24
•
Once the LUNs that will be virtualized to IBM i have reported in VIOS, change their queue
depth to improve performance. Start a Telnet session to VIOS and log as
padmin
. Use
the following command for each LUN (hdisk1 in this example):
o
chdev -dev hdisk1 -perm -attr queue_depth=32
•
Another parameter that can improve performance is the number of I/O commands to
send to the QLogic CFFh Fibre Channel adapter. The recommended value is 512. Be
sure to change the value for both ports of the CFFh adapter:
o
chdev –dev fcs0 –attr num_cmd_elems=512 –perm
o
chdev –dev fcs1 –attr num_cmd_elems=512 –perm
•
To improve reliability, enable dynamic tracking for the LUNs virtualized to IBM i. Do so
for both ports of the CFFh adapter:
o
chdev –dev fscsi0 –attr dyntrk=yes –perm
o
chdev –dev fscsi1 –attr dyntrk=yes –perm
Using the
–perm
option in the above commands means that the value will be updated only in the
VIOS device configuration database (ODM). To make the change effective, reboot VIOS when
there is downtime available for all client partitions.
4.3. Create LUNs for the IBM i partition(s) in BladeCenter H
To create LUNs for IBM i (virtualized by VIOS) on DS3400, follow the instructions in chapter 8 of
the Redbook
IBM System Storage DS3000: Introduction and Implementation Guide (SG247065)
,
available here: http://www.redbooks.ibm.com/redpieces/abstracts/sg247065.html?Open.
To create LUNs for IBM i (virtualized by VIOS) on DS3950, DS4700, DS4800, DS5020, DS5100
or DS5300, follow the instructions in chapter 3 of the Redbook
IBM Midrange System Storage
Implementation and Best Practices Guide (SG246363)
, available here:
http://www.redbooks.ibm.com/redbooks/pdfs/sg246363.pdf
.
To create LUNs for IBM i (virtualized by VIOS) on DS8000, follow the instructions in section 3 of
the Redbook
IBM System Storage DS8000 Series: Architecture and Implementation (SG246786)
,
available here: http://www.redbooks.ibm.com/redpieces/abstracts/sg246786.html?Open.
To create LUNs for IBM i (virtualized by VIOS) on the SAN Volume Controller (SVC), follow the
instructions in section 10 of the Redbook
Implementing the IBM System Storage SAN Volume
Controller V4.3 (SG246423),
available here:
http://www.redbooks.ibm.com/abstracts/sg246423.html?Open.
To create LUNs for IBM i (virtualized by VIOS) on the XIV storage subsystem, follow the
instructions in Chapter 4 of the Redbook
IBM XIV Storage System: Architecture, Implementation,
and Usage (SG247659),
available here:
http://www.redbooks.ibm.com/abstracts/sg247659.html?Open.
4.4. Multi-path I/O (MPIO) for IBM i in BladeCenter H
MPIO refers to the capability of an operating system to use two separate I/O paths to access
storage, typically Fibre Channel or SAS. For IBM i on blade, that capability resides with VIOS,
because IBM i is not directly accessing the SAN. Additionally, IBM i does not currently support
having two paths to the virtual disk units (LUNs) in VIOS from a virtual client/server perspective.
