IBM System storage DS6000 Series, Attachment Manual

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2. To make the devices available permanently, after a reboot, you must create a
new initial ramdisk (RAM that is accessed like a disk) that contains the
necessary modules and parameter information. First, save the module
parameters in the configuration file /etc/zfcp.conf, as shown in Figure 52.
3. Next, create a new ramdisk with the mk_initrd utility and then run the zipl utility
to update the initial program load record to point to the new ramdisk.
4. Enable multipath support, which is provided by the logical volume manager
kernel for Linux z/FCP.
a. Create physical volumes with the following commands:
pvcreate /dev/sda1
pvcreate /dev/sdb1...
b. Put the physical volumes into a volume group with the following command:
vgcreate fcpvg /dev/sda1 /dev/sdb1...
c. Create as many logical volumes as you want with the following command:
lvcreate --size 16G fcpvg
d. Enable the alternate paths to the physical volumes with the pvpath
command.
pvpath --path0 --enable y /dev/sda1
pvpath --path1 --enable y /dev/sda1
If both paths have a weight of 0, they will loadbalance.
5. These configurations will yield the SCSI device /dev/sda - /dev/sdc accessed
on the first path and the SCSI device
/dev/sdd - /dev/sdf
accessed on the
second path, as shown in Figure 53.
linuxa:~#echo "0x0600 0x00000001:0x5005076300c89589 \
0x00000001:0x5302000000000000">/proc/scsi/zfcp/add_map
linuxa:~#echo "scsi add-single-device 0 0 1 1">/proc/scsi/scsi
Figure 51. Example of how to add SCSI devices through the add_map command
linuxa:~#cat /proc/scsi/zfcp/map >/etc/zfcp.conf
linuxa:~#cat /etc/zfcp.conf
0x0600 0x00000001:0x5005076300c89589 0x00000000:0x5301000000000000
0x0600 0x00000001:0x5005076300c89589 0x00000001:0x5302000000000000
0x0600 0x00000001:0x5005076300c89589 0x00000002:0x5300000000000000
Figure 52. Saving the module parameters in the /etc/zfcp.conf file
rmmod zfcp modprobe qdio modprobe scsi_mod insmod zfcp map="\ 0x0600 1:0x5005076300c89589
0:0x5301000000000000;\ 0x0600 1:0x5005076300c89589 1:0x5302000000000000;\
0x0600 1:0x5005076300c89589 2:0x5300000000000000;\ 0x0700 1:0x5005076300ca9589
0:0x5301000000000000;\ 0x0700 1:0x5005076300ca9589 1:0x5302000000000000;\
0x0700 1:0x5005076300ca9589 2:0x5300000000000000" modprobe sd_mod
Figure 53. Example of Logical Volume Manager Multipathing
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DS6000 Host Systems Attachment Guide