I’ve been talking to a number of users and providers of bare-metal cloud services, and am finding the common threads among the high-profile use cases both interesting individually and starting to connect some dots in terms of common use cases for these service providers who provide the ability to provision and use dedicated physical servers with very similar semantics to the common VM IaaS cloud – servers that can be instantiated at will in the cloud, provisioned with a variety of OS images, be connected to storage and run applications. The differentiation for the customers is in behavior of the resulting images:
Deterministic performance – Your workload is running on a dedicated resource, so there is no question of any “noisy neighbor” problem, or even of sharing resources with otherwise well-behaved neighbors.
Extreme low latency – Like it or not, VMs, even lightweight ones, impose some level of additional latency compared to bare-metal OS images. Where this latency is a factor, bare-metal clouds offer a differentiated alternative.
Raw performance – Under the right conditions, a single bare-metal server can process more work than a collection of VMs, even when their nominal aggregate performance is similar. Benchmarking is always tricky, but several of the bare metal cloud vendors can show some impressive comparative benchmarks to prospective customers.
A group of us just published an analysis of VMworld (Breaking Down VMworld), and I thought I’d take this opportunity to add some additional color to the analysis. The report is an excellent synthesis of our analysis, the work of a talented team of collaborators with my two cents thrown in as well, but I wanted to emphasize a few additional impressions, primarily around storage, converged infrastructure, and the overall tone of the show.
First, storage. If they ever need a new name for the show, they might consider “StorageWorld” – it seemed to me that just about every other booth on the show floor was about storage. Cloud storage, flash storage, hybrid storage, cheap storage, smart storage, object storage … you get the picture.[i] Reading about the hyper-growth of storage and the criticality of storage management to the overall operation of a virtualized environment does not drive the concept home in quite the same way as seeing 1000s of show attendees thronging the booths of the storage vendors, large and small, for days on end. Another leading indicator, IMHO, was the “edge of the show” booths, the cheaper booths on the edge of the floor, where smaller startups congregate, which was also well populated with new and small storage vendors – there is certainly no shortage of ambition and vision in the storage technology pipeline for the next few years.
This week, IBM announced its new line of x86 servers, and included among the usual incremental product improvements is a performance game-changer called eXFlash. eXFlash is the first commercially available implantation of the MCS architecture announced last year by Diablo Technologies. The MCS architecture, and IBM’s eXFlash offering in particular, allows flash memory to be embedded on the system as close to the CPU as main memory, with latencies substantially lower than any other available flash options, offering better performance at a lower solution cost than other embedded flash solutions. Key aspects of the announcement include:
■ Flash DIMMs offer scalable high performance. Write latency (a critical metric) for IBM eXFlash will be in the 5 to 10 microsecond range, whereas best-of-breed competing mezzanine card and PCIe flash can only offer 15 to 20 microseconds (and external flash storage is slower still). Additionally, since the DIMMs are directly attached to the memory controller, flash I/O does not compete with other I/O on the system I/O hub and PCIe subsystem, improving overall system performance for heavily-loaded systems. Additional benefits include linear performance scalability as the number of DIMMs increase and optional built-in hardware mirroring of DIMM pairs.
■ eXFlash DIMMs are compatible with current software. Part of the magic of MCS flash is that it appears to the OS as a standard block-mode device, so all existing block-mode software will work, including applications, caching and tiering or general storage management software. For IBM users, compatibility with IBM’s storage management and FlashCache Storage Accelerator solutions is guaranteed. Other vendors will face zero to low effort in qualifying their solutions.
I’ve been getting a number of inquiries recently regarding benchmarking potential savings from consolidating multiple physical servers onto a smaller number of servers using VMs, usually VMware. The variations in the complexity of the existing versus new infrastructures, operating environments, and applications under consideration make it impossible to come up with consistent rules of thumb, and in most cases, also make it very difficult to predict with any accuracy what the final outcome will be absent a very tedious modeling exercise.
However, the major variables that influence the puzzle remain relatively constant, giving us the ability to at least set out a framework to help analyze potential consolidation projects. This list usually includes: