EMC VFCache respinning SSD and intelligent caching (Part I)

This is the first part of a two part series covering EMC VFCache, you can read the second part here.

EMC formerly announced VFCache (aka Project Lightning) an IO accelerator product that comprises a PCIe nand flash card (aka Solid State Device or SSD) and intelligent cache management software. In addition EMC is also talking about the next phase of the flash business unit and project Thunder. The approach EMC is taking with vFCache should not be a surprise given their history of starting out with memory and SSD evolving it into an intelligent cache optimized storage solution.

Data center and storage IO performance capacity gap (Courtesy of Cloud and Virtual Data Storage Networking (CRC Press))

Could we see the future of where EMC will take VFCache along with other possible solutions already being hinted at by the EMC flash business unit by looking where they have been already?

Likewise by looking at the past can we see the future or how VFCache and sibling product solutions could evolve?

After all, EMC is no stranger to caching with both nand flash SSD (e.g. FLASH CACHE, FAST and SSD drives) along with DRAM based across their product portfolio not too mention being a core part of their company founding products that evolved into HDDs and more recent nand flash SSDs among others.

Industry trends and perspectives

Unlike others who also offer PCIe SSD cards such as FusionIO with a focus on eliminating SANs or other storage (read their marketing), EMC not surprisingly is marching to a different beat. The beat EMC is marching too or perhaps leading by example for others to follow is that of going mainstream and using PCIe SSD cards as a cache to compliment theirs as well as other vendors storage systems vs. replacing them. This is similar to what EMC and other mainstream storage vendors have done in the past such as with SSD drives being used as flash cache extension on CLARiiON or VNX based systems as well as target or storage tier.

Various SSD locations, types, packaging and usage scenario options

Other vendors including IBM, NetApp and Oracle among others have also leveraged various packaging options of Single Level Cell (SLC) or Multi Level Cell (MLC) flash as caches in the past. A different example of SSD being used as a cache is the Seagate Momentus XT which is a desktop, workstation consumer type device. Seagate has shipped over a million of the Momentus XT which use SLC flash as a cache to compliment and enhance the integrated HDD performance (a 750GB with 8GB SLC memory is in the laptop Im using to type this with).

One of the premises of solutions such as those mentioned above for caching is to discuss changing data access patterns and life cycles shown in the figure below.

Evolving data access patterns and life cycles (more retention and reads)

Put a different way, instead of focusing on just big data or corner case (granted some of those are quite large) or ultra large cloud scale out solutions, EMC with VFCache is also addressing their core business which includes little data. What will be interesting to watch and listen too is how some vendors will start to jump up and down saying that they have done or enabling what EMC is announcing for some time. In some cases those vendors will be rightfully doing and making noise on something that they should have made noise about before.

EMC is bringing the SSD message to the mainstream business and storage marketplace showing how it is a compliment to, vs. a replacement of existing storage systems. By doing so, they will show how to spread the cost of SSD out across a larger storage capacity footprint boosting the effectiveness and productive of those systems. This means that customers who install the VFCache product can accelerate the performance of both their existing EMC as well as storage systems from other vendors preserving their technology along with people skills investment.

Key points of VFCache

Combines PCIe SLC nand flash card (300GB) with intelligent caching management software driver for use in virtualized and traditional servers
Making SSD complimentary to existing installed block based disk (and or SSD) storage systems to increase their effectiveness
Providing investment protection while boosting productivity of existing EMC and third party storage in customer sites
Brings caching closer to the application where the data is accessed while leverage larger scale direct attached and SAN block storage
Focusing message for SSD back on to little data as well as big data for mainstream broad customer adoption scenarios
Leveraging benefit and strength of SSD as a read cache and scalable of underlying downstream disk for data storage
Reducing concerns around SSD endurance or duty cycle wear and tear by using as a read cache
Off loads underlying storage systems from some read requests enabling them to do more work for other servers

Ok, nuff said for now, I think I see some storm clouds rolling in…

Cheers gs

Greg Schulz – Author Cloud and Virtual Data Storage Networking (CRC Press, 2011), The Green and Virtual Data Center (CRC Press, 2009), and Resilient Storage Networks (Elsevier, 2004)

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