Quoting from the IBM official announcement:
IBM today announced expanded scalability enhancements to the industry’s most powerful virtualization technology z/VM. With this new release, z/VM version 5.3 can now host the industry’s largest number of virtual images on a single hypervisor — virtualization technology that makes one computer look like multiple computers — allowing customers to further optimize and consolidate their infrastructures.
Internal testing conducted by IBM reveals that the new virtualization product release can host more than 1,000 virtual images on a single copy of z/VM.
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In addition to enhancing memory utilization, the new software plans to deliver increased CPU capacity with support for up to 32 Processor Units — raising the limit from 24 to 32 processors — a 33 percent increase over the previous release of z/VM.
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z/VM V5.3 runs on IBM System z9 (z9 EC and z9 BC) and IBM eServer zSeries (z800, z900, z890, z990) servers.
IBM z/VM version 5.3 will be available for purchase on June 29, 2007 through IBM and IBM Business Partners.