While at a briefing at HP Discover 2012, the concept of a Flat SAN was introduced to me as a new development to HP’s Virtual Connect. For those new to this technology, VC is a logical construct that sits at the network stack of a BladeSystem converged infrastructure in the form of various modules: FlexFabric (unified ports), FlexFC (fiber channel), Flex10 (Ethernet) and so on. If you want deep dive technical info on Virtual Connect, click here for the HP Virtual Connect Cookbook that contains in depth design scenarios for traditional use cases.

Typically, I’ll see a c7000 BladeSystem chassis with a pair of FlexFabric modules that connect in a northbound fashion to the two fiber channel fabrics. With Flat SAN, HP is promoting the idea that the northbound fabric can be eliminated, connecting the Virtual Connect modules (such as the FlexFabrics I mentioned) directly to an HP 3PAR array.

Simple visual showing a FlexFabric module connected directly to a 3PAR cabinet

According to the discussion I was in, the technology to enable Flat SAN is sitting at the Virtual Connect layer, which I’m inferring to mean will result in various other arrays being compatible down the line (as 3PAR isn’t a fit for everyone, and a lot of legacy storage would prevent the use of this technology). For now, 3PAR is the only array that appears to be supported.

Updated: Entering The Danger Zone … ing

I met up with Alex Kramer, a really sharp engineer with HP, to go over zoning with the new Flat SAN technology in a live environment. It’s always easier to show me something rather than explain it. 😉

While some content is still under CDA, the zoning piece is relatively straight forward. The Virtual Connect modules (which are F_Ports) connect to the 3PAR array (N_Ports). When the blade powers on, VC automatically creates a single initiator / single target zone. There is no cross chatter between other zoned WWNs, no zone sets to activate, and you can still see the flogi details from both VC (in the names section) or on the 3PAR array. Also, the fabric creation on the VC shows a directly connected fabric, instead of the typical SAN fabrics. Most of the VC work is the same as with a traditional SAN, so the learning curve is almost negligible.

Discussing Virtual Connect with HP’s Alex Kramer (picture by Calvin Zito)

If you choose to use WWN pools (and why the heck would you not!) this means you can simply pre-populate the WWN pool IDs into the 3PAR array to present the storage volumes and are good to go (no manual zoning work at all). Pretty cool stuff!

Thoughts

The Flat SAN concept seems like a direct, competitive move against Cisco UCS, which uses a pair of fabric interconnects to reduce a significant amount of chassis level networking infrastructure today. Cisco made the decision to build a chassis with a pair of fabric extension (FEX), such as the 2208 module, and connect them to a pair of intelligence fabric interconnects like the 6248. HP is making the reverse move and keeping switching intelligence at the chassis level (with Virtual Connect and FlexFabric) and instead removing the SAN.

If 3PAR storage were a good fit for the design, this seems like a strong argument for a less complex, and possibly less costly, solution (HP claims 86% less components, 2.5X faster provisioning, and 55% less latency). For more details, I encourage you to head on over to Calvin Zito’s post on the matter: More on Virtual Connect with 3PAR with Flat SAN technology.

Either way, it’s very interesting to imagine a BladeSystem environment without a SAN. Who really likes zoning, anyway? Let me know what your thoughts on this are! 🙂