Tuesday, 29 April 2008

Is hypervisor-based virtualization doomed?

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Operating system isolation or hypervisor-based virtualization remains popular, but are we settling for less than what we should? Hiding its limitations in modest incremental effectiveness, hypervisor-based virtualization persists because it continues to hide an ugly secret: poor quality code.

Many who have worked with hypervisor-based virtualization may already knows this, but anyone who has attempted implementation of application instancing undoubtedly see where hypervisors fail. Replication of the operating system within a virtual instance is waste, waste driven by bad code. Faster cores, more cores per package, limited improvement in memory and device bus design, marginal increases in mechanical drive design and shared storage models have all contributed to mask how hypervisors inefficiently utilize processors.

If customer adoption rates are an indicator of success, past attempts at application instancing have not been successful to any consistent degree (there are no buzzwords for an application instance method.) To be clear, homogeneous applications have benefited, such as Microsoft SQL and ISS, Oracle and even Citrix. However, in the case of Citrix, application instancing has been environment-dependent to a degree.

Resource management within a common operating instance has not significantly changed since the introduction of mainframe logical partitions (LPARs).
Solaris zones is a container-based model, whereas AIX micro-partitions follow a truer application instancing model. Even Apple computer introduced simple memory partitioning in the Macintosh Operating System 7.x. DEC (yes, Digital Electronics Corp.) leveraged Microsoft Job Engine API, effectively a processor affinity layer, in a ground breaking concept product that Compaq buried. Does anyone remember that product?

The hypervisor foundation resulted from heterogeneous application partitioning failures. For Windows, application instancing has stalled at times or has otherwise been over shadowed by operating system instance isolation techniques. Windows SRM is a weak attempt to crack the hypervisor foundation, but it is so immature at this point it is useless.
Microsoft SoftGrid, now Microsoft Application Virtualization has a greater potential but is just not well accepted at this point. Should Microsoft provide it for free to drive acceptance?

The technology industry has attempted some rather interesting implementations to offset the impact of operating system instance isolation, for example, thin-disking and image-sharing which are based on eliminating disk partition under utilized space. Several attempts at addressing the DLL and .Net issues (e.g. Microsoft SoftGrid as well as Citrix) have been implemented to support heterogeneous application instancing but have masked the true issue that has always existed, the lack of quality code.

Why do I make this point? Because the hypervisor is essentially a band-aid on the boo-boo of bad coding. Quality code makes for stable environments. With a stable and predicable environment, applications can be run without fear of crashing, and it is this fear that gives hypervisor virtualization its strength. Poor software quality makes hypervisor-based virtualization more expensive than it should be and the publishers of operating systems love it. After all, the total number of operating system licenses purchased has not gone down with hypervisor virtualization. The industry has known for years that poor quality software has been an issue. One radical solution is to hold software publishers to a higher standard, but that idea has not gained enough grassroots support – yet. When it does, the hypervisor will be history.

Source: A guest blog written by Schorschi Decker, an IT professional specializing in virtualization and enterprise-level management.

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1 comment:

LanceW said...

I love the "...band-aid on the boo-boo of bad coding." line!

Not sure if I totally understand/agree where you are coming from. Yes some of virtualisation's benefits is isolating crashing code. But it is not the only benefit.

Portability and standardisation are pretty high up on the benefits list. A virtual machine can be moved from physical hardware to physical hardware, no questions asked so to speak. Particularly useful with Windows environments where hardware dependence is a pain.

That said, virtualisation (of the hypervisor/virtual machine variety) is being touted as a bit of a panacea for all our woes at the moment.

Hardware, OS and Application virtualisation all together in an automated environment is the nirvana I guess. (see Qlustres/OpenQRM and Cassatt for the automated bit)

Great post, thought provoking.

...boo-boo of bad coding...love it!