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IT organizations are recognizing the benefits of virtualizing their datacenters, and many of them are enabling server virtualization with VMware Infrastructure 3. VMware Infrastructure 3 allows IT organizations to manage their server infra-structure as a single pool of resources on which applications can be deployed and then moved dynamically from server to server as workload and business requirements dictate (Figure 1). Some VMware Infrastructure 3 features, including High Availability (HA), VMotion, and the Distributed Resource Scheduler (DRS) require shared storage.
With applications and their host operating systems encapsulated into individual virtual machines, they are no longer bound to a specific physical server. IT organizations can finally break free of the legacy of silo-oriented applications that limit sharing and require each application to run on its own dedicated set of underutilized hardware. By virtualizing and consolidating their applications onto a smaller number of more highly utilized physical servers, organizations can re-claim valuable datacenter space and reduce their power and cooling requirements. With applications and servers decoupled, they are free to allocate resources to applications as their workloads change and as their business priorities dictate. Rolling out new applications does not always require deploying new servers because they can draw on the power of a shared infrastructure.
VMware Infrastructure 3 offers compelling features for IT organizations concerned with resource management, high availability, and disaster recovery. VMware VMotion enables running virtual machines to move from server to server. This allows administrators to balance workloads and performance to match user demands, and even to vacate a server in order to take it offline for maintenance. VMware HA monitors the state of running virtual machines and, in the event of a server failure, restarts the virtual machines on alternate servers.
A Choice of SAN Technologies
Features such as VMotion and VMware HA require continuous access to the underlying storage from multiple servers, which requires implementing a shared storage infrastructure. VMware allows customers to choose between traditional Fibre Channelbased SANs, network-attached storage, and iSCSI SANs. There are several advantages to using iSCSI SANs implemented with the SAN/iQ® platform from LeftHand Networks.
SANs based on LeftHand’s SAN/iQ platform use simple and cost-effective technology that helps IT organizations save on the cost of implementing storage-specific networks with specialty host bus adaptors, switches, and optical interconnects. In addition, LeftHand SAN/iQ provides specific features that virtualize storage in ways that are analogous how VMware virtualizes server resources (Figure 2).
LeftHand SAN/iQ products use standard IP networking, a technology that every IT organization understands and has existing infrastructure to support. Ethernet networks are everywhere, so equipment to support them is priced low by a highly competitive marketplace. This significantly reduces the cost of iSCSI SANs. The SAN/iQ platform allows IT organizations to add storage as needed, incorporating new modules in its clusters dynamically and transparently.
Capabilities Analogous to VMware
LeftHand’s SAN/iQ platform is certified to work with VMware, and is listed on VMware’s Storage/SAN Compatibility Guide for ESX Server 3.x. In addition, several SAN/iQ platform features complement VMware’s virtualization capabilities by performing functions in storage that are analogous to those VMware performs in servers:
- Organizations can clone storage volumes just as VMware clones virtual machines. But by cloning at the storage level, duplicate volumes can be created through snapshot mechanisms and mounted for read/write activity in an instant and with minimal use of storage.
- Just as VMotion can move running virtual machines from server to server, the SAN/iQ platform can move virtual disks from storage cluster to storage cluster without taking down or reconfiguring the virtual machine. This allows logical volumes to be moved to different storage clusters to balance storage capacity and workloads, and it can be used to completely offload a cluster so that it can be taken out of service for upgrade or maintenance.
- The SAN/iQ platform allows IT organizations to treat their storage infrastructure as a single, continuously available, virtual pool of storage.
You even can distribute the pool of storage among multiple locations, ensuring that the SAN/iQ platform’s built-in replication function maintains identical copies in each of two locations. VMware can re-start failed virtual machines in alternate locations even through the failure of a datacenter that takes one site’s servers and storage offline.
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