Dell EqualLogic iSCSI SAN Storage Pricing Performance Virtualisation VMware

Dell EqualLogic is a Virtualised Storage platform which delivers cost savings, exceptional scalability and powerful data management tools on a sensible budget.

Storage is virtualised across all disks in an appliance or group to create a virtual storage 'pool' from which volumes can be delivered. Multiple appliances and disk technologies can be combined to create a tiered storage environment with automated data migration based upon profiling over time.

Why Virtual Storage?

In a traditional storage environment small groups of disks are combined to deliver volumes - for example a pair of disks may be set up as a RAID1 mirror for a system volume, and another group of three at RAID5 for presentation as a data volume. Problems may arise if either of these configurations need to be expanded with time consuming data backup, offline expansion of the array, followed by data restoration often the only option. Even if you can put up with this process, what happens when you run out of space in the storage enclosure? How about if there is some unused space in a group of disks which you'd like to reclaim and deliver to another server? Virtual storage is the answer.

* The number of hot spares is dictated by the RAID level chosen for the appliance. They may actually be located anywhere within the array, for the sake of this diagram they are shown together.

Volumes delivered from a virtual storage pool can be thin provisioned and expanded on the fly which means that you have much greater control over allocation of your storage, in turn it can be optimised to deliver much better value. All of the disks work together to deliver the volumes, which leads to increased performance and reduces 'hot spots' where your most active data resides.

As additional arrays are added the storage pool expands into the new space and volumes are distributed efficiently over time. Each new array introduced not only adds more capacity, it also adds additional processing power and network bandwidth which means that performance scales alongside capacity. This is not so in a traditional 'frame' based SAN where additional disk shelves 'dilute' the resources offered by the limited number of storage controllers or filers. This can lead to degraded performance unless the controllers are significantly over-provisioned from the outset, which in turn leads to additional cost and does not deliver good value whilst you are waiting to 'grow into' your investment.

Storage virtualisation also enables EqualLogic to deliver effective, intelligent snapshotting tools with much greater depth and significantly improved performance when compared with most competiting solutions. Further detail is provided in the SAN Snapshot section of this site.

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