by Liem Nguyen, Director of Communications and Social Media, Dell Storage — May 12, 2010
At EMCWorld, the company announced VPLEX, a set of external, special-purpose hardware appliances that create a heterogeneous storage pool to enable shared access to local and remote SANs and non-disruptive volume migration between them. On his blog, storage analyst Greg Schulz (Twitter @StorageIO) offers a really detailed explanation of VPLEX. Bas Raayman (@BasRaayman) provides some good links for additional reading over on his blog.
A quick glance at available specs tells me it’s not for small or most mid-sized enterprises. VPLEX uses a half or full rack of multi-CPU servers which are inserted between all SANs and servers. An entry level high availability VPLEX system includes total of eight quad-core XEON CPUs, 128GB of cache and 128 8Gb FC ports to connect all front end servers and back end SANs.
The VPLEX software interface comes from EMC’s YottaYotta acquisition and includes a mix of command-line, GUI and custom application tools. You could say there’s a lotta bang for a lotta bucks. This is great news for customers with EMC Symmetrix-sized budgets. However, enterprises facing flat or declining budgets may want to understand the real costs and consider alternatives that are more cost-effective with features and functions that customers will use without adding significant footprint to their data center.
Several folks have pointed out the similarities between VPLEX and Compellent’s Live Volume technology. Both solutions tackle the problem of non-disruptive volume migration, which is very useful in disaster avoidance, load balancing or maintenance situations. The end-user’s storage stays online and the IT department has a lot more flexibility. However the similarities end there as EMC’s VPLEX and Compellent’s Live Volume approach volume migration in entirely different ways.
I sat down with Bob Fine, director of product marketing, to analyze the VPLEX announcement and clarify how it differs from Live Volume. Bob also recaps the difference between Live Volume and VPLEX in this short video clip.
LN: What is the VPLEX Hardware?
BF: VPLEX is a rack mounted hardware system that sits in‑band between heterogeneous storage arrays and servers. A VPLEX system can support one, two or four VPLEX engines. Two VPLEX engines are required for each SAN for high availability. Each VPLEX engine has:
- Two quad-core XEON processors
- 32GB of cache
- 32x 8Gb FC ports
LN: What about cost?
BF: Based on our research, VPLEX starts at about $77,000 for a local-only interconnect system. A high end VPLEX system can scale to over $500,000. These prices do not include the SANs themselves, professional services, the expense of rewiring the data center or the cost of the additional switch ports required for the new high port count devices.
I also wonder about the potential hidden costs because not much is known yet whether VPLEX supports true thin provisioning, RAID6, SSDs, FAST, or other complementary next-generation storage virtualization features.
LN: What are the use cases for VPLEX?
BF: EMC is advocating a high level, “data everywhere and anywhere” storage federation message but the products planned for this year are limited to data center or metro distances. The EMC solution requires multiple high end VPLEX hardware engines and many high bandwidth, low latency network connections. That’s the biggest difference between Compellent and EMC VPLEX. Compellent’s focus is on integrating a software solution that scales. EMC has a significant focus on high-end bandwidth, and all that comes with a hefty price tag. VPLEX uses a great deal of high end hardware to bring several of the Live Volume features to the EMC platform.
LN: Zero downtime maintenance and non-disruptive change management are solid benefits provided by VPLEX. What are the limitations?
BF: VPLEX is not part of the EMC SAN products themselves, but instead is designed as an add-on set of rack mounted servers. VPLEX requires the overhaul of the data center topology and the creation of a new in-between configuration. EMC’s hardware-heavy response is in stark contrast to the Compellent Fluid Data architecture, which enables to non-disruptive data migration to be delivered relatively inexpensively in a software-only configuration. EMC’s technology requires a large complement of dedicated, single-purpose special hardware to deliver the same kind of distributed storage capabilities. Other considerations:
- Requires major hardware investment at each site with one or more high end VPLEX servers for each site plus additional local and remote switch ports
- Major changes to system topology with all SAN and server connections routed through VPLEX
- Write performance decreases with distance and latency
- Conversion of Virtual Machines to VPLEX is not automatic, and requires either additional storage or for the applications to be shut down to complete the process
- Software interface is not integrated with the Clariion software, many features require a command line, others use “AccessAnywhere” or GUI
LN: So what is Compellent Live Volume?
BF: A software feature in the Compellent Storage Center SAN, Live Volume is a virtualized storage application that provides non-disruptive storage migration between SANs in an integrated environment. Live Volume enables on‑demand volume migration, zero downtime maintenance and disaster avoidance capabilities at a fraction of the price of EMC’s VPLEX and requires no hardware, no outages and no system reconfigurations. The Live Volume solution supports any Storage Center configuration or network connections, including iSCSI and Fibre Channel. Live Volume can leverage existing network connections without impact on write performance.
Compellent has made Live Volume to select customers since Q1 of 2010, available with Storage Center 5.1 or later.
Additional features:
- Live Volume is a software-only upgrade and supports all Storage Center models and configurations
- Software is tightly integrated in both Enterprise Manager and the Storage Center GUI
- Asynchronous interconnect is less expensive and enables full performance data writes -- write performance is not dependent on network latency or distance
- Flexible configuration enables unlimited number of Live Volumes between systems, and point-to-point volume migration between more than two data centers
- On-the-fly conversion enables non-disruptive conversion of any volume to a Live Volume—any Compellent system can add Live Volume functionality at any time
Compellent Live Volume
LN: So what’s the starting price for Live Volume?
BF: Live Volume licenses start at under $5,000. As you know, pricing is available from our channel partners and can depend on maintenance and software support options.
LN: Can you summarize Compellent’s point of view on data migration?
BF: From our perspective, data migration capabilities should be built into the architecture itself to reduce complexity, overhead and cost. EMC’s response to Live Volume non-disruptive data migration capabilities further validates Compellent’s vision for a global, shared storage network. The difference is in the implementation. The EMC approach is an external add-on model and is very expensive. The Compellent approach is dramatically more efficient as the core engine is built into the Fluid Data architecture itself.
Comparing CML Live Volume and EMC VPLEX
| Use Cases |
Live Volume |
EMC VPLEX |
| Starting price |
$5,000 |
$77,000 |
| Live volume migration between SANs |
Yes |
Yes |
| Zero downtime maintenace |
Yes |
Yes |
| Disaster avoidance |
Yes |
Yes |
| Volume mobility between 3rd party storage |
No |
Yes |
| Software only architecture |
Yes |
No |
| Integrated software management interface |
Yes |
No |
| Leverages existing data center topology |
Yes |
No |
| Write performance is consistent over distances |
Yes |
No |
| Supports both iSCSI and Fibre Channel interfaces |
Yes |
No |
Additional links: