IBM’s Scale-out FlashSystem Solution

IBM’s Flash strategy is a two-pronged approach, targeting the two segments that IDC labels as:

1. Absolute Performance Flash
2. Enterprise Flash

Last week I outlined the new FlashSystem 840 and focused mainly on the Absolute Performance aspect. Absolute Performance for IBM means latencies down around 95 microseconds write and 135 microseconds read, whereas most Flash storage systems in the market are talking 500+ microseconds best case. I’m guessing that in the new world of I/O bound applications, having 3 or 4 times the latency overhead could be a real problem for those vendors at some stage.

This week however I’d like to focus on the Enterprise Flash market segment.

Enterprise Flash

When we and IDC talk about Enterprise we are more concerned with the software stack and how it is used to address issues of:

• Scalability
• Snapshots & Clones
• Replication
• Storage Efficiency
• Interoperability

The short answer to all of these is IBM’s SAN Volume Controller. Folks who are not very familiar with SVC often assume that SVC adds latency to storage. In the case of spinning disk systems, my experience has been that SVC reduces latency (due to intelligent caching effects) but takes about 5% of the top of maximum native IOPS. In the real world that means that things will almost always go faster with SVC than without it.

Scale-out Flash Latency

In the case of Flash, the picture is slightly different. The latencies of the FlashSystem 840 are so low that SVC caching does not fully compensate for other effects and the nett is that putting SVC in front of your FlashSystem 840 is likely to add around 100 micro-seconds of latency.

Yes that’s right, only 100 micro-seconds. I should add that I have not personally verified this, but have been told that is what we are seeing in IBM’s internal lab tests.

When you add 100 micro-seconds to the low latency of the FlashSystem 840 (95 microseconds write, 135 microseconds read) you still have numbers down below 250 microseconds, which is twice as fast as the numbers quoted on products like XtremIO and Violin 6200.

Even way back in 2008 we announced a benchmark result of 1 million IOPS with SVC and Flash, code-named Quicksilver. At the time the IBM statement said that IBM was planning a complete end-to-end systems approach to Flash and…

“Performance improvements of this magnitude can have profound implications for business, allowing two to three times the work to [be completed] in a given time frame for . . . time-sensitive applications like reservations systems, and financial program trading systems, and creating opportunity for entirely new insights in information-warehouses and analytics solutions”

So this is not new for IBM. The recently announced FlashSystem Solution with SVC is the culmination of six years of preparation (including SVC tuning) by IBM.

Full Enterprise Software Function Set

So you can understand now why IBM does not need to reinvent a whole separate scale-out offering of the sort that Whiptail Invicta (Cisco’s new EMC killer) and XtremIO Cluster (EMC’s new fat-boy SSD system) have tried to create. IBM can deliver a much more mature and feature-rich solution with consistent management and feature functions right across the board from the small V3700 with Easy Tier Flash right through to high-end SVC Flash Solutions like the one implemented by Sprint in 2013.

An Elegant Scale-Out Flash Solution

SVC brings proven data center credentials to scale-out Flash, delivering the full Storwize software stack while adding as little as 100 microseconds of latency. That is a good story and one that will not be easily matched by any competitor, and if the market would prefer something that is more tightly coupled from a hardware point of view then I don’t see why IBM couldn’t also deliver that in future if it wanted to.

So IBM has avoided the need to reinvent, develop, or buy-in a new immature scale-out mechanism for Flash. By using SVC you get FlashCopy snapshots and clones, as well as volume replication over IP, and Real-time Compression. But possibly most important of all is the full SVC interoperability matrix. How’s that for a software defined storage strategy that delivers rapid time-to-value in exactly the way it’s meant to.

For more info you can check out the IBM FlashSystem product page and the IBM Redbook Solution Guide “Implementing FlashSystem 840 with SAN Volume Controller”