The Unix Guardian--BrandZ Containers, xVM Partitions to Host Legacy Solaris Applications

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Volume 4, Number 36 -- October 4, 2007

BrandZ Containers, xVM Partitions to Host Legacy Solaris Applications

Published: October 4, 2007

by Timothy Prickett Morgan

Unix operating system and server maker Sun Microsystems has put a brand name on its implementation of the open source Xen hypervisor from XenSource, soon to be part of Citrix Systems: xVM. The x is for X64 and maybe X86 and the VM, of course, is for virtual machine. Sun is also talking about how it can take its Solaris containers and adapt them to supporting applications that were coded for older versions of Solaris, not just Solaris 10 virtual private servers or a Linux runtime environment.

Over the years, Sun has added various kinds of partitioning to its systems. The Sparc-based "Starfire" servers from the dot-com boom had hardware partitions, called domains, and then Sun made these reconfigurable (with a reboot) and called them dynamic domains. Domains were limited to partitioning at the system board level, however, so Sun decided to offer an alternative partitioning method, which it called Solaris contains, that has a single kernel and operating system providing virtual private servers atop the Solaris kernel. With the Sparc T1-based "Niagara" servers, Sun has a slightly different hypervisor-based partitioning method, called LDoms, short for Logical Domains, that allows a 32-thread T1 processor to support from 1 to 32 whole instances of Solaris 10 on a single processor--one instance per thread being the maximum.

These containers, which became available with Solaris 10, are not the same thing as the xVM partitions, but they are similar conceptually with the Xen-based xVM hypervisor. LDoms are only available on Sparc T1 and future T2 processors, and are not available on regular Sparc processors, however, and xVM (and Xen) are only available on X86 and X64 processors. Sun does, of course, support VMware's ESX Server 3 hypervisor on its X64 servers, and Solaris 10 can run as a guest environment atop this hypervisor, just as Windows, Linux, and NetWare can.

It seems highly likely that the future 16-core "Rock" UltraSparc RK processor, which is expected to ship in systems in the second half of 2008, will include LDom support. Sun could conceivably backcast LDom support to older Sparc gear, but the feasibility of this depends in large measure on how the LDom hypervisor works and what electronics are in UltraSparc-III, UltraSparc-IV, and UltraSparc-IV+ chips to support a hypervisor. With Sun wanting to sell new gear, putting LDom support on older Sparc gear would not exactly drive a lot of new business. So even if it is technically able to do so, it seems unlikely Sun will do this. Sun wants to sell lots of Sparc T2 and UltraSparc RK iron to customers who want virtualized Sparc-based Solaris environments, after all. (The Rock chips will appear in a new server design code-named "Supernova.")

For X64 customers, Sun is going to focus on xVM, its implementation of Xen, which will appear in the Project Indiana update of Solaris sometime around March 2008, give or take. The Sun-sponsored OpenSolaris development organization for the Solaris platform, which was taken open source two years ago to better compete against Linux, has for the past year been weaving the Xen hypervisor. Project Indiana is concerned with making it possible to take OpenSolaris source code and various open source applications ported to Solaris and creating something that is akin to the Fedora or openSUSE development releases of Red Hat's and Novell's respective Linuxes.

xVM will allow Windows and Linux--and indeed any operating system that runs atop a Xen hypervisor on an X64 platform, should Sun decide to support it--to run inside of Solaris. That makes Solaris into a management platform for these other operating systems, so DTrace monitoring tools, for instance, will be able to poke around inside running Windows instances and their applications from the Solaris layer and provide system telemetry--even though Windows does not support DTrace. (This is not new. IBM's logical partitioning for Power-based servers has offered similar functionality for i5/OS, AIX, and Linux for years.)

Sun demonstrated xVM running Windows at Intel Developer Forum a few weeks ago, but it is not clear when it will make it to the production-level release of Solaris, be it release 10 or 11. Project Indiana is not expected to be a commercially supported, enterprise-hardened Solaris release, after all. xVM has to be moved into the future "Nevada" production release of Solaris, presumably to be called Solaris 11, or added as a pretty substantial update to Solaris 10 to have full commercial support. (Yes, I know Solaris Express Developer Edition now can be included in existing Solaris 10 support contracts.)

Sun could, of course, position xVM to support all prior X86-based versions of Solaris, reaching all the way back to Solaris 2.1; that operating system (which was announced in March 1993) also ran on X86 chips as well as on Sparcs (which got support for Solaris 2.1 in December 1992). This seems like a lot more work than it is worth, especially considering that legacy Solaris applications are generally on Sparc, not X86, iron.

LDoms, xVM partitions, Project Janus Linux runtime containers for Red Hat Enterprise Linux 3 and Centos3, and Solaris containers for Sparc and X64 platforms do not solve all of Sun's platform issues. Sun is finally getting around to taking the Solaris container technology (which has the same framework whether it is on Sparc or X64 iron, and which was for many years known as BrandZ) and adapting it so containers running on Solaris 10 can support instances of older Solaris environments.

Exactly how this will be done is not clear, but Dan Roberts, director of Solaris, OpenSolaris, and database marketing at Sun has confirmed that Sun is working on such capability, and Marc Hamilton, vice president of Solaris marketing at Sun, gave a name to a special porting program for moving Solaris 8 workloads to BrandZ containers, which he called "eTude" in in a recent blog entry. eTude is a services engagement Sun plans to sell to move Solaris 8 workloads into BrandZ containers that are configured to look and feel like Solaris 8 instances, even though they are on Solaris 10 boxes.

Roberts said that Sun will support Solaris 8 workloads, including preserving the environment and settings of the Solaris 8 instance, first inside the BrandZ containers, since Solaris 8 support is what customers are asking for most. (If Sun had BrandZ containers running Solaris 8 five years ago, it would not have lost so much business to Linux platforms and alternative Unixes, but that is water under the bridge and far out to sea.) Sun could obviously support Solaris 9 containers on Solaris 10 machines, since Solaris 9 was available for X86 platforms even if Sun did not support it aggressively. Ditto for Solaris 7, which was also supported on X86 iron. Support for Solaris 2.5 and 2.6 containers would be very useful for severely legacy Solaris applications.

In any event, Solaris 10 platforms supporting BrandZ containers that look and feel like Solaris 8 instances are due later this year, according to Roberts. This support will probably come through an update patch, and hopefully will not slip into 2008.