Software for running multiple operating systems on "virtual machines" will soon let those machines share the same memory.
VMware, whose software lets a single workstation run multiple operating systems, has begun testing a version of software that uses memory more efficiently.
The number of independent operating systems VMware Workstation currently can run is limited by how much memory a computer has, because each copy—called a virtual machine—needs as much memory as a regular standalone computer. VMware Workstation 5, however, will employ technology that lets the same memory be shared by similar virtual machines.
For example, a machine with 10 instances of Windows, each using 512MB, needs about 5GB of memory today, but typical tasks will let that be cut in half to about 2.5GB, said Michael Mullany, vice president of marketing at VMware. Under best-case circumstances, new virtual machines occupy only 8MB to 12MB, he added.
The new edition is due in the first half of 2005. Like predecessors, it runs only on computers using x86 chips such as Intel's Pentium and Advanced Micro Devices' Opteron.
The memory-sharing feature was first introduced in the company's high-end product, ESX Server, about two years ago, said Srinivas Krishnamurti, the company's workstation software product manager.
The EMC subsidiary's basic virtualization technology has been available for years, but the company continues to refine it and add features as new competition arrives in the market. VMware faces competition chiefly from Microsoft, but also from SWsoft, Sun Microsystems and start-up VirtuOS Computing. But VMware is well entrenched in the industry through established partnerships with IBM, Dell, Hewlett-Packard and most recently Oracle.
Boosting memory efficiency is helpful for developers who might want to employ another new feature called Teams, Krishnamurti said. Teams makes it easier to use a single workstation for simulating a multiserver infrastructure—for example, one with a Web browser, a Web server, an application server and a back-end database server.
Teams lets a developer start and stop an entire collection of linked virtual machines, Krishnamurti said. They also can control factors such as boot order so foundational machines such as database servers start up before other modules. And networking links can be throttled to simulate low-speed dial-up connections.
Another feature coming with version 5 will be a better ability to save "snapshots" of the virtual machine, a useful technology for those who want to store a particular state before trying risky software. Currently, only one snapshot may be saved, but version 5 will allow any number, Krishnamurti said.
The new edition will include another tool called "V2V" that will make it possible to convert Microsoft virtual machines to VMware virtual machines.
VMware Workstation works with two categories of operating system: the hosts on which the software runs and the guests that can run as VMware virtual machines. Version 5 will add some new hosts, including SuSE Linux Professional 9.2, SuSE Linux Enterprise Server 9 and Mandrake Linux 10. It will come with experimental support for the beta version of Windows Server 2003 SP1 and Red Hat Enterprise Linux 4.0, both due in 2005.
The software also will support 64-bit versions of host operating systems from SuSE, with experimental support for Red Hat Enterprise Linux 4, Windows XP and Windows Server 2003.
The list of supported guest operating systems is the same as that for hosts, but also includes Sun's Java Desktop System, VMware said. Sun's version of Solaris for x86 chips isn't on the list, though.
"Solaris is one of those operating systems that has some presence in the market, but as of today, it's not large enough to justify adding support," Mullany said.