New SAN, new transport, new opportunity

Next week, we’ll be taking delivery of a new SAN that replace our trusty AX4, which has reached both end of life and end of warranty. We’ve really pushed the heck out of our AX4; it houses 1,500 Exchange mailboxes, a dozen or so enterprise SQL server databases, and terabytes of file-based data accessed via a virtual server. In addition, the AX4 currently supports our four vSphere hosts which support fifty or so virtual machines. Frankly, we’re doing more with the AX4 than I thought would be possible when we acquired the unit… and we’re doing it all on iSCSI, which has been the transport medium of choice for my SAN choices since 2004. Next week, though, we’ll be moving to Fibre Channel with our new SAN. Doing so will require some additional implementation effort but as we continue to expand our offerings to include VDI, I never wanted to see the transport become a limiting factor. I still believe that iSCSI is a tremendous choice and probably would have met our needs long-term, but we’re taking the plunge. From a cost perspective, we’re not looking at much more money, even for a pair of Fibre Channel switches, so I’m not too concerned about the switch.

What does this mean for us, though? What will we have to do?

  • For each ESX host (Dell M600 and M610 blades), we’ll need to remove an existing Ethernet adapter and replace it with a Fibre Channel adapter. We already have these on hand. Each of our servers has six network connections
    • Front end 1
    • Front end 2 – redundant
    • Vmotion
    • Management
    • iSCSI 1
    • iSCSI 2 – redundant
  • As a part of this effort, we’ll need to reconfigure one of our iSCSI links to temporarily use a different network adapter while we make the change. We’ll repurpose our redundant connection to the front end network for this purpose and, once we’re done, re-establish the redundancy.
  • Once we’ve replaced the Ethernet mezzanine card with a Fibre Channel one, we’ll make the necessary configuration changes in vCenter for each vSphere host.
  • At this point, each ESX host will be on both SANs. Over time, we’ll migrate each virtual machine to new volumes on the new SAN.
  • When done, we’ll shut off the AX4.

That’s it! Although it will be a relatively complex undertaking, I’m very confident in our ability to do this right and get it done. As we move through the process, I will report back and let you know if we run into any problems. I’ll also be reporting back with information about how we migrate between the two SANs.

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