10 things you need to know about Red Hat Enterprise Linux 7
Red Hat Enterprise Linux 7 is more proof that operating systems aren’t dead, they’re becoming vessels for containerised applications.
Tom Henderson, NetworkWorld
RHEL 7 performed well in our testing, but it’s worth noting that this no longer just a simple OS – it’s an increasingly abstracted component in the larger Red Hat ecosystem. In testing, we found that the RHEL 7 OS stands alone well, plays well with others, and is easier to both deploy and configure.
1. 1. Increased support for Windows
Red Hat has increased support for hosting Windows products in this release. For Red Hat, Microsoft is less of a target and more of a grumbling ally in terms of systems support. Overall support for hosting virtualised Windows Server Editions is less obscure than when we tested RHEL 6. And with an updated SAMBA 4 (an SMB/CIFS/AD connector), RHEL 7 is an almost full member of a Microsoft network, where others, like Apple, are balkanised by lack of simple Windows compatibility in business turfs.
2. 2. Tuned for stable business deployment
Red Hat has the onus of an OS subscription model that prevents instances from being out-of-support or highly re-configured - no interesting but unstable kernels allowed. The hackability of this OS is poor, but hacking is what other Red Hat and Fedora derivatives are for. This one’s all about stable business deployments. The Red Hat core may be inviolate by policy, but for some systems personnel, better the devil you know, than the apt-get you don’t.
3. 3. Code base gets larger
Like Canonical’s Ubuntu 14.04, RHEL 7 is a huge pile of code, running 4.3GB in the DVD ISO we downloaded.
4. 4. Support for LinuX Containers (LXC) and Docker for virtualised workloads
Red Hat is supporting application instance isolation methods that revolve around Linux containers/LXC. The pre-production use of Docker instance provisioning methods we described in Network World's recent Ubuntu Server review allows developers to further the concept of workload isolation. Red Hat’s support of LXC is aimed at making it more attractive for users to deploy Type-2, OS-based virtualisation, rather than Type-1 bare metal hypervisors. LXC allows the container to be both lightweight, yet highly isolating.
5. 5. Support for Project Atomic
Making containerised workloads the basic unit that fits into generic containers allows them to be liberated from a RHEL 7 instance. If all works well, moving a workload from one OS instance to another is transparent to the workload. It then becomes the job of relationship stack components - especially OpenStack - to manage, deploy, secure, provision, and move workloads among hosts. Red Hat sponsors Project Atomic, which surrounds Docker. Once an app tests successfully as an isolatable container instance, it can become a package, much as software appliances are found and deployed.
6. 6. Support for xfs file system
RHEL 7 now uses the xfs file system instead of ext4 by default. Support for xfs means that RHEL can handle extremely large file systems, as much as 8 exbabytes – which is supported by no hardware we can imagine and therefore is theoretical. Red Hat’s support goes to only 500 petabytes apparently. We did not test either claim.
7. 7. Tighter links to Active Directory
Those desiring cross-platform compatibility with Windows Active Directory receive new Kerberos support that allows them to do this, subject to caveats regarding Kerberos time synching—and time-synching to the same host and time-zone adherence becomes a pre-requisite, we’ve found. Identity management is cross-platform between the two. We linked our Red Hat identity to our in-house Windows 2012 R2 Active Directory domain without a hitch. Much of this comes at the behest of RealmD, a system process that looks up resources via DNS.
8. 8. Easier to install and deploy
The RHEL 7 kernel update to 3.20 is similar to Canonical’s implementation, but in terms of distribution, we found RHEL7 slightly easier to deploy on bare metal, and about the same on VMware, Hyper-V, and Citrix XenServer.Installation has changed, and very largely for the better. OpenStack installations were more sophisticated to initially orchestrate, but also worked without drama. We upgraded from RHEL6.5 to RHEL7. Again, no problems.
9. Built for business
At installation time, we could choose from several types of base environments: minimal, infrastructure server, file and print server, basic web server, virtualisation host, and server with a GUI. Each selection has a set of components to be chosen.
It’s not easy to stir-fry your own combination of items. We suggest using CentOS or Fedora for combinations that might be difficult or even bizarre to support, because Red Hat will do this, but it’s not going to be their core strength.
10. 10. Zippy in performance
In terms of performance, Gnome feels speedy, but the GUI-less server instances we deployed screamed. Optimisation for varying roles is fairly well documented, and Red Hat can increase throughput through a new feature of network port teaming. InfiniBand is easily supported for those with drive arrays or SSD or hybrid conventional SSD/conventional cached arrays. Red Hat’s initial discovery process found all of our multi-core/multi-processor beasts correctly. In fact, single core hardware platforms aren’t even supported. Multi-core is your only choice. Same goes for 32-bit CPU families: not supported.