Clariion array update blurs line between EMC platforms
A bigger, faster Clariion with advanced features, which first appeared in the Symmetrix line, has industry observers wondering about the increasing overlap between EMC systems.
As expected, EMC today rolled out its CX4-120, CX4-240, CX4-480 and CX4-960 systems. The CX4 platform brings features, such as solid-state disk (SSD), virtual provisioning and disk spin-down, which are already featured in Symmetrix and other EMC systems, into the midrange Clariion.
The Clariion CX4 platform scales to 960 drives, 32 GB cache and 32 front-end ports. With 1 TB disks, a total raw capacity of 960 TB isn't far below the 1 PB listed maximum raw capacity of the Symmetrix. The low-end Symmetrix configuration, the DMX-800, holds 96 drives, which is fewer than the smallest CX4.
Some features in the Clariion CX4 also overlap with those of the Celerra NAS family, prompting speculation that EMC may be quietly laying the groundwork for merging some of its disk arrays down the road.
But according to Barry Ader, EMC's senior director of storage product marketing, EMC has no plans for consolidating platforms. "We got the same question when we came out with the CX3," he said. "Capacity is just one piece of the overall package. Symmetrix has a very different architecture from Clariion."
Symmetrix has a multicontroller, high-availability architecture, more flexible cache options and can hold more cache (up to 512 GB) than the new Clariion CX4-960 (up to 32 GB). It also supports mainframe connectivity, while Clariion is for open systems.
However, recent Clariion refreshes have added features that were previously exclusive to Symmetrix, such as active-active controllers and quality of service controls. Today's release adds persistent write cache to Clariion, as well as a boost in high-performance, Tier 0 capacity with support for SSDs coming to the CX4-960 in October.
"Clariion does run at five 9s [of availability]," Ader said. "But Symmetrix's dynamic cache controls allow high-end customers to meet performance requirements in multiple ways -- it's at a different level from Clariion's quality of service."
Asked if there was anything architecturally preventing Clariion from getting similar fine-grained cache controls over time, Ader responded, "I don't' have an architectural answer for that right now."
EMC has also given the Clariion CX-4 line its own embedded replication software in the form of a RecoverPoint splitter that allows customers to manage EMC's heterogeneous asynchronous replication without a separate network device. Users will still need MirrorView if they want synchronous replication.
Users welcome more capacity, mull Clariion vs. Symmetrix
While the highest of high-end shops won't replace Symmetrix with Clariion anytime soon, the CX4 may postpone a move to the more expensive DMX for some rapidly growing midrange shops.
David Dulek, storage administration lead for Fastenal Company Purchasing, said a new disk array is not in his current plans but would probably go with a CX4 for his next storage expansion. "I'd like to go with a DMX for the performance," he said. "The price/performance isn't quite there for me yet, though. The acquisition cost is too high."
That's the common perception among midrange shops, Dulek said. "No one can afford DMX, though the average life of a DMX is two to three times greater than Clariion. The Clariion only lasts between three and five years, while there are still Symmetrix arrays running from the late 90s," he said.
Charles Shepard, director of systems architecture for EMC customer MGM Mirage, said he's looking to the CX4 to boost disk and cache capacity over his "maxed-out" CX700. "Looks like EMC has finally realized the potential of the Clariion platform and its flexibility," he said. "This is a gap-filler and tier-extender all in one."
Though CX4 doubles capacity of the CX3 line, customers said they could need even more capacity down the road. "We actually have an Exchange 2007 project coming up, and we are contemplating giving 500 MB to 2 GB mailboxes to every one of our 16,000 active users," said Michael Passe, storage architect for Beth Israel-Deaconess Hospital in Boston. "I will need the [maximum] number of drives these new arrays can handle just to get that much capacity."
Multiprotocol, backup use cases also overlap
Another customer said he was unsure whether to go with a CX4 or EMC's Celerra multiprotocol NAS platform, which already has virtual provisioning (EMC's term for thin provisioning). "What we have been looking at is what EMC refers to as their Unified Storage platform using [the] Celerra product," said Michael Biedermann, systems analyst at the University of New Mexico Hospital. "[It] would give us options to use NAS or Fibre Channel SAN on the same array, allowing us to use any combination of iSCSI or Fibre Channel protocols. I'm not sure if CX4 will integrate a lot of the feature sets that Celerra brings to the table."
The CX4's new spin-down feature, while not available until 2009, is being positioned for "appropriate application workloads like backup to disk [and] disk-based archiving," according to EMC. However, spin-down is already available for the EMC Disk Library backup system based on Clariion hardware. EMC needs time to test and qualify CX4 spin-down, Ader said.
"We have tested and qualified [spin-down] with our own backup technologies, such as the EMC Disk Library," Ader said. "But for broader backup to disk applications, we will be exposing the right level of API to other more general backup applications."
EMC's spin-down will be managed differently from the MAID technology that Copan pioneered in its high-density archival boxes, Ader said, noting that while Copan's array only allows 25% of the disks to be spun up at a given time, the CX4 will be able to spin up 100% of its disks at once.
