IBM System Storage DS3500 Introduction And Implementation Manual page 672

AIX.fm
disk. Because of this, a failure of a single disk will only impact the single client partition using
that disk.
If using SAN storage, the Virtual I/O Server can use a LUN for the storage backing device.
The SAN environment can be used to provision and allocate LUNs, and the Virtual I/O Server
can map the LUN to a virtual disk as though it were a physical disk. If the LUN is configured
with RAID, the disk being presented to the client partition is RAID protected by the SAN
storage. If the client partitions require data protection, using a LUN configured as a RAID
array can be an effective solution. It is preferred to map SAN-attached LUNs as physical
volume backing storage rather then configuring volume groups and logical volumes on top of
them.
If using the Integrated Virtualization Manager instead of the Hardware Management Console,
the concept of logical volumes is replaced with storage pools. Like logical volumes, the
storage pools can subdivide physical disks and present them to different clients as virtual
disks. This technology can be used in entry-level server environments or in BladeCenter
environments.
Planning for dual Virtual I/O Servers
VIO1
FC protocol driver (fscsi0)
FC Adapter (fcs0)
Figure 21-2 Dual VIO Configuration with MPIO
The Figure 21-2 shows the recommended scenario for dual Virtual I/O Server solution. This
configuration provides multiple paths to the data at the client partition as well as at the Virtual
I/O Server. In addition, two SAN switches are included in the configuration to provide
redundancy in the SAN.
Although this configuration illustrates the virtualization of a single client disk, it can be
extended to multiple disks if required. Each Virtual I/O Server uses multiple paths to the SAN
LUNs through two host bus adapters, each connected to a different SAN switch. This allows
the Virtual I/O Server to reach the data if one of the SAN switches fail. The SAN LUNs are
treated as physical volumes and are mapped to two different virtual SCSI adapters to support
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IBM System Storage DS3500: Introduction and Implementation Guide
Client Partition
Virtual SCSI Disk Drive (hdisk0)
vSCSI Client adapter (vscsi0)
vSCSI Server adapter (vhost0)
MPIO FC SCSI Disk Drive (hdisk0)
MPIO
FC protocol driver (fscsi1)
FC Adapter (fcs1)
SAN Switch
Controller A (dac0)
DS3500 (dar0)
Draft Document for Review March 28, 2011 12:24 pm
MPIO
vSCSI Client adapter (vscsi1)
vSCSI Server adapter (vhost0)
MPIO FC SCSI Disk Drive (hdisk0)
MPIO
FC protocol driver (fscsi0)
FC Adapter (fcs0)
SAN Switch
Controller B (dac1)
Logical Drive
VIO2
FC protocol driver (fscsi1)
FC Adapter (fcs1)