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Chapter 4.  Capabilities and Limits

This chapter documents the capabilities and limits of Red Hat Enterprise Linux 5 as of minor release Red Hat Enterprise Linux 5.5.
Red Hat maintains a technology capabilities and limits page for Red Hat Enterprise Linux at This page provides the theoretical limits supported by the software as well as certified limits for generally available hardware. The theoretical limits are updated with every major release. Certified limits reflect the current state of system testing by Red Hat and its partners for mainstream hardware.


All the certified limits documented in this section are current as of March 30th 2010.
Maximum Logical CPUs
Logical CPU is defined as the number of CPUs that are presented to the operating system by the hardware. Multi-core processors and hyperthreads increase the number of logical CPUs that are visible to the operating system.
x86 32
Itanium2 256
AMD64/Intel64 64
Power 128
System z 64 (z10 EC)
Maximum memory
x86 16GB
Itanium2 2TB
AMD64/Intel64 256GB
Power 512GB
System z 1.5TB (z10 EC)

Note: This documentation is provided {and copyrighted} by Red Hat®, Inc. and is released via the Open Publication License. The copyright holder has added the further requirement that Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. The CentOS project redistributes these original works (in their unmodified form) as a reference for CentOS-5 because CentOS-5 is built from publicly available, open source SRPMS. The documentation is unmodified to be compliant with upstream distribution policy. Neither CentOS-5 nor the CentOS Project are in any way affiliated with or sponsored by Red Hat®, Inc.