Samba 4.0 features additional support for IPv6 and connects to a System Security Services Daemon in RHEL6 that allows centralized access to different identity/authentication services, such as linking LDAP with Kerberos, Active Directory, and so on.
Products like Synchronicity and Microsoft acquisition Zoomit have provided similar directory/authentication mapping services, but RHEL6 is the first to put this into the kit.
Installation has become more sophisticated. We installed RHEL6 onto VMware ESXi, which had a configuration wrapper available to deal with RHEL6 specifics before RHEL6 was released.
The installation GUI also has detailed specs to install storage devices. If you want your server to use iSCSI or Fibre Channel over Ethernet, you get device and method-specific help and the same is provided for detected storage-area network (SAN) devices or firmware-based RAID drives.
RHEL6 also takes advantage of multi-queue networking. While we were unable to test this, we find its inclusion encouraging, as it gives administrators the capability to assign core-specific I/O tasks at a low-level, meaning that traffic doesn't have to go up and down an application stack to get CPU boosts.
Support for kernel-based KVM hypervisor virtualization is native (as it is on Ubuntu Server) and supports up to 64 virtual CPUs on virtualization-enhanced AMD and Intel server platforms.
CPU drivers (actually extensions) are available to put into virtual machines running atop KVM to enhance the virtual machine's ability to support updated CPU instruction sets.
Like paravirtualization, which makes generic socket connections to network and storage devices, CPU extensions allow applications written with advanced libraries (and their instruction sets) to skip the step of interpretation when the hypervisor must deal with complex VM instance states. The result ought to be higher efficiency between hypervisor host and VM.
We examined how RHEL6 plays into cloud platforms and came to several conclusions. (See how we conducted our test.)
1. Where a server is the host to user environments, RHEL6's SELinux controls, coupled with advanced Control Group use, permits a user and session resource partitioning profile that places a number of walls and limitations around users/tasks. As a user/process host, it passes nicely.
2. Where RHEL6 becomes a host for the random/sporadic traffic associated with private cloud virtual machines, RHEL6 is poised towards virtual machine life-cycling.
But it has no inherent applications that spin up instances the way an enlightened civilian might like, and so private cloud management tools are needed.
3. Using RHEL6 in the public cloud ought to be simpler, as RHEL6 can play with its KVM use and ability to confine instances with SELinux and cgroups.
4. We found KVM simpler to install and support than XenServer 5.6 (the latest version), but it's ultimately not as full-featured as XenServer.
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