Setting up multipath and mount disk on linux Redhat 5/6

1    On the machine where you want to setup multipath you first need to find the WWN’s of the FC cards:

[root@admin ~]# cat /sys/class/scsi_host/host*/device/fc_host*/port_name

0x50014380029d41dc

0x50014380029d40b8

The above command is no longer working on redhat 6.

Install Multipath if not install:

[root@admin ~]# yum install device-mapper-multipath

2    Launch modules and add service to startup

[root@admin ~]# modprobe dm-multipath

[root@admin ~]#  service multipathd start

[root@admin ~]#  chkconfig multipathd on

3     Now I have the WWN’s i can add them to my multipath config (/etc/multipathd.conf)

If it daesn’t exist please run :

 [root@admin ~]# /sbin/mpathconf

[root@admin ~]# cp /etc/multipath/.multipath.conf.tmp /etc/multipath.conf

Discover multipath devices :

[root@SVR-IDORA-01 data]# multipath

J

Jul 20 11:02:42 | DM message failed [queue_if_no_path

]

create: mpathc (3600c0ff00010341f7f56fc4f01000000) undef HP,MSA2312fc

size=466G features='0' hwhandler='0' wp=undef

|-+- policy='round-robin 0' prio=50 status=undef

| |- 3:0:0:6 sdr 65:16 undef ready  running

| `- 3:0:1:6 sds 65:32 undef ready  running

`-+- policy='round-robin 0' prio=10 status=undef

  |- 3:0:2:6 sdt 65:48 undef ready  running

  `- 3:0:3:6 sdu 65:64 undef ready  running

[root@SVR-IDORA-01 data]# multipath  -l

mpathc (3600c0ff00010341f7f56fc4f01000000) dm-0 HP,MSA2312fc

size=466G features='1 queue_if_no_path' hwhandler='0' wp=rw

|-+- policy='round-robin 0' prio=-1 status=active

| |- 3:0:0:6 sdr 65:16 active undef running

| `- 3:0:1:6 sds 65:32 active undef running

`-+- policy='round-robin 0' prio=-1 status=enabled

  |- 3:0:2:6 sdt 65:48 active undef running

  `- 3:0:3:6 sdu 65:64 active undef running

       Edit /etc/ multipathd.conf  and paste the configuration below :

defaults {

         user_friendly_names yes

}

 multipaths {

       multipath {

             wwid                3600c0ff00010341f7f56fc4f01000000   (donné par multipath)

             alias               dborapart (pour designer le device multipath)

             path_grouping_policy multibus

             path_checker        readsector0

             path_selector       "round-robin 0"

             failback            manual

             rr_weight           priorities

             no_path_retry       5

       }}

} 

Now i have the default configuration

You should now have your multipath volume in /dev/mapper

or visible by doing

[root@admin ~]# fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes

64 heads, 32 sectors/track, 152627 cylinders

Units = cylinders of 2048 * 512 = 1048576 bytes

Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1         100      102384   83  Linux

/dev/sda2             101      152627   156187648   8e  Linux LVM

Disk /dev/sdd: 49.9 GB, 49999986688 bytes

64 heads, 32 sectors/track, 47683 cylinders

Units = cylinders of 2048 * 512 = 1048576 bytes

Disk /dev/sdd doesn't contain a valid partition table

Disk /dev/sdh: 49.9 GB, 49999986688 bytes

64 heads, 32 sectors/track, 47683 cylinders

Units = cylinders of 2048 * 512 = 1048576 bytes

Disk /dev/sdh doesn't contain a valid partition table

Disk /dev/sdl: 49.9 GB, 49999986688 bytes

64 heads, 32 sectors/track, 47683 cylinders

Units = cylinders of 2048 * 512 = 1048576 bytes

Disk /dev/sdl doesn't contain a valid partition table

Disk /dev/sdp: 49.9 GB, 49999986688 bytes

64 heads, 32 sectors/track, 47683 cylinders

Units = cylinders of 2048 * 512 = 1048576 bytes

Disk /dev/sdp doesn't contain a valid partition table

Disk /dev/dm-3: 49.9 GB, 49999986688 bytes

255 heads, 63 sectors/track, 6078 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

5 

          Now you can see your new volume, in this case /dev/dm-3, sometime in Redhat 6 you’ll see “mpath” follow by a, b or c depending on the number of volume.

Create new partition (do these  steps if you can restart  your server or go to step 6) :

[root@admin ~]# fdisk /dev/dm-3 or /dev/mapper/mpathb

Next type “n” and (press enter)

Choose “p” option then press enter.

Choose “1” partition and press enter 3 times

Finally type “w” to write changes.

On linux you need to restart the OS to apply the change to the table of partition.

[root@admin ~]# fdisk –l

You’ll see new partitions like /dev/mapper/mpathbp1 or /dev/dm-3p1

6     once the new partition is created you can create filesystem

[root@admin ~]# mkfs.ext3 /dev/dm-3p1

and finally mount your volume somewhere

[root@admin ~]# mount /dev/dm-3p1 /mnt/myvolume