Test Center: SANs tuned for virtualization pack nice surprises
Compellent, Dell, HP, Pillar Data, and roll-your-own Pillar/DataCore bring strong storage management features to XenServer, VMware, and Hyper-V environments
HP StorageWorks 2000fc G2 Modular Smart Array
The HP is the first storage system I've tested that uses 2.5-inch drives. With the small drives, HP can squeeze 24 disks into a 2U chassis rather than the usual 16 disks into a 3U chassis. The drives included with the test system were 73GB 15,000-rpm SAS drives, for a total capacity of just over 1.5TB formatted, which was priced at $13,000. The system included two 4Gbps Fibre Channel RAID controllers, dual power supplies, and a good basic feature set. It doesn't offer all the features of the more expensive systems, but at $13,000 for a blazing fast system, it offers great performance for the dollars.
Setup of the system was straightforward, with a simple Web-based interface and the features a virtualization administrator would most want to see, particularly snapshots and the ability to clone volumes to create additional VMs. Coalescing multiple snapshots into a single new volume went very quickly, and the overall speed of the system was able to support 16 VMs on a VMware server without bottlenecks.
Pillar Data Systems Axiom 600
The Pillar Data AX600 is not unusual physically, with three components, a management unit (called a Pilot), a controller head (the Slammer), and drive shelves (Bricks), but Pillar Data's approach to storage provisioning and management is definitely unusual. The company calls the approach "application-aware storage," which means that rather than specifying a volume that is RAID5 with a 64KB stripe and scheduled snapshots, you specify an application type -- Oracle Database or SQL Server or VMware ESX hypervisor, for example -- and the system sets up the volume to optimize the performance for that app. A variety of application profiles are included with the system, and more specialized ones are available from the Pillar Data support site.
Rather than specifying a storage tier (SSD, 15K, 10K, SATA), you specify a performance class (premium, high, medium, low, or archive), and the system picks the best storage on which to place the volume, based on what's available. These storage options not only include the speed of the disks the volume is on, but also the place on disk (outer, middle, or inner tracks) and CPU utilization, amount of cache, and allocated bandwidth. The system even includes a predictive analysis module that can analyze the impact on existing storage volumes of a new volume, depending on the performance requirements and application type it is given.
The Pillar Data system was the most expensive of the ones I tested, but it also had the highest capacity, multiple paths throughout for high availability, a very complete feature set, and great usability. Coalescing multiple snapshots into a new image went very quickly, as did mounting the new volume. The system would easily support multiple VMware servers without any storage bottlenecks.
Promise vTrak E610f and DataCore SANMelody 3.0
The build-it-yourself Promise and DataCore system represents how far you can go on a tight budget if you're willing to roll up your sleeves. The Promise vTrak E610f is a 16-drive enclosure that includes two 4Gbps Fibre Channel controllers that offer RAID levels 0, 1, 0+1 (or 10), 5, 6 (double parity drive), 50 (two mirrored RAID 5 volumes), or 60. You can add up to three additional enclosures via Serial Attached SCSI, all using the same dual controllers or as many Fibre Channel dual-controller systems as your switch will support. The Promise system doesn't include drives -- you add your own SAS or SATA drives. Installing drives is straightforward and shouldn't bother anyone with hardware experience; there's even a full paper manual that fully documents the process.
Once the drives are installed, connecting to the system and initializing the RAID set or sets is straightforward. I installed eight Western Digital Raid Edition 500GB SATA drives and eight Seagate Savvio 15,000-rpm 73GB SAS drives, creating a 280GB RAID10 volume with the Savvio drives and a 3.5TB RAID5 volume with the Western Digital drives.