One of the more interesting discussions from SFD14 was the review of the various mid-range platforms that Dell EMC now offers. The merger of the two organisations brought Unity and VNX(e) from EMC, while SC (Compellent) and EqualLogic came from the Dell side. Each platform has very different characteristics. Unity and VNX(e) have heritage from the CLARiiON platform (originally Data General), with modifications and enhancements along the way. This included the integration of file services as first-rate citizens. SC comes from Compellent Technologies, an acquisition Dell made after the failed fight with HPE for 3PAR. The Compellent architecture writes new data to fast storage, cascading the inactive blocks to slower (and cheaper) media. EqualLogic was a distributed node architecture, quite different from the other platforms. Again this was an acquisition.
There’s now an all-flash SC platform (as if Dell needs another) which seems to me to be a little pointless. The benefit of SC was in being able to target writes to fast media, while inactive I/O rested on cheaper disk. This also meant optimising for different RAID styles – RAID-1 for write and RAID-5/6 for inactive. With such high performance from flash, there seems little point having two types of media as the marginal saving of RAID-1 can’t be worth the overhead. Perhaps as we see the adoption of QLC NAND, there could be a case made for having different classes of flash. I could also see a scenario where non-volatile flash could play a part. Imagine, for example, using Intel Optane or NVMe flash as the active write area and cascading down to very cheap TLC or QLC. Optane would be a good solution in this case, due to the high endurance of the media compared to flash.
Why retain four platforms? First, there’s history. Bringing two companies together inevitably means overlap. However VNX was supposed to be replaced by Unity; perhaps not yet, but that is on the cards. Kaushik Ghosh, Senior Manager, Product Management with Dell EMC, highlighted during the SFD14 presentations that the two main retained platforms will be SC Series and Unity. This means EqualLogic and VNX will be phased out over time. So now we’re down to two.
Very specifically, Kaushik indicates that both SC and Unity will be retained and invested in, effectively indefinitely, or for the “end of the service life” of the products. The main focus for investments seems to be in bringing the ecosystem around the two products to be more consistent. This means features like CloudIQ will be available on SC. RecoverPoint can be used between platform types. Unisphere will be modified to support SC.
Venn Diagram of Features
Probably the main reason for maintaining two products at this time is the partial overlap of features each platform offers. SC is a block-based system, whereas Unity supports block and file protocols. SC has (post process) de-duplication. Unity doesn’t yet have de-duplication. SC is a federated solution, with features like live migration between arrays. Unity can’t offer federation but is available as a virtual appliance. These characteristics aren’t “planned”, but simply a statement of fact. Both platforms come from different design objectives and development history and now find themselves together in the same portfolio.
The Architect’s View®
Dropping VNX and EqualLogic seems pretty easy. From a marketing perspective only, all-flash SC makes sense. Gartner and others can recognise it as a specific SKU. What about the continuance of two mid-range products? Due to the feature differences, it’s clear at this stage that Dell EMC needs to retain both products. The question is, what happens next? Both SC and VNX/Unity customer groups are no doubt very loyal to their own technology. This is obviously a problem for Dell EMC as a desire to standardise on one platform will be affected by customer sentiment. Of course, neither product is a subset of the other in terms of features.
If I had to place a bet on it, I would say that SC will be modified to be more like Unity, adding file services, de-duplication, Unisphere support and cloud integration. Dell EMC could create an SC VSA if demand was there. As SC offers more Unity features, the inertia of customers to move away from Unity and onto SC can be overcome. With the install base size today, it’s probably worth the engineering effort in the short term.
However, let’s throw in a curveball. Does Dell EMC really want customers to continue to buy traditional arrays, or would they like a transition to HCI and products like ScaleIO? Where the products fit, Ready Nodes or VxRail might work well, replacing ageing storage. Ultimately this agony of choice could be an issue because I don’t see a clear message being given about the boundaries between these platforms.
Are you a customer or reseller? Do you have a better view on specifically how each platform is being marketed? I’d be interested to know.
- Dell EMC Presents Midrange Systems at Storage Field Day 14 (Tech Field Day website, retrieved 6 December 2017)
- Dell EMC Strengthens and Expands All-Flash Midrange Storage… (Dell EMC press release, retrieved 6 December 2017)
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