SAN Boot Implementation and Best Practices Guide ... - IBM Redbooks

Draft Document for Review June 27, 2012 9:05 am 7958ch05_DS8000.fm
In other cases, after rebooting, if your server started without the multipath, you need to
configure the Multipath tool to identify and work with the Luns from DS8000 Subsystem.
Follow the below steps to configure the multipath tool:
Check/install the multipath packages was installed fine. Use the rpm -qa command as
shown Example 3-3.
Example 3-3 checking the multipath packages
rb1sanboot:~ # rpm -qa|grep mapper
device-mapper-1.02.27-8.6
device-mapper-32bit-1.02.27-8.6
rb1sanboot:~ # rpm -qa|grep multi
multipath-tools-0.4.8-40.1
Change or create the /etc/multipath.conf using the IBM recommendation for DS8000 as
shown Example 3-4.
Example 3-4 creating the multipath.conf file.
rb1sanboot:/etc # vi /etc/multipath.conf
devices {
lling_interval 30
failback immediate
no_path_retry 5
rr_min_io 100
path_checker tur
user_friendly_names yes
}
devices {
# These are the default settings for 2107 (IBM DS8000)
# Uncomment them if needed on this system
device {
vendor "IBM"
product "2107900"
path_grouping_policy group_by_serial
}
}
:wq
rb1sanboot:/etc #
Edit the /etc/sysconfig/kernel adding the dm-multipath as shown Example 3-5.
Example 3-5 Editing the /etc/sysconfig/kernel
rb1sanboot:~ # vi /etc/sysconfig/kernel
## Description:
## Type: string
## Command: /sbin/mkinitrd
#
# This variable contains the list of modules to be added to the initial
# ramdisk by calling the script "mkinitrd"
# (like drivers for scsi-controllers, for lvm or reiserfs)
#
Chapter 3. SAN Boot implementation with IBM System Storage DS8000 169