Red Hat NETSCAPE MANAGEMENT SYSTEM 4.5 Uživatelský manuál stáhnout pdf (Strana 252)

Resource Management

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512MB of memory. The native memory requirement with eight physical servers is 8 *

512MB = 4GB.

To consolidate these servers as virtual machines, 24MB is needed for the server

virtualization layer and 192MB is recommended for the console operating system.

Each virtual machine also requires an additional 32MB of overhead memory. An

additional 6 percent should be added to account for the minimum free memory level.

Assuming no overcommitment and no benefits from memory sharing, the memory

required for virtualizing the workload is 24MB + 192MB + (1.06 * 8 * (512MB + 32MB))

= 4829MB. The total overhead for virtualization in this case is 733MB.

If memory sharing achieves a 10 percent savings (410MB), the total memory overhead

drops to only 323MB. If memory sharing achieves a 25 percent savings (1GB), the

virtualized workload actually consumes 291MB less memory than it would on eight

physical servers.

It may also make sense to overcommit memory. For example, suppose that on

average, two of the eight Web server virtual machines are typically idle and that each

Web server virtual machine requires only 256MB to provide minimally acceptable

service. In this case, the hardware memory size can be reduced safely by an additional

2 * 256MB = 512MB. In the worst case where all virtual machines happen to be active

at the same time, the system may need to swap some virtual machine memory to

disk.

More Information

For additional background information on ESX Server memory usage, see Memory

Resource Management on page 239.

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Red Hat NETSCAPE MANAGEMENT SYSTEM 4.5 Uživatelský manuál Strana 252