[1] Supported limits reflect the current state of system testing by Red Hat and its partners for mainstream hardware. Systems exceeding these supported limits may be included in the Hardware Catalog after joint testing between Red Hat and its partners. If they exceed the supported limits posted here, entries in the Hardware Catalog will include a reference to the details of the system specific limits, and are fully supported. In addition to supported limits reflecting hardware capability, there may be additional limits under the Red Hat Enterprise Linux subscription terms. Supported limits are subject to change as on-going testing completes.
[2] Red Hat defines a logical CPU as any schedulable entity. So every core/thread in a multi-core/thread processor is a logical CPU
[3] The "SMP" kernel supports a maximum of 16GB of main memory. Systems with more than 16GB of main memory use the "Hugemem" kernel. In certain workload scenarios it may be advantageous to use the "Hugemem" kernel on systems with more than 12GB of main memory.
[4] The x86 "Hugemem" kernel is not provided in Red Hat Enterprise Linux 5 or 6.
[5] The architectural limits are based on the capabilities of the RHEL kernel and the physical hardware. RHEL 6 limit is based on 46-bit physical memory addressing. RHEL 5 limit is based on 40-bit physical memory addressing. All system memory should be balanced across NUMA nodes in a NUMA capable system.
[6] Red Hat Enterprise Linux 6 does not include support for the Itanium 2 architecture.
[7] If there are any 32-bit machines in the cluster, the maximum gfs file system size is 16TB. If all machines in the cluster are 64-bit, the maximum size is 8EB.
[8] Officially support 125 CPUs across the entire machine.
[9] Requires Intel EPT and AMD RVI technology support
[10] UEFI and GPT support required for more that 2TB boot LUN support (https://access.redhat.com/kb/docs/DOC-16981)
[11] Security certification details are available at: http://www.redhat.com/solutions/government/certifications/
[12] Firefox, Thunderbird, and OpenOffice applications will be updated during the lifecycle