Will VIOS Pushback Drive Direct-Attached Disk Comeback?
September 29, 2014 Alex Woodie
Simplicity used to be one of the hallmarks of the AS/400. You plug in the wires, fire up the applications, and the thing just runs forever. But in today’s world, virtualization reigns supreme. Along with that virtualization comes a level of complexity that can turn once-simple tasks into difficult projects. Now, there are indications that a growing wariness of virtualization technologies–not just VIOS but “i on i” virtualization, too–is driving us back to a simpler world of direct-attached disks.
You can’t blame IBM for building advanced virtualization technology. Driven by requirements from the world’s biggest companies, IBM has created System z mainframes and Power Systems that virtualize every resource, from the CPU and memory to disk and network I/O. In the IBM i world, layer upon layer of virtualization exist, from the Virtual I/O Server (VIOS) and PowerVM hypervisor to iASPS and TIMI (technology independent machine interface) itself. There really is no avoiding it.
When IBM introduced logical partitioning (LPAR) to the IBM i platform in the late 1990s, there was a learning curve associated with it. Since the launch of IBM i version 6.1 in 2008, the community has come to grips with VIOS, which virtualizes the disk and network adapters in a Power Systems environment, thereby eliminating the requirement that IBM i or AIX and their LPARs have actual drivers of their own for the physical adapters dedicated to them.
VIOS brings benefits and drawbacks. Since it lowers the number of network adapters required to connect to a storage area network (SAN), it drives down costs and boosts efficiency of the physical I/O adapters that are left. As midrange IBM i shops adopt SANs–particularly the Storwize series, which are proving popular–they naturally gravitate toward VIOS to drive efficiency.
But the drawbacks of VIOS have proved a sticking point. Since it’s an AIX application, it requires IBM i shop to set up, manage, and monitor an AIX partition. These skills are largely foreign to IBM i shops. Bigger shops can afford to hire or train somebody in AIX, but that’s a tougher thing to ask smaller IBM i shops to do. Tool vendors in the space, such as HelpSystems and Halcyon Software, have responded by building VIOS monitoring capabilities into their products, which helps those who have already moved beyond the core commands available in the OS.
These VIOS issues have played out since IBM i shops started adopting Power7 servers. As they move up to Power8 boxes, they’ve become more pronounced because IBM has shipped systems that offer a very limited number of slots for network adapter cards, particularly on smaller systems. There are some indications IBM may offer an expansion enclosure for Power8 servers, but it’s apparently not on the docket for the next round of announcements.
One company that’s helping users get the most bang for their Power buck, virtualized or not, is Midrange Performance Group. MPG has been supporting VIOS in its PowerNav performance monitoring solution for AIX and Linux for some time. Earlier this month, MPG announced that it’s giving its Performance Navigator customers a deep discount on the PowerNav offering so they can monitor VIOS. It’s not easy to get a clear view of IBM i performance problems when I/O paths are virtualized. That’s what MPG’s performance monitoring tools do–effectively allow users to cut through the haze of virtualization, so to speak, and get as close as they can to the bare metal.
MPG has seen a surge in interest in VIOS performance monitoring among its IBM i clients. “We are seeing an increase in IBM i users with external disk through VIOS,” Randy Watson, president and co-founder of the Boulder, Colorado, company, tells IT Jungle. “There’s not enough slots in the new Power8 servers to drive all LPARs with their own disk, as we have traditionally done.”
The lack of slots forces customers into one of two options: either use VIOS or host IBM i client LPARs in a host IBM i LPAR, or what’s known as “i on i” or “iVirtualization.” There are some indications that IBM i shops are increasingly looking to i on i virtualization as a way to avoid VIOS. The approach allows users to create a virtual bridge that allows the host partition to share its physical I/O adapter with client partitions. The drawback of this approach is that it creates a single point of failure. At least with VIOS, IBM supports the capability to create dual VIOS servers for redundancy.
Two years ago, Watson would have said the IT industry was firmly marching toward greater virtualization and adoption of external disk arrays. “But now I’m seeing rumblings in industry, in the storage industry in general, that people are moving back to direct-attached disk because the virtualization is such a headache that people have finally thrown their hands up and given up.”
This is not an IBM i-specific issue, but an industry-wide issue, he says. “From my little narrow point of view, it’s extremely difficult to even track how many LUNs you have, how big they are, and how full they are,” Watson says. With direct-attached storage, “at least I know where my data is.”
We’re never going to see the virtualization genie put back into the bottle. There are too many advantages to this approach, particularly among the bigger companies that drive technology requirements. But among shops of all sizes, there are concerns that the added complexity that virtualization brings may outweigh the benefits, particularly if it hurts system reliability, availability, and security.
Data is money in today’s world, and organizations need to ensure that the ways they’re collecting, storing, processing, and securing the data meet certain standards. Today’s massive data flows are creating all sorts of challenges for IT outfits, and forcing technologists to come up with new and innovative ways of handling data. Data and storage virtualization technologies that ease the handling of data will definitely have their place in the sun, but only if they don’t hurt an organizations’ ability to process, store, and protect the data in the process. For smaller organizations without the headroom to deal with virtualization, perhaps going back to direct-attached storage makes the most sense.