], and fellowIBM blogger BarryW does a great job reviewing the reaction from the media, in hispost [
]. A few questions have popped up from my colleagues, so I thoughtI would take a stab at them here.
- Why now?
This is a reasonable question. Since Invista 2.0 came out months ago in August, and Invista 2.1 is rumored to be out by end of this month, why put out a press release now, rather than just wait a few weeks? Thesignificant part of this announcement was that EMC finally has their first customer reference.To be fair, getting a customer to agree to be a reference is difficult for any vendor. Some non-profitsand government agencies have rules against it, and some corporations just don't want to be bothered byjournalists, or take phone calls from other prospective customers. I suspect EMC wanted to put the good folks from Purdue University in front of the cameras and microphones before they:
- suffer an outage,
- change their minds, and/or
- leave for Winter break
It takes a while for new technologies to get adopted by the marketplace. Geoffrey Moore wrote a book titled [Crossing the Chasm: Marketing and Selling Disruptive Products to Mainstream Customers] that I highly recommend. If you don'thave time to read the entire book, here is a quick [11-page summary] from Parkerhill Technology Group.
In Moore's terminology, Purdue University would be a "technology enthusiast", interested in exploring the technologyof the EMC Invista. Universities by their very nature often see themselves as early adopters, willing to take big risks in hopes to reap big rewards. The chasm happens later, when there are a lot of early adopters, all willing to be reference accounts. The mainstream market--shown here as pragmatists, conservatives, and skeptics-- are unwillingto accept reference claims from early adopters, searching instead for moderate gains from minimal risks. They prefer references from customers that are similar in size and industry. Whether a vendor can get a product to cross this chasm is the focus of the book.
- Why "SAN" virtualization?
Technically, Invista is "storage" virtualization, not "SAN" virtualization. Virtualizationis any technology that makes one set of resources look and feel like a different setof resources, preferably with more desirable characteristics. You can virtualizeservers, SANs, and storage resources.
Here's a quote from Cisco's whitepaper called [Storage Virtualization a Work in Progress]
Virtual SAN (VSAN) technology, supported bythe Cisco MDS 9500 Series Multilayer Director Switch, partitions a single physical SAN into multipleVSANs, allowing different business functions and requirements to share a common physical infrastructure.
How does Invista advance Cisco's VSAN functionality? It doesn't, but that doesn't makethe title a falsehood, or the press release by association full of lies.If you read the entire press release, EMCcorrectly states that Invista is "storage" virtualization. Some storagevirtualization products, like EMC Invista and IBM System Storage SAN Volume Controller (SVC), require a SAN as a platform for which to perform their magic.Marketing people might use the term "SAN" torefer not just the network gear that provides the plumbing, but also to include the storage devices that are attached to the SAN. In that light, theuse of "SAN virtualization" can be understood in the title.
More importantly, it appears that EMC no longer requires that you purchase new SAN equipment from themwith Invista. When the Invista first came out, it cost over a quarter-million US dollars to cover thecost of the intelligent switches, but with the price drop to $100K, I imagine this means theyassume everyone has an appropriately-supported intelligent switch already deployed.
- Why this architecture?
In his post [Storage Virtualization and Invista 2.0], EMC blogger ChuckH does a fair job explaining why EMC went in this direction for Invista, and how it is different thanother storage virtualization products.
Most storage virtualization products are cache-based. The world's first disk storagevirtualization product, the IBM 3850 Mass Storage System, introduced in 1974, and thefirst tape virtualization product, the IBM 3494 Virtual tape Server, introduced in 1997, bothused disk cache in front of tape storage. Later virtualization products, like IBM SVC and HDS USP-V, use DRAM memory cache in front of disk storage, but the concept is the same.People are comfortable with cache-based solutions, because the technology is matureand well proven in the marketplace, and excited and delighted that these can offer the following features in a mixed heterogeneous disk environment:
- improved performance
- instantaneous point-in-time copy
- synchronous mirroring
- asynchronous mirroring
None of these features are provided by Invista, as there is no cache in the switch. Instead,Invista is a "packet cracker"; it cracks open each FCP packet, inspects and modifies the contents, then passes theFCP packet along to the appropriate storage device. This process slows down each read andwrite by some amount, perhaps 20 microseconds. The disadvantage of slowing down every readand write is offset by having other benefits, like non-disruptive data migration.
To compensate for Invista's inability to provide these features,EMC offers a second solution called EMC RecoverPoint, which is an in-band cache-based appliancesimilar in design to SVC, but maps all virtual disks one-to-one to physical disks. It offersremote distance asynchronous mirroring between heterogeneous devices.EMC supports RecoverPoint in front of Invista, but if you are considering buying bothto get the combined set of features, you might as well buy an IBM SVC or HDS USP-V instead,in one system, rather than two, which is much less complicated. IBM SVC and HDS USP-Vhave both "crossed the chasm" having sold thousands of units to every type and size of customer.
Hopefully, this answers the questions you might have about EMC Invista.