IBM Storwize V5020 User Manual (English)

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20 Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.1

Hosts can be Fibre Channel-attached through an existing Fibre Channel network

infrastructure or direct-attached, iSCSI-attached through an existing IP network, or directly

attached through SAS.

1.6.2 Node canister

A node canister provides host interfaces, management interfaces, and SAS interfaces to the

control enclosure. A node canister has the cache memory, the internal storage to store

software and logs, and the processing power to run the IBM Storwize V5000 Gen2

virtualization and management software. A clustered system consists of one or two node

pairs. Each node pair forms one I/O group. I/O groups are explained in 1.6.3, “I/O groups” on

page 20.

One of the nodes within the system, which is known as the

configuration node, manages

configuration activity for the clustered system. If this node fails, the system nominates the

other node to become the configuration node.

1.6.3 I/O groups

Within IBM Storwize V5000 Gen2, one or two pairs of node canisters are known as I/O

groups

. The IBM Storwize V5000 Gen2 supports either two-node or four-node canisters in a

clustered system, which provides either one or two I/O groups, depending on the model. See

Table 1-8 on page 11 for more details.

When a host server performs I/O to one of its volumes, all of the I/Os for a specific volume are

directed to the I/O group. Also, under normal conditions, the I/Os for that specific volume are

always processed by the same node within the I/O group.

When a host server performs I/O to one of its volumes, all of the I/O for that volume is directed

to the I/O group where the volume was defined. Under normal conditions, these I/Os are also

always processed by the same node within that I/O group.

Both nodes of the I/O group act as preferred nodes for their own specific subset of the total

number of volumes that the I/O group presents to the host servers (a maximum of 2,048

volumes for each host). However, both nodes also act as a failover node for the partner node

within the I/O group. Therefore, a node takes over the I/O workload from its partner node

(if required) without affecting the server’s application.

In an IBM Storwize V5000 Gen2 environment (which uses active-active architecture), the I/O

handling for a volume can be managed by both nodes of the I/O group. The I/O groups must

be connected to the SAN so that all hosts can access all nodes. The hosts must use multipath

device drivers to handle this capability.

Up to 256 host server objects can be defined to one-I/O group or 512 host server objects can

be defined in a two-I/O group system. More information about I/O groups is in Chapter 6,

“Volume configuration” on page 287.

Important: The active/active architecture provides the availability to process I/Os for both

controller nodes and allows the application to continue to run smoothly, even if the server

has only one access route or path to the storage controller. This type of architecture

eliminates the path/LUN thrashing that is typical of an active/passive architecture.

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IBM Storwize V5020 Specifications

General

Model	Storwize V5020
Category	Storage
Maximum Number of Drives	240
Form Factor	2U
Supported Protocols	iSCSI
Drive Types Supported	SSD, SAS, NL-SAS
Expansion Units	Up to 9
RAID Levels Supported	0, 1, 5, 6, 10
Host Interface	16 Gb FC, 10 Gb iSCSI
Interface Types	Fibre Channel, Ethernet, SAS
Power Supply	Dual redundant power supplies