VMWARE STORAGE PART 4: VSAN

Going through the VMware storage options I would be remiss if I did not talk about VSAN.  VSAN is simply VMware’s next way of helping to further improve the Software Defined Datacenter.  To begin with though, it is important to understand a little about what VMware is trying to accomplish. 2 years ago, on gigaom, an interesting article came through on VMware’s slow and steady attack on storage. This was following the release of their less than stellar Virtual Storage Appliance, VSA. At the time I took exception with this. Of course VMware would never want to get into the storage business, they are a software company. Then came VSAN.

I still do not believe VMware intends to completely own the storage market, but they are certainly changing the game. Now I work for HP, and I remember when server virtualization started to take off, we thought the server was going to become irrelevant, we would just use some cheap whitebox server. Fortunately we at HP realized that we had to step up our game. As usual the server engineering team worked with our alliance partners and built even better products designed around virtualization to give higher virtualization density, and higher performance. I equate this latest storage product to the same thing. It will certainly capture certain market segments, but it is not a threat to the core storage business of the larger storage vendors.

With that said, just what is VSAN? The concept behind VSAN is actually an old one come again. We have been doing scale out object storage for some time in this industry. VSAN simply moves this into the hypervisor stack. The requirements are pretty simple, you need a minimum of 3 host servers running vSphere 5.5 each with an SSD and at least one SAS or SATA drive, HDD. The requirements are well documented so I don’t want to get into those details, but this is enough to get started.

Conceptually, the SSD becomes a cache to accelerate the reads and writes to the drives. The HDDs are used for storage, and replicas are kept based on the rules, generally at least 2 copies of the data on separate hosts.

The setup is pretty simple, and there are hands on labs available online with VMware. It is also quite simple to setup using VMware Workstation running vSphere 5.5 for labs.

This scales currently, in Beta v1, to 8 hosts, so this is not going to be a massive system, more of an SMB environment or a lab system. It also introduces some interesting challenges on the server and network side. On the server, there is pretty limited official support since the raid controller has to enable pass through. There is no raid since this is an object store, data protection is accomplished through multiple copies of the data. On the network side, this is challenging because we are copying data between hosts to retain consistancy. This generally, in my mind, means that the era of running VMware on 1GbE networks is probably nearing an end.

At the end of the day, VMware has a number of use cases. This is a Beta v1 product, I am nervous about running it in production just yet. Many of their use cases are around high performance workloads, VDI for example, where user experience can make or break a project. I do think that this is an exceptional way of creating shared storage in a lab, and gives us many new ways to work in a lab environment.

As to the future of VMware storage, traditional storage, and our industry, I think this is the beginning of the next big thing. I will be discussing HP’s own software defined storage soon, as well as our traditional storage platforms in a VMware context. I don’t see VSAN as a threat, but rather as a call to action on our part to make our products better and continue to innovate. I will personally use VSAN in my lab along side HP StoreVirtual, different use cases, and fun to test.

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VMWARE STORAGE PART 4: VSAN

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