /dev/dm-0: 16.1 GB, 16106127360 bytes
64 heads, 32 sectors/track, 15360 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0xebba465c
     Device Boot      Start         End      Blocks   Id  System
/dev/dm-0p1               1         101      103408   83  Linux
The last step is to format the partition and mount it with the following commands:
# mkfs.ext3 /dev/mapper/mpath0p1
# mount /dev/mapper/mpath0p1 /mnt
Removing Virtualized Devices
The following multipath commands will âflushâ all unused device mappings and it is not 
possible to run this command if the device is mounted.
multipath -F
Important: You must make sure you are running IO to the virtual devices created by device 
mapper, and not the physical device paths. If you are running IO to the physical paths, 
device mapper will not be able to manage a failover and the IO will fail.