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Pondering VPLEX and backup

The Twittersphere was abuzz yesterday with EMC’s announcement of VPLEX. For those of you who missed it, VPLEX is a storage virtualization and caching solution that presents block storage over long distances. The initial release only supports data center and metro distances with a future of continental and global reach. The announcement struck me as yet another flavor of storage virtualization which is already offered by many vendors, and got me thinking about protecting VPLEX data.

Traditional data protection architectures revolve around the concept of a master backup server supporting slave media servers and clients. The master server owns the entire backup environment and tells each server when and where to backup. The model is mature and works well in today’s datacenters where servers are static and technologies like VMotion move VM’s to new servers within the confines of the datacenter. However, the concept of global VMotion can break this model.

Now, let’s turn the discussion to VPLEX which theoretical allows you to move virtual machines freely. You can imagine a scenario where your Exchange VM is in Boston today and then is moved to San Diego tonight. That might be nice from a computing and storage standpoint, but what about backup? You have moved the system over 2500 miles and now have to protect it. Do you push the data back to Boston which could consume large amounts of bandwidth or use an alternative backup infrastructure in San Diego? If the latter, you will have to reconfigure the Exchange server backups to point to San Diego’s backup server, but what if you move it back to Boston in a week? One option is to maintain a duplicate Exchange VM in Boston, but how do you put both Exchange VM’s (Boston and San Diego) into hot backup mode simultaneously? (e.g. Instantly quiesce both servers to ensure that data is a consistent state.) Another option would be to cluster your Boston and San Diego backup servers using your WAN connection. However, this quickly becomes complicated particularly if you want the flexibility to move your Exchange server frequently to multiple locations. It rapidly becomes clear that the flexibility of VMotion combined with global data movement creates new challenges.

Virtualized infrastructures provide tremendous business value by enabling many virtual machines to run on one physical machine. Now EMC comes along and suggests that VPLEX could enhance the storage efficiency and flexibility by enabling dynamic data movement. The big problem is data protection. The process of protecting VMware has always been a challenge although VMware has made great strides with the launch of vSphere. VPLEX’s geographic movement creates new challenges. End users need a backup solution that can handle the dynamic movement of VMs over long distance while ensuring that applications are always maintained in a consistent state. The backup solution also needs robust scheduling and tracking mechanism to enable the creation, management, recovery and deletion of consistent VM backups independent of physical location.

It is unclear who will be the eventual winner in global VMware protection.  Incumbent ISVs have a strong presence, but there is room for new players with VMware-centric technology.  Clearly, EMC owns one stack with Legato, VPLEX and VMware and will try to dominate.  However, there are likely to be a range of solutions and choice is good for the end user.  The good news is that there is time since true long distance storage virtualization products will not ship until 2011.

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