5 Best Practices for iSCSI in a Virtual Server Environment

In the last 10 years, there has been much discussion and debate around iSCSI SANs (storage-area network), but iSCSI has finally served as a network storage for virtual server environments. The cornerstone stood firm, the analyst said.

Enterprise data storage vendors like HP's LeftHand network and Dell's EqualLogic have told some customers that the overhead of network storage is an obstacle to server virtualization, and they say they are ready to use iSCSI. Features and advertises the lower price of iSCSI SANs relative to optical channels. But Jeff Boles, senior analyst and director of the validation services division at Taneja Group in Hopkinton, Mass., believes there are some technical reasons why iSCSI is more attractive to virtual servers.

"A lot of optical channel research is based on the assumption that a port has only one host," Boles said. "iSCSI also virtualizes access over IP connections, and it also has multiple host connections and multiple queue modes. Related Capabilities."

Although the basic best practices for iSCSI SANs are now well known, if you are thinking of using iSCSI SANs to support server virtualization, experts say that except when through iSCSI connections Beyond the server, there are still some different factors to consider. Here are 5 best practices for using iSCSI in a virtual server environment.

Best Practice 1: Looks Farther Than Basic iSCSI

In the years when iSCSI just appeared, the product has time to mature and develop, and constantly in the process of development. Add personalized features. At the same time, the proliferation of iSCSI-related products makes software-based iSCSI initiators and targets available for free. iSCSI SANs can also be built using general purpose server hardware and open source software.

But Boles said that iSCSI experts like HP's LeftHand and Dell's EqualLogic charge a high price for advanced features like integrated VMware snapshots. Other iSCSI SAN vendors, such as EMC and NetApp, offer unified storage products with a wide variety of server connections, including iSCSI. Disk arrays from storage vendors also provide features such as quality of service and a management console that senses virtual machines.

These arrays connected to the iSCSI network can have a big impact, Boles said. "If you have the right infrastructure, such as a well-established, fully managed Cisco environment, you can Virtual servers implement more complex and detailed strategies."

On the other hand, according to Greg Schulz, founder and analyst of StorageIO Group in Stillwater, Minnesota, some advanced iSCSI for virtual server environments Implementations are not required because the first considerations in a virtual server environment are cost and integration. With the growth of data and the gradual emergence of 10Gb Ethernet, some industry experts believe that technologies such as TCP/IP offload engines (TOE) will continue to enter people's field of vision.

But users need to make a trade-off between these performance improvements and their original intentions, Schulz said, "If I implement iSCSI because of its low cost, I probably won't invest in hardware interface cards. As an alternative, I might want to implement jumbo frames and QoS functionality in software.”

Best Practice 2: Consider where iSCSI targets should exist in the virtual environment on a per-application basis
< For VMware environments, Schulz said that between VMware's clustered file system (VMware vStorage VMFS) and raw device mapping (RDM), "previously users had to make a tough choice." Prior to version 3.5, VMFS provided features similar to VMotion, but sometimes RDM was the only way to continue to use the value-added features of storage arrays such as snapshots and virtual configuration.

But now the situation is different, Brian Garrett, vice president of ESG labs at Enterprise Strategy Group (ESG) in Milford, Mass., says users should still assess where to place them in the infrastructure for performance and manageability. iSCSI target. They can choose to place the target in the form of a virtual disk at the hypervisor level, let the server virtualization software handle the call to the background storage through the virtual disk layer, or deploy the target on the disk array to provide a certain degree of faster storage for the background. Block access.

"The decision depends in part on which way you're used to," Garrett said. "But block-based applications like SQL databases and raw disks work fine and may be better suited for pass-through or native mode.

Best Practice 3: Rethinking Network and Cabling Design

"One problem that users often overlook is how iSCSI frees you from the old model," Taneja Group Boles said. Storage professionals are accustomed to the world of optical channels, with a single disk array connected to servers located on different aisles in the data center through a series of complex switches and cables.

With the expansion of the iSCSI SAN architecture based on general-purpose hardware, Boles said that the implementation of a new network storage may also be an opportunity to rethink the data center layout. "With some of these iSCSI systems, you can distribute storage and server farms at intervals, making storage closer to the server environment without the need for such long cables."

Rethinking the physical resource placement of the data center can help solve problems It does not overload some parts of the network. He added, “You don’t have to drastically reduce I/O and then fan the entire infrastructure—the staggered distribution avoids these bottlenecks.”

Best Practice 4: Watch for Monitoring

Both Boles and Garrett emphasize that the new virtual world needs new monitoring tools that support virtualization in every part of the data center, especially when A highly mobile virtual machine moves around the network. “When you enter the virtual environment, performance monitoring and tuning becomes even more important,” said Garrett of ESG Labs. "In the physical world, you can more easily ensure that you have the right number of actuators to avoid over-integration and violate basic storage guidelines."

Taneja Group's Boles adds: "Compared to returning to use Monitoring tools to renovate the network will be much simpler to implement from day one; remember this when making purchasing decisions.”

Best Practice 5:10 Gigabit Ethernet is still far away

The next boost in Ethernet bandwidth may improve iSCSI performance and provide more opportunities to centralize the network in the data center, and the transition to 10 Gigabit Ethernet will begin soon, according to IDC, Framingham, MA Rick Villars, vice president of storage systems and executive strategy, said, "This year will be a year for server vendors to tell people to use 10 Gigabit Ethernet."

But Villars reminds everyone to be careful not to prematurely turn an iSCSI SAN into a 10GbE network, especially if you are dealing with a virtual server environment. "You have to decide if iSCSI is the first or last to upgrade (to the new 10GbE network)," Villars said. "Because it's still in its infancy, you don't want to implement it now (on a 10GbE network). iSCSI."