Red Hat Enterprise Linux (RHEL) is a popular choice for cloud service providers such as Amazon and Rackspace to run workloads in their datacenters. The beta of version 7, released Wednesday, is equipped with containers to support movement of Linux workloads from the datacenter to the Red Hat OpenShift platform-as-a-service (PaaS) environment.
The online version of OpenShift runs on top of Amazon Web Services' EC2 cloud, so developers using Red Hat Enterprise Linux have a sanctioned and soon-to-be-supported way to move workloads back and forth between the enterprise datacenter and OpenShift. The containers feature will be fully supported once RHEL 7 is generally available, sometime in 2014, said Mark Coggin, senior director of product marketing, in an interview.
RHEL 7 takes advantage of containers in the Linux kernel, but Red Hat has added its own namespace management, security, and resource management to RHEL's version of containers.
Containers are logically defined slices of system resources in which an application can run. One host can generate and run many containers, each holding its own copy of an application. Containers improve operation efficiency when several copies of an application use a shared resource, such as a database or data retrieval system, on a shared host. But for containers to work properly, each shared resource must have a clearly defined namespace in which its processes run. That allows applications in multiple containers to share a resource without intruding upon each other's operation or corrupting the data.
[Want to learn more about Red Hat's platform as a service? See Red Hat Takes On VMware For PaaS Crown.]
Containerization is a form of virtualization that makes more efficient use of the operating system. With the older form of virtualization under VMware ESX Server, Citrix XenServer, or Microsoft's Hyper V, each virtual machine has its own, full copy of the operating system. On a containerized host, one copy is used by multiple applications, each in its own container.
Containers also have enough intelligence to move to a new environment, such as the OpenShift cloud, and register its needs under a slightly different version of the operating system. In one sense, the container has brought a piece of its former operating system into the new environment, just enough to keep its essential management functions intact, senior product manager Ron Pacheco told InformationWeek.
"Red Hat users are starting to move toward an open hybrid approach to cloud computing," said Coggin, and RHEL 7 is geared to help them start on that journey. OpenShift is Red Hat's online platform for developers, but it can also serve as a test deployment environment for a new application, a place to stage a new application before it goes into production, or the production environment itself.
Coggin said Red Hat may add additional cloud environments in the future, but didn't name Red Hat's next target environment.
RHEL 7 also adds the ability to mesh its identity management with a Windows Server and Active Directory environment. Linux and Windows are the principal co-inhabitants of many enterprise datacenters, and Red Hat has implanted "cross-realm trust" with Active Directory in RHEL 7.
In the past, a systems administrator had to do a manual configuration to allow Enterprise Linux to directly hand off users to Active Directory. Red Hat has used RealmD open-source code, which can work between Linux's Kerberos identity management system and Active Directory to hand off policies and privilege levels with user profiles. Active Directory can then grant access to resources.
"We acknowledge the world is very heterogeneous. We need to coexist with Windows Server," said Coggin.
The default file system in RHEL 7 will become XFS (extended file system), replacing EXT 4 used in RHEL 6. EXT 4 was limited to managing 16 TBs of address space; XFS can manage 500 TBs. EXT 4 will still be included in RHEL 7, and its limit will be pushed up to 50 TBs, for customers who want to continue using it, said Pacheco. XFS was created by Silicon Graphics for its Irix operating system. SGI later made it open-source code, and it was then incorporated into the Linux kernel.
RHEL 7 also includes more application performance management features, and its Performance Co-Pilot can monitor and analyze system performance through samples or traces of its processing. It resembles Dtrace in Solaris, where specific parts of a system can be inspected and analyzed if they're suspected of slowing operations.
RHEL 7 also increases the degree of integration between an Enterprise Linux guest operating system running in a virtual machine and VMware's vSphere virtualization management system. RHEL 7 includes Open VM Tools, or tools designed by VMware and released as open-source code for virtual machine applications to run under Linux. It also has speeded up communications between the ESX hypervisor and the virtual machine.
Charles Babcock is an editor-at-large for InformationWeek, having joined the publication in 2003. He is the former editor-in-chief of Digital News, former software editor of Computerworld, and former technology editor of Interactive Week.
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