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A Primer on the New Hyperconverged Systems

May 22, 2018

So hyperconverged systems running AIX are here, and it's very cool. If you're looking for more technical detail, the IBM Knowledge Center provides some practical information that techies will find very interesting. This doc features concepts and recommendations on planning, deploying and installing AIX, network booting and configuring virtual machines. There's also a section on troubleshooting.
Here are some interesting tidbits:
  • AIX cannot determine the number of physical cores in the system and reports a large default value when running on IBM Hyperconverged Systems powered by Nutanix.
  • The system administrator must use the Nutanix PRISM GUI to obtain information about system capacity for capacity planning and software licensing purposes.
  • Nutanix does not support micro-partitioning of CPUs or shared processor pools with entitlement controls found on PowerVM based systems. When the AIX operating system is running in this environment, AIX represents all virtual processors as fully entitled and having capped shared CPUs.
  • The AIX operating system supports virtual I/O Ethernet and SCSI devices (virtio-net and virtio-scsi types) by using the KVM VirtIO virtualization standard that is used in IBM hyperconverged systems. The AIX operating system also supports the CD device (spapr type) used in this environment.
  • Hyperconverged systems use fully virtualized I/O; therefore, workloads that rely on physical I/O are not supported.
  • AIX on IBM Hyperconverged Systems powered by Nutanix supports installations through AIX cloud images and DVD ISO media. This environment also supports installations through traditional methods for network-based installations by using the NIM that is currently supported on PowerVM systems.
  • You can access the AIX console through the PRISM GUI by using the COM1 console connection after the VM has been started. You must use a VNC console connection to interact with the open firmware.
  • If you're using a static IP address for the client VM, the client and server must be on the same subnet when booting a VM across the network. You cannot specify a subnet mask in the boot command as shown in this example:
    • 0> boot <NIC-device>:<nim-server-ip>,<\path\to\client\bootfile>,<clientip>,<gateway-ip>
    • 0> boot net:,\tftpboot\,,
  • You must restart the AIX VM when you change the number of CPUs, amount of memory, and after adding or removing a network device or CD-ROM device.
  • AIX supports serial console connections on IBM Hyperconverged Systems. You must choose the COM1 connection while launching a console from PRISM to interact with the AIX operating system.
  • The VNC console connection must be used to interact with open firmware before the AIX operating system is loaded after starting or rebooting a VM.
  • As the VM loads the AIX operating system and software drivers, AIX IPL progress codes are displayed in the COM1 console.
  • AIX does not provide concurrent diagnostics support, including adapter firmware updates, for IBM Hyperconverged Systems powered by Nutanix. The Nutanix product provides support for device diagnostics and firmware updates.
Rest assured, I will continue to find ways to get hands-on with these clusters, and let you know what I learn along the way. I've been asked why this is such a big deal, and there's a simple answer: It's AIX running on what's essentially a new and different hypervisor. In short, there's another way to run our favorite OS.  
Here's another way to look at it: Different skills are needed to manage AIX and Power systems. You need to learn the HMC and keep up with the changes to the interface. You also have to learn the VIO server and how dual VIO failover works, etc. You have to learn SMS, ASMI and so many other things. Sure, we all understand this stuff, we like working with this stuff, but it is a barrier of entry for new admins.  
Having been hands-on with the Prism interface, I can tell you that it's far simpler to use than the HMC and VIO server interfaces. Again, that's nice for us, but when you think of the newcomers to AIX, it's huge. Along with that, if you're already using Nutanix in your datacenters, it's a snap to add in a POWER-based cluster and receive the performance advantages of both Linux on Power and AIX.
"Game-changer" is pretty cliched techspeak at this point, but it fits here. The capability to run AIX on Nutanix is a game-changer. I hope this gives you an idea of the different things you'll be able to do with AIX going forward.

Posted May 22, 2018| Permalink