Red Hat Enterprise Linux version 6.5 brings a number of KVM improvements that large IT shops have waited for, along with networking improvements and more.
Red Hat 6.5 updates are based on requests from large enterprises. The company cherry-picked from the changes happening upstream in the core kernel pieces, as well as hardware enablement to bolster RHEL stability, said Siddharth Nagar, product manager at Red Hat Inc.
RHEL 6.5 includes Kernel-based Virtual Machine (KVM) virtualization updates, with a server OS that is more elastic at processing workloads. Server admins can enable or disable virtual CPUs (vCPUs) in active guests without downtime. The Red Hat KVM hypervisor underwent improvements to support more memory on guests -- up to 4 TB -- and direct access to distributed storage via GlusterFS volumes.
The OS now supports submicrosecond clock accuracy on the local area network for virtual performance as close as possible to physical performance. Other networking improvements in 6.5 increase visibility into traffic.
"[Dynamic vCPU adjustment] seems like a small enhancement, but it is an extremely important one when you are trying to process billions of lines of data," said Brian Wagner, a Linux consultant from Wagner & Associates Groupware Services Inc. in Stow, Ohio, who helped several clients migrate to RHEL 6.5. He added that network stack updates in RHEL 6.5 will also help the interserver communications that underpin large virtualized environments.
The virtualization enhancements in RHEL 6.5 make "anything based on KVM on Red Hat better," Wagner said, with "more variable control over the KVM environment and faster network speeds."
This is true for enterprise users and cloud providers that need to dynamically adjust resources, Nagar said. Pushing scalability enables new applications to run on KVM, including many big data analytics jobs.
In large environments, the administrator could disable virtual processors for some applications on the virtualized servers and devote them to a processor-intensive application, such as a business intelligence platform, Wagner explained.
Consider a financial services company that executes trades in the workday then batch-processes them overnight. With RHEL KVM, they are "dedicating as many virtual CPUs to the guest that is servicing [trade] requests" during business hours, Nagar said, then switching the virtual processors to a different set of apps in the back office at 7:00 p.m.
Cloud providers that need to deliver capacity on the fly based on customer requirements can easily add more memory or CPUs as needed without rebooting.
The open source server OS wars
Will the 6.5 update keep RHEL the dominant enterprise-class, open source OS in the data center? Technical features aren't the main selling point, according to Sander van Vugt, an expert in Linux high availability, virtualization and performance.
"Open source code can move between each distribution and the many noncommercial distributions just weeks after a new release," said van Vugt, who contributes to SearchDataCenter.
Enterprise-class options are competing on third-party tool integration. "[SUSE Linux Enterprise Server] is a terrific distribution, but RHEL has a much better focus on distributed tools for managing servers ... [and is] also a first-tier supported product with most third-party vendors," Wagner said.
Many data centers have more than one Linux OS running on servers. RHEL, SUSE Linux Enterprise Server (SLES) and Ubuntu are the primary Linux distributions for enterprises, van Vugt noted.
Oracle Linux, while a small percentage of the enterprise server OS installed market, should also be considered because of its association with Oracle's applications. Because enterprise server deployments are complex, sophisticated support and troubleshooting from the OS vendor also matter when selecting a Linux distribution, van Vugt said.
Wagner sees Ubuntu taking over for SLES in some scenarios as the recommended second distribution alongside RHEL. Ubuntu's Debian package manager dpkg is "much more robust" for dependency-checking than Red Hat's comparable tool, he added.
SearchDataCenter executive editor Ed Scannell contributed to this report.
See the changes that RHEL 6.7 brings