Table of Contents
Advertisement
•
Controller firmware 07.60.28.00 or later
•
DS Storage Manager 10.60.x5.17 or later
•
IBM i Host Attachment Kit, FC #7735 (required)
•
Storage Partitioning (strongly recommended)
16.3. Best practices, limitations and performance
As with other storage subsystems, it recommended to create LUNs for IBM i production
workloads on FC drive RAID arrays only in order to meet the performance requirements of the
application. While SATA drives are supported for direct attachment to IBM i, they are best suited
for test, development and archival IBM i workloads. Mixing of FC and SATA drives within an
enclosure is supported. Solid-state drives are not presently supported for IBM i direct attachment,
but IBM i is investigating offering that support. Hardware encryption of the data on the physical
drives within the storage subsystem is supported.
All LUNs mapped directly to IBM i must be protected. Therefore, the supported RAID levels for
IBM i direct attachment are 1, 5 and 6. LUNs report as protected in IBM i; therefore, IBM i
mirroring is not possible. The reliability of the solution is based on the RAID protection within the
storage subsystem and on using multiple paths. The maximum LUN size for IBM i in this
environment is up to but not including 2TB. A maximum of 64 LUNs per FC adapter port is
supported; this statement is identical to that for DS8000 direct attachment. Dynamic volume
(LUN) expansion is not supported for IBM i. Once LUNs have been mapped to IBM i, at most 300
from the same subsystem can be added to an Auxiliary Storage Pool (ASP) with a single
operation. More than 300 LUNs can be added to an ASP in general, but they require multiple add
operations.
There are no special requirements for the load source LUN, except of course sufficient size to
qualify as a load source for IBM i 6.1. The load source does not need to be the very first LUN
mapped to IBM i. When performing an Initial Program Load (IPL), an active path to the load
source LUN is required. Path failover is not possible during IPL; however, once IPL is complete,
failover functionality resumes.
As with other host types, each port on a Fibre Channel adapter in IBM i should be zoned
separately to controller A or B on the storage subsystem. Furthermore, it is strongly
recommended to use Storage Partitioning when directly connecting to IBM i. Storage Partitioning
is a premium feature on the DS5100 and DS5300 which allows a set of LUNs to be associated
only with specified hosts and host ports. Storage Partitioning allows the creation of multiple host
groups; only the hosts within a particular host group are allowed access to a group of LUNs.
Without that premium feature, all hosts reside in the Default Host Group, which allows IBM i to
access LUNs mapped to other hosts. The recommended approach is to use Storage Partitioning
and create a host group for each IBM i LPAR using the storage subsystem, placing the hosts
associated with that LPAR in the host group. Hosts representing different IBM i LPARs should
not be placed in the same host group, as IBM i does not support shared simultaneous access to
the same LUNs from multiple LPARs.
Note that migrating from IBM i using DS5100 or DS5300 storage through VIOS to IBM i using the
same subsystem directly requires data migration, typically by save and restore. There is no
option to reassign the LUNs from a VIOS host to an IBM i host or use FlashCopy or VolumeCopy.
Performance for IBM i directly attached to DS5100 and DS5300 is very similar to that of the same
adapter and storage configuration attached through VIOS. Direct attachment performance will
not be significantly better than that of VIOS attachment for IBM i. Performance results for IBM i
directly attached to DS5300 are in Chapter 14.5.3 of the Performance Capabilities Reference
manual at: http://www.ibm.com/systems/i/advantages/perfmgmt/resource.html.
40
Advertisement
Table of Contents
