Administrator Guide

Where <y> is the alphabetic number for the multipathing device, <y> is the partition number for this device.
• On SUSE Linux Enterprise Server (SLES) 11.x hosts, a partition node has the format:/dev/mapper/mpath<y>-part<y>
Where <y> is letters assigned to the multipathing device and <y> is the partition number.
• On SLES 10.3 hosts, a partition node has the format: /dev/mapper/mpath<y>_part<y>
Where <y> is one or more letters assigned to the multipathing device and <y> is the partition number.
NOTE: After creating a partition on a device capable of multipathing, all I/O operations, including file system creation,
raw I/O and file system I/O, must be done through the partition node, and not through the multipathing device nodes.
Create file system on Device Mapper partition
Use the standard mkfs command to create the file system on the newly created Device Mapper partition.
For example:
# mkfs –t <filesystem type> /dev/mapper/<partition node>
where <partition node> is the partition on which the file system is created.
Mount a Device Mapper partition
Use the standard mount command to mount the Device Mapper partition, as shown below:
# mount /dev/mapper/<partition_node> <mounting point>
Ready for use
The newly created virtual disks created on the MD Series storage array are now setup and ready to be used. Future reboots automatically
find multipathing devices along with their partitions.
NOTE:
To ensure data integrity protection, reboot a Linux host server attached to an MD Series storage array using the
procedure given below.
Linux host server reboot best practices
It is recommended that you follow the procedures given below when you reboot your Linux host server using Device Mapper multipathing
with an MD Series storage array.
1. Unmount all Device Mapper multipath device nodes mounted on the server: # umount <mounted_multipath_device_node>
2. Stop the Device Mapper multipath service: # /etc/init.d/multipathd stop
3. Flush the Device Mapper multipath maps list to remove any old or modified mappings: # multipath –F
NOTE:
The boot operating system drive may have an entry with the Device Mapper multipathing table. This is not
affected by the multipath –F command.
4. Log out of all iSCSI sessions from the host server to the storage array: # iscsiadm –m node --logout
Important information about special partitions
When using Device Mapper with the MD Series storage arrays, all physical disks are assigned a disk device node. This includes a special
device type used for in-band management of the storage arrays, known as the Access Disk or Universal Xport device.
CAUTION:
Certain commands, such as lsscsi, display one or more instances of Universal Xport devices. These device
nodes must never be accessed, mounted, or used in any way. Doing so can cause loss of communication to the storage
array and possibly cause serious damage to the storage array, potential making data stored on the array inaccessible.
Only multipathing device nodes and partition nodes created using the directions provided above must be mounted or in any way accessed
by the host system or its users.
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Device Mapper multipath for Linux