This is even more effective than deduplicating data across both disk and SSD because the performance surplus and consistency of latency across all data in an SSD-only solution enables faster inline deduplication and data rehydration than in a hybrid disk and flash system, Forrester said.
There's a big difference between SLC (single-level cell) enterprise-class NAND flash and MLC (mutli-level cell) flash in terms of performance, longevity, and price. SLC NAND stores only one bit of data per cell versus two or three bits per cell in MLC. That translates into SLC having natively higher performance and a lifespan as much as 10 times that of MLC.
Currently, the price for NAND flash in an SSD form factor is about $9 per gigabyte for SLC flash and about $3 per gigabyte for MLC flash. A new class of MLC, called enterprise MLC or eMLC, can withstand up to 30 times more writes than consumer-grade MLC flash technology can, but it also costs about 20 percent more.
By comparison, a Fibre Channel or SAS drives costs 50 to 60 cents per gigabyte.
There are also PCIe NAND flash cards, like those sold by Fusion-io, Texas Memory Systems, Micron, or Virident Systems. Flash cards can be used in all-flash arrays or in application servers themselves. While prices can go through the roof, so does performance -- thanks to the higher speed interconnect and the proximity of the flash storage to the central processors.
Forrester's report focuses on SSD-only options from three vendors: Nimbus Data Systems, Pure Storage, and SolidFire.
While other vendors do offer all-SSD arrays, they don't come with inline deduplication, so they weren't included in the study, according to Forrester analyst and lead report author Andrew Reichman.
According to Forrester, Nimbus offers the broadest protocol support, allowing users to connect to their controllers via Fibre Channel, Gigabit Ethernet or 10GbE iSCSI, CIFS, NFS, or direct InfiniBand.
Recently, eBay rolled out a 100TB Nimbus SSD array to deal with bottleneck issues with its NAS and SAN storage. The Nimbus S-Class array reduced eBay's rack space needs by 50 percent and reduced power use by 78 percent. Most importantly, the SSD's performance reduced the time it takes eBay to bring a new virtual machine online from 45 minutes to five minutes.
The Nimbus architecture is based on two x86-based controllers supporting up to 23 2U (3.5-in high) servers per cluster filled with eMLC flash. The system can hold up to 250TB. Deduplication is optional. Nimbus prices its product on a per-terabyte basis -- it charges $10,000 per usable terabyte.
Pure Storage is also a dual-controller system that scales to 22TB, though the vendor has plans to increase the number of controllers and capacity. Pure Storage is considered a high availability option because its two controllers are active. The system's inline compression and deduplication is always on and works down to a 512-byte chunk size. Based on $5-per-gigabyte retail prices, a 22TB array would retail for $110,000.