Guidelines for virtualising storage infrastructure

Virtualisation is showing up in all layers of the storage infrastructure. However, there's still some confusion on where to embed virtualisation and when to use it. This all depends on the size of the storage infrastructure, the type of applications running in it, and the levels of control and visibility required by administrators.

Storage managers need to balance the benefits of virtualisation against the complexity it brings. Let's take a look at some guidelines for implementing virtualisation in your storage infrastructure:

1. Match the intelligence of your Fibre Channel (FC) storage-area network (SAN) infrastructure to your levels of server and storage virtualisation.

Using VMware's VMotion, virtual servers may move to different server hardware. But as servers move, so do their virtual initiators and targets. FC SAN switches need to recognize these changes so server multipathing and provisioning continue to function across the FC SAN when moves occur. Otherwise, administrators will need to manually make zoning and logical unit number (LUN) masking changes.

2. Partitioning should be available and configurable at all layers.

Partitioning assigns each layer of storage virtualisation its own administrators, memory, network bandwidth and processing power. Partitioning helps prevent secondary applications from consuming physical resources needed by mission-critical production applications. Administrators can also make changes for test applications in one partition without the changes impacting production applications in another partition.

3. Virtualize performance-intensive application servers cautiously.

Sometimes less virtualisation is better when virtualizing performance-intensive applications. Too much virtualisation can make it difficult for administrators to quickly diagnose the underlying resources used by the application. Before virtualizing, administrators should verify that storage resource management (SRM) software can integrate with the specific storage virtualisation software.

4. Virtualize servers and storage with low performance and utilisation first.

Servers with low performance and storage utilisation are those most likely to provide the highest return on your virtualisation investment and to require the least amount of management. Consider virtualizing these servers using iSCSI SANs, as they can take advantage of some of the virtualisation benefits inherently provided by TCP/IP.

Vendors are moving closer toward tying their storage virtualisation and SRM software together. But because of the time and effort required to implement virtualisation and complementary SRM software, you should deploy virtualisation products gradually while keeping expectations at a modest level.