Welcome to Linux Forums! With a comprehensive Linux Forum, information on various types of Linux software and many Linux Reviews articles, we have all the knowledge you need a click away, or accessible via our knowledgeable members.
Find the answer to your Linux question:
Write an article for LinuxForums Today! Win Great Prizes!
Device Mapper Multipath (DM-MP) allows nodes to route I/O over multiple paths to a storage controller. A path refers to the connection from an HBA port to a storage controller port. As paths fail and new paths come up, DM-MP reroutes the I/O over the available paths.
By Syed Asim Abbas
asimabbas31@gmail.comThis e-mail address is being protected from spambots. You need JavaScript enabled to view it
Easy way to configure Multipathing ------------------------------------
Disk /dev/sda: 60.0 GB, 60011642880 bytes 255 heads, 63 sectors/track, 7296 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x3f443f43
Device Boot Start End Blocks Id System
Disk /dev/sdg: 107.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdn: 107.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdh: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdo: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
MultiPathing packaged avilable on Distribution
###Check the SCSI IDs to see the disk are pairs. /dev/sda is my system disk so no need to configure it for multipathing. Sdg , sdn, sdh and sdo are SAN connected disks.
###To implement multipath environment, you must define the alias names for the multipath devices by editing the multipath.conf file that resides in the /etc/ directory:
[root@power root]# vi /etc/multipath.conf
# Blacklist all devices by default. Remove this to enable multipathing # on the default devices. blacklist { devnode "*" }
##############Comment The above lines
# Blacklist all devices by default. Remove this to enable multipathing # on the default devices. #blacklist { # devnode "*" #}
#########Define the Disks Aliases ##########
multipaths {
multipath { wwid 360060e8005bcaf000000bcaf00006024 alias ora1 }
multipath { wwid 360060e8005bcaf000000bcaf00005033 alias ora2 }
}
####### Save the configuration
[root@power root]# chkconfig multipathd on
[root@power root]# service multipathd restart Stopping multipathd daemon: [FAILED] Starting multipathd daemon: [ OK ] [root@power root]#
[root@power root]# fdisk -l
Disk /dev/sda: 60.0 GB, 60011642880 bytes 255 heads, 63 sectors/track, 7296 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x3f443f43
Device Boot Start End Blocks Id System
Disk /dev/sdg: 107.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdn: 107.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdh: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdo: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
##########No update same result. Restart the system and run fdisk -l
[root@power root]# fdisk -l
Disk /dev/sda: 60.0 GB, 60011642880 bytes 255 heads, 63 sectors/track, 7296 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk identifier: 0x3f443f43
Device Boot Start End Blocks Id System
Disk /dev/sdg: 107.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdn: 107.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdh: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/sdo: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/dm-0: 70.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/dm-1: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/mpath/ora1: 70.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
Disk /dev/mpath/ora2: 153.0 GB, 60011642880 bytes Device Boot Start End Blocks Id System
#########Ok four more disks are aviavlable. Don't confude just used your paths /dev/mpath/ora1 /dev/mpath/ora2
[root@power root]# ls /dev/mpath*
ora1 ora2
####Disks multipath names are available now. Mount the devices using new name.
[root@power root]# mount /dev/mpath/ora1 /ora1
[root@power root]# mount /dev/mpath/ora2 /ora2
For testing unplugged one fiber link and see the results.
Comments about this article
useful article, thanks
writen by: speculatrix on 2010-05-17 09:12:03
useful article, includes the important basics
RE: useful article, thanks written by speculatrix:
Comment title: * please do not put your response text here
Submit Your Article
Latest Articles
Editor's Choice
Article Categories
Join Linux Forums Today
Win Great Prizes
User Score
Editor Score
Tools »
Bookmark
Share
Comment