Dell's latest firmware release, version 5, for the EqualLogic PS series of iSCSI SANs brings a number of immediate and significant performance benefits to VMware deployments. Some key new features -- including Multipath I/O support and the ability to offload copy operations from hosts to the SAN -- are also supported on Windows with EqualLogic's HIT (Host Integration Tools). Others, such as thin volume cloning and refreshes to the Group Manager and SAN Headquarters administration tools, will benefit all users.
The version 5 firmware also brings dynamic storage tiering to the new Dell EqualLogic PS6010XVS array. (See "InfoWorld review: Dell iSCSI SAN sizzles with SSD, dynamic storage tiering.")
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Unfortunately, the rollout of version 5 wasn't problem-free. The initial 5.0.0 firmware, released a few weeks before VMware ESX 4.1, brought with it some unforeseen problems, generally related to upgrading production systems that were running older code. Three months and two iterations later, the new 5.0.2 version appears truly ready for prime time.
That stumble was quite unlike EqualLogic and may have been caused by the rush to release the firmware ahead of the official unveiling of VMware ESX 4.1. Whatever the case, Dell promises that the problems related to the 5.0.0 and 5.0.1 releases have been resolved. This is good news, as the 5.0.2 firmware offers many reasons to upgrade or to add an EqualLogic array to your infrastructure.
Faster VM copies for VMware hosts
Traditionally, when VMware needed to copy a virtual machine, it treated the storage as a dumb entity and handled the block-by-block copy normally, by reading and writing the blocks to and from the storage array. With the advent of copy offloading, the ESX host can simply instruct the EqualLogic array to copy the blocks containing the image, and the array handles the copy itself.
In real-world tests, this results in a much faster copy operation and a greatly reduced load on the ESX server. In lab tests, this means that cloning a 30GB virtual machine took just over three minutes with copy offloading and more than nine minutes without. During that test, the CPU of the ESX server was pegged, as several virtual machines running on the host had been pushed to their limits. With copy offloading enabled, there was almost no ESX CPU activity required to complete the operation.