The proliferation of virtual servers connected to data storage has given rise to a thorny storage management issue: How much control should server administrators have over storage? While there's no simple blanket answer to that question, it clearly points to a need for better communication between groups to handle end-to-end management of servers and storage devices.
Communication and management have become larger issues with virtualization because virtualization changes the way storage and servers interact, and also drives the adoption of networked storage in many shops. But many organizations have separate teams handling servers and storage. Those silo environments may result in a loss of visibility into application requirements and growing utilization rates that determine the amount of storage capacity a data center needs. That often requires storage and server teams to share data, as well as management decisions.
Administrators admit they grapple with this issue, which requires better management tools as well as a clear delineation of roles.
Tom Golson, chief systems engineer, Infrastructure, Systems and Services Group at Texas A&M University in College Station, said there's often a cultural divide between the groups. Storage administrators are more about wires and devices, while server administrators are operating system and software application specialists. But he said storage administrators need to provide more information to server virtualization administrators who don't necessarily need to see the storage but need to know enough to assign storage to the virtual machines (VMs).
"I don't think the issue is about control," Golson said. "It's about how the tools enable better separation of responsibilities. I believe you have that clear separation of duties when your storage products work well with your virtualization products. If not, then the storage and virtualization people need to know more details about the other side's operations because there are a lot of low-level decisions to be made."
Golson said his group started virtualizing servers approximately eight months ago and currently has about 40% to 50% of his infrastructure virtualized. He said his storage array vendor Xiotech has done a good enough job of integrating its systems management with server virtualization technology that he can approach it from a holistic standpoint.
"You can't just look at virtualization from a server standpoint or just from a storage standpoint," he said. "It's a very holistic discussion. The storage people need enough visibility into the server virtualization. There has to be more communication between the two tiers."
Sean Graver, storage architect at Concur Technologies Inc., said the server virtualization administrators need greater control when server virtualization drives changes in the storage environment. "It has to be from the server side," he said. "That's where the choices are being made and new loads are being added. That's where you have the ability to make choices."
However, there are likely some storage management functions you don't want the server team controlling. Dan Roesler, senior systems administrator at Houston-based Boardwalk Pipeline Partners LP, maintains both sides should have visibility into the virtualization and storage layers but any end-to-end management tools require restrictions.
"You don't want the virtual [server] administrators to have access to the [storage] knobs and buttons," he said. "For example, you don't want them allocating LUNs, etc. You want to cut it off where it's 'read only.' They should be able to see and understand each other's worlds but there should be restrictions to access."
Texas A&M's Golson agrees with that assessment. "Frankly, it horrifies me to have a storage manager see which VM is doing what," he said. "And I wouldn't want a virtualization guy playing around with a disk."
Survey shows virtualization usually requires storage management changes
A recently released Enterprise Strategy Group (ESG) research report indicates most large organizations are dealing with this issue. In a survey of 463 senior IT professionals in midrange and enterprise shops who had virtualized servers, 39% said server virtualization had significant impact on their storage teams and another 55% said it had some impact. Only 5% said server virtualization had little or no impact on storage. These numbers weren't that different than the impact on the server teams – 44% said it had significant impact, 53% said it had some impact, and 4% reported little or no impact.
Bob Laliberte, an ESG senior analyst, said there's a greater need for tighter integration among server, network and storage administrators. "There are people embracing the change," Laliberte said, "and they understand things need to be more tightly integrated."
He suggested workflows and processes that previously were separated should be automated. Laliberte said the storage team should remain in charge of storage, but it can provide policies to the server virtualization administrators that establish service-level agreements (SLAs) or storage availability.
Tools to deliver better visibility between storage and virtual servers are on their way. This year, VMware and storage partners are expected to release new APIs called VMware Aware Storage APIs (VASA) that would improve visibility into the physical storage infrastructure through vCenter and CapacityIQ. The VASA code will allow VMware administrators to view information about the physical storage array as well as the virtual data store.
Laliberte pointed to Hitachi Data System's full support of VMware vStorage APIs for Array Integration (VAAI) and NetApp's acquisition of storage resource management software vendor Akorri Networks Inc. as recent examples of storage vendors moving to add functionality to support server virtualization. Vendors that support server virtualization also recognize the potential management conflict.
Bryan Semple, chief marketing officer at virtual server capacity management vendor VKernel Corp., said havoc is created when there's spindle, fabric and I/O contention, and the two teams end up pointing fingers at each other.
"This is definitely a big problem," he said. "The question comes up [as to] how much data is enough and how much should you share between the server and storage teams. Our view is the virtualization administrator needs enough information so if there's a problem they can solve it when moving the VM to another host. When they call the storage team, they have to have enough information to give to the storage guys so they can fix it."