One size does not necessarily fit all…

IBM SAN Volume Controller & HDS USP

It’s been 7 years since IBM released SAN Volume Controller and brought multi-vendor storage virtualization and volume mobility to the mainstream market. SVC provides virtualization in the storage network layer, rather than within a disk system, and IBM has shipped more than 10,000 I/O groups (SVC node pairs).

HDS meanwhile took a different tack. They followed SVC by about 12 months, and have delivered virtualization in the disk system but with the ability to manage external disk systems just as SVC does.

SVC arguably has some advantages in ease of use around data migration, flexible object naming and optimizing performance from external systems (especially when using thin provisioning) but there is no doubt that USP/V and USP/VM are both very solid players in the storage virtualization space.

Both approaches (virtualization-in-the-network and virtualization-in-the-disk-system) are valid. It would be nice to think that one design could address all segments of the market, but it seems to me that each has its sweet spot.

  • Virtualization-in-the-network is a better fit for larger more diverse environments because it’s not dependent on a single box of disks.

This aligns well with IBM SVC’s heterogeneous scalability to 8 Petabytes. By contrast, the HDS USP/V proposition is built around a monolith, so it’s really more of a disk system with benefits.

  • Virtualization-in-the-disk-system is a better fit for smaller environments because its entry configuration is potentially simpler and cheaper.

Smaller environments haven’t been ideally served by either of the leading storage virtualization solutions.

  • HDS USP/VM isn’t really priced for the lower mid-range market and may not have the ease of use demanded by that market segment.
  • IBM’s SVC ‘Entry Edition’ is still network-based and so requires an external disk system which some smaller customers might prefer to avoid at least initially and some smaller customers still complain about the price tag.

This highlights the difficulty of a vendor trying to address multiple market segments with what is essentially still one product.

I’m a fan of getting cool technology like multi-vendor storage virtualization out into the market as broadly as possible, with ease of use and a price that will drive adoption and improve productivity. I’m hoping that as the technology matures, either IBM or HDS will see fit to unleash storage virtualization into the lower midrange at some stage.

Meanwhile as we prepare to press ahead with plans for SVC 6.1 adding new features like Easy Tier, larger and medium-sized customers will continue to be very well served with IBM SAN Volume Controller.


One Response

  1. […] The external virtualization story is very tidy i.e. you can effectively use your v7000 disk system as an SVC. This pretty much covers the simpler, more cost-effective virtualization for smaller customers that I called for in my blog post “One size does not fit all“. […]


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