Those of you with relatively good memories will remember last year’s announcement from Hitachi/HDS, which at the time promised more than it delivered.  In fact, the anagram posed by Claus Mikkelsen on his blog and used as part of the press release was “REGRADES OUR CLASSY TREATS” and should have translated to “STORAGE ARRAYS CLUSTERED”  my tongue-in-cheek alternative was “A DREARY STORAGE CLUSTER” (who could have imagined such a serendipidous alternative).  With EMC’s new release of VPLEX, it’s deja-vu all over again….

With the usual EMC fanfare, VPLEX has been heralded as “a new storage platform“.  For a product that appears to contain no storage at all (and in fact writes through to the underlying virtualised arrays before confirming I/O to the host), I can’t quite see how the claim stacks up.

Background

OK, before we dive further in, let’s just summarise what VPLEX appears to be about.  In a nutshell, VPLEX offers “federation”, this year’s buzzword for shared or virtualised storage.  The product is currently offered in two flavours; VPLEX-Local, which basically adds a virtualisation layer into the host->fabric->storage stack and VPLEX-Metro, which creates a clustered storage environment, pretty much like the Hitachi HAM (High Availability Manager), announced 12 months ago.  VPLEX-Local is also remarkably similar to IBM’s SVC (SAN Volume Controller).

The Hype Factor

Of course VPLEX is different, or at least that’s what we’re lead to believe.  From the documentation I’ve read, VPLEX-Local is nothing more than a cluster of SVC-like devices.  This functionality is already there in USP V and SVC.

VPLEX-Metro looks slightly different and starts to get interesting.  Multiple VPLEX clusters can be connected together, enabling I/O for a single LUN to be shared across the VPLEX-Metro complex.  Distances of up to 100 miles can be achieved, the only downside being latency overheads.  I’m not aware of SVC offering this kind of functionality, however that is exactly what Hitachi HAM was designed to do.

Catch-up and Future

With the Local and Metro offerings, VPLEX seems to be simply catching up with the opposition.  In true EMC style, however we are being tempted by two future offerings, VPLEX-Geo and VPLEX-Global.

VPLEX-Geo will offer asynchronous federation over a wider distance (presumably infinite, if you’re happy to cope with the latency).  Asynchronous changes offer the possibility for a world of pain for data integrity.  I suspect the first implementations will be tightly controlled using EMC’s own VMware operating system (ESX).  VPLEX-Geo is slated for 2011.

VPLEX-Global is an anything, anywhere offering.  Let’s reserve judgement on that one until we see it – there’s no dated roadmap other than after 2011.

Unanswered Questions

Here’s what I don’t know:

• Will VPLEX pose the same restrictions on the host multipathing as USP-HAM does? HAM requires HDLM.
• Does the host still have to manage their own cluster configuration? (I expect so).
• Is VPLEX-Metro really updating both data copies or is data just being shunted between the clusters, then replicated back again?

And finally, as quoted in the documentation, VMax will offer VPLEX functionality this year, so you may want to consider holding off on that rash VPLEX purchase if you’re on the cusp of moving to VMax.

Final, finally, what happened to InVista?

© Chris for Gestalt IT, 2010. | EMC VPLEX – A Dreary Storage Cluster?
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It has been two days since HDS surprised the enterprise storage world by not announcing a new storage platform to take on the EMC Symmetrix V-Max. Instead, HDS introduced High Availability Manager (“HAM” to us), disappointing some and confusing others. Now that the dust has settled some, it has become clearer just what HAM is and how it works, and we come away more impressed. HDS has taken simple, proven technologies (path management, clustering, synchronous replication) and remixed them into a super-high-availability solution for the largest enterprises. Perhaps this is not what many expected, but it’s certainly a worthwhile addition to the company’s family of products.

HAM combines conventional ingredients to create a whole new flavor

High Availability Manager consists of three main components:

1. A conventional multi-pathing agent like HDLM on each server. This enables the server to continue accessing the storage if one USP fails. It will “think” it’s talking to a single storage target, but will actually be talking to two USPs that can be metro distances (60-100 miles) away, given proper connectivity. Microsoft MPIO will probably be supported as well, and VMware native multi-pathing (NMP) should come shortly after release. Don’t hold your breath for PowerPath to be officially supported in the short term, but it ought to work fine without changes.
2. Existing TrueCopy synchronous storage replication technology will keep the data and quorum disks (see below) in lock-step. This gives the limitation on distance between systems, since latency is the enemy of storage protocol performance. Once the arrays move too far apart, write performance will suffer on the local array while it waits for data to be copied.
3. Conventional clustering technology with a heartbeat and shared quorum disk lets both arrays know what’s going on. The quorum “lives” on the remote side, with that secondary array watching to make sure the primary array is still running. If the heartbeat goes away, the secondary array marks the HAMmed LUNs read/write and starts handling I/O from the servers, which will just have failed over.

So HDS’ secret HAM sauce is ketchup. There’s no amazing new technology here, and maybe that’s for the best in the kind of huge, conservative enterprise environments that will use this product. The big change was in programming the USP controllers to monitor the quorum disk and orchestrate the entire failover. In fact, this might even be considered a feature of TrueCopy, not a standalone product.

HDS ought to reconsider one element of the HAM pitch, however. Although it will undoubtedly yield a very highly-available storage architecture, nothing provides 100% availability. There are many moving parts involved, and unplanned outages can still happen. Multipath driver bugs are not unheard of: Back in the day, one version of a certain three-letter company’s product just plain refused to fail over! An instantaneous outage on one of the host channels or a skipped heartbeat on the USP controllers could also cause a failed failover. Plus, there is no provision for automated fail-back. Once the failover occurs, the system would certainly be operating in a degraded-availability mode and would require a (planned) outage to re-establish operations.

All that being said, HAM remains an attractive offering for shops with multiple USPs visible to critical servers. They can turn on the HAM software with existing hardware and add peace of mind, knowing that everything is that much more available. One aspect that really impresses is the fact that each USP can be running a different firmware, reducing the risk of upgrade-induced outages. Once it ships to customers (in the fourth quarter of this year), we will have to consider the (as-yet unnamed) cost.

And what about the fact that HAM will also allow seamless upgrades to a new generation of USP hardware? HDS still isn’t talking about that possibility!

© Stephen Foskett for Gestalt IT, 2009. | HDS High Availability Manager: How It Works
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HDS telegraphed that a big announcement was coming today. They even made it fun, with a (literally) cryptic blog entry to make sure we were all watching. But the announcement of High Availability Manager, a software product to manage existing HDS USP-V and USP-VM arrays, underwhelmed.

In fact, it’s difficult to tell exactly what High Availability Manager (we’re calling it HAM for now) really is. As noted by our own Chris Evans (USP-V – So Long And Thanks For All The Fish), HAM isn’t the next-generation USP-V with more-granular thin provisioning, automatic storage tiering, and expanded scalability. It isn’t HDS’ answer to the EMC Symmetrix V-Max and it’s forthcoming FAST technology.

So what is HDS up to here? For one thing, they’re not pre-announcing technology that won’t be delivered for some time. HAM appears to be in use at beta customers now, and will no doubt be generally available in short order.

As Storagebod tweeted, “it’s a teaser…the technology to move is part one but you need something to move to. New USP will be part two!”

This Can’t Be All!

Although I have no inside information, it is simple to speculate on what HDS will deliver soon. If I was the product manager for USP-V-II, here’s what I would demand:

1. The next-generation USP-V must be far more scalable than anything we’ve seen yet. This means it must surpass the 8 “engines” and 2,400 drives of the current V-Max from EMC.
2. It must also offer automatic tiering of storage from flash/SSD to Fibre Channel to SATA. In fact, HDS can one-up everyone else (except maybe IBM) by extending tiering to older, external, and even third-party storage arrays. Now that would be something!
3. It must include next-generation datacenter Ethernet support, including 10 Gb FCoE and iSCSI.
4. It must integrate with VMware vSphere and Microsoft Hyper-V, including native multipathing and full API support for snapshots and replication.
5. It must be an easy upgrade from current storage systems, especially USP-V but also third-party arrays.
6. Since it’ll be huge, it must have template-based management for hosts, LUNs, and HA features.

Ham It Up

My fear is that HAM will be used to provide some of these features in a not-exactly-integrated fashion. It will certainly be used for the upgrade path, but let’s hope it’s not the final word for the others. Consider that the “clustering” features of HAM would allow HDS to claim extreme scalability across geographies between multiple USP instances. Although this would not pass the sniff test of many who are hip-deep in enterprise storage, it would likely satisfy the sales-pitch one-upmanship needs when competing with EMC.

On reflection, all of the features mentioned sound exactly like what EMC announced last month! So HDS must have more up their sleeves. Even this USP-II can’t be all HDS has to offer!

© Stephen Foskett for Gestalt IT, 2009. | HDS’ HAM-Fisted Announcement Can’t Be All
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