With the release of Red Hat Enterprise Linux (RHEL) 6.3, Red Hat has tweaked the enterprise grade Linux distribution to add new capabilities in storage, virtualization, security, scalability, and performance.
"This is one of largest update release to date," said Tim Burke, Red Hat vice president of Linux engineering development. "It has a lot of performance scalability optimizations specifically targeted at virtualized cloud deployments in the data center."
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To improve overall performance, RHEL 6.3 features a new technology called NUMAD (Non-Uniform Memory Alignment Daemon). NUMAD is based on ideas behind NUMA (Non-Uniform Memory Architecture), a memory management technology developed for supercomputers with large-scale distributed memory. NUMAD will align data in working memory so it is most easily accessible by the processor working on the data.
"The way memory is wired on the chips, data is closer to access from some CPUs than from others," Burke explained. "It takes a lot of smarts from the OS to balance the workloads." Typically, an OS will move the jobs to least-used CPUs, with no regard to where the corresponding data is located. The distance between the CPU and an inconveniently located memory location slows system performance as a whole. NUMAD monitors the system at runtime and watches for memory usage patterns. "It will dynamically balance the workload to balance for both memory and CPU optimizations," Burke said.
The company has added a number of new features and enhancements to aid in virtualization. A new tool, called Virt-P2V, can package all the software running on a server into a virtual machine, so it can run on the KVM (Kernel-based Virtual Machine) hypervisor. It can translate either RHEL of Microsoft Windows environments into virtual packages.
This release also improves RHEL's scalability. Virtual machines running on RHEL 6.3 can now run 160 virtual CPUs (vCPUs), a boost from the limit of 64 in the previous version. Now a single virtual machine can take up to 160 CPUs on a given server. Virtualizing such large workloads can ease the process of moving them from server to server, Burke explained. The memory per KVM guest has also been upped to 2TB from 512GB.
The release also improves security. For example, the new version of the software complies with Payment Card Industry Data Security Standards (PCI-DSS) for deleting no-longer-need virtual machines from servers. It also has been prepared to work with the new, stronger AES-CTR (Advanced Encryption Standard Counter Mode) cipher, which will be used for RHEL's OpenSSH (OpenBSD Secure Shell). AES-CTR is particularly well-suited for high-speed networking environments. In addition, RHEL 6.3 supports two-factor authentication. Administrators can set up RHEL servers so they require not only a password but also a public key as well.
A lot of advances have been made in storage as well. The FUSE (File system in User Space) can be configured so that all reads and writes are done directly to the storage device, bypassing the server cache. This approach could make response times more consistent. Administrators can now do all their RAID management through the Logical Volume Manager (LVM), which now supports RAID levels 4, 5, and 6. This eliminates the step of working with RAID through the mdadm utility. LVM now includes thin provisioning.
"Thin provisioning allows you to over provision. Not all of your guests will consume all of their [allotted storage] space, so it is a waste just to have it sitting around in case the user would hit their maximum" allotment, Burke said. Previous RHEL thin provisioning capabilities required special disks; this version can use any disks.
Also on the storage front, RHEL can now act as a storage host for FCoE (Fibre Channel over Ethernet) storage networks.
As with any update, the software includes updated drivers for the latest hardware. It comes, for example, with a compiler for Intel's recently released Xeon E5 processor family. On the software front, RHEL 6.3 includes OpenJDK 7, the open source implementation of Java Standard Edition 7.
Red Hat has also made some changes with how it manages its support subscriptions. The Subscription Asset Manager (SAM) will start using X.509 certificates to identify supported machines. Also for the first time, subscriptions can be managed on the local machine.