Disk Array Storage: Performance vs. Capacity

As with other areas of IT, disk array storage has changed dramatically in recent years. Just over 20 years ago, personal computers came with huge spinning disks the size of dinner plates with capacities of just a few megabytes. That's right, megabytes. Today, a PC may have a smaller disk encased in a box about the size of a deck of playing cards with a capacity of several hundred gigabytes. Many modern laptops have shed the spinning disk in favor of solid state (flash) storage. Flash storage is far more responsive than spinning disks. However, flash storage is also more expensive and its storage capacities tend to be much smaller than traditional hard disks.

Hard Disk Array StorageAt the enterprise level, the evolution continues. Like consumer PCs, modern networks have traditionally relied on hard disk storage systems. Instead of one disk, these systems consist of arrays of disks. Disk array storage comes with massive capacities measuring in terabytes. Plus, the cost per gigabyte of traditional disk array storage has dropped to attractive levels. However, while capacities have grown and costs have come down, performance has stalled. After all, a disk can only spin so fast.

Hard disk array storage is fine for some environments, but not all. Networks that incorporate virtual desktops and resource-intense applications typically require higher performance storage systems. One alternative to hard disk arrays involves solid state drives (flash storage).

All Flash StorageAll flash storage is an option for enterprise environments that demand high performance storage systems – but it comes with a price. All flash storage systems provide massive performance but they sacrifice capacity. This brings the cost per gigabyte up dramatically. All flash arrays can be cost-prohibitive with staggering costs well into the six figures. Even for companies that can afford the initial expense, an all flash storage array may be overkill for their needs. While some organizations have computing needs requiring the absolute best performance possible, most need a balance between decent performance and affordable storage.

The Best of Both Worlds: Hybrid StorageWith disk storage offering massive capacities at the lowest price per gigabyte and all flash storage offering phenomenal performance at a high price, finding the middle ground could be the best option that balances performance with capacity and cost. Fortunately, hybrid storage systems have been developed.

Hybrid storage systems include both solid state and disk arrays. Commonly accessed files are cached on the super-fast flash drives while less commonly accessed files reside on slower hard disks. This hybrid approach allows for massive storage capacities and performance. Since commonly accessed files are cached on the solid state drives, boot storms are no longer an issue.

Storage vendors offer hybrid storage systems in a variety of configurations. For example, some offer all flash arrays designed to work with existing hard disk arrays. Others offer arrays containing both solid state and hard disk drives. In addition to the physical composition of these hybrid systems, storage vendors also incorporate technologies such as de-duplication and in-line compression. Other technologies such as snapshots and thin replication reduce backups and redundancy while providing business continuity.

Advances in hybrid storage mean that you don't necessarily have to make a choice between performance, capacity, and cost.