InfoWorld review: Dell EqualLogic iSCSI SAN kicks it to 10G

Dell's EqualLogic PS6010XV 10G iSCSI array delivers big time performance, offering an easier and lower cost option to Fibre Channel

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The controllers in the PS6010XV are truly redundant. Although there are four 10G ports between them, only two are active at any one time. Should an interface or controller fail, the redundant controller will immediately and seamlessly take over. In fact, it's even possible to upgrade the controller's firmware on the fly with no downtime. The passive controller is upgraded, then takes charge as the primary controller is updated, allowing the process to complete without losing a packet.

It's this type of enterprise feature that can make a huge difference in data center operations, especially storage functions. It's never a good time when dozens and dozens of servers need to be powered down in order to upgrade the back-end storage.

Beyond gigabit throughput
The lab setup for the PS6010XV was fairly simple: a Dell PowerEdge R710 server with 96GB of RAM and two Intel Xeon X5590 CPUs, a dual-port Intel 10G interface card, and a Dell PowerConnect 8024 24-port 10G switch in the middle. The R710 ran Windows Server 2008 R2 Datacenter, as well as VMware ESX 4 and CentOS 5.4 for a variety of tests. The PS6010XV was equipped with 16 600GB 15K SAS drives in a RAID 10 array (price as tested, $68,200).

Overall, the performance surpassed that of EqualLogic's gigabit-based arrays, easily eclipsing gigabit throughput during streamed reads and pushing over 200MBps when pulling directly from the controller cache in a 32K streaming read test, while a closer raw read beyond the cache pulled in around 160MBps. Write performance was necessarily lower, but still came in at 130MBps on a 32K streaming write test. The random access times were an impressive 2.8ms, with a streaming access time of 1.84ms. Some other highlights were the 26,000 IOps reached during a 2K streaming read at 50MBps and a 182MBps transfer rate on a 256K 50/50 random read/write test. There's no doubt this is a fast array, helped considerably by the oodles of cache.

Like any array, the PS6010XV is quite dependent on a battery-backed write cache. Disabling that cache leads to significantly reduced write speeds, so it's important to ensure that your workload doesn't push that cache beyond its limits. There's a total of 4GB of cache in the array, and that's a large part of the overall performance.

The array can support RAID 5, 6, 10, and 50, and the RAID levels can be configured on a per-array basis. The functional RAID level can be modified later on the fly, but only in certain circumstances. For instance, you can convert from a RAID 50 to a RAID 5 or 6, but not to a RAID 10.

The PS6010XV can also support up to 512 snapshots per volume, or up to 10,000 total snapshots, which should be more than enough for any implementation. Snapshots are configured on a per-volume basis and can be scheduled directly from the management interface.

SAN Headquarters
The one thing missing from the Dell EqualLogic Group Manager is performance information. There's no facility to monitor array or group performance. However, Dell has a companion tool called Dell EqualLogic SAN Headquarters that closes that gap.

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