All right, so the next topic I'd like to cover is the VIO server virtual optical media, and in particular, the virtual media repository. Now this is a good departure from what we were talking about earlier in this module, but actually it's related, okay? Because these are important concepts in working with Linux LPARs on power systems. Because what this provides the administrator is a simple mechanism to present optical media to the Linux operating system without having to have an optical device assigned to the LPAR or even installed on the physical machine. The use of virtual optical devices in a Linux LPAR is simpler than setting up and using a network based software repository. Its use is limited to software that has been packaged as an ISO image or a UDF file, and it is fixed, obviously, to the content of the ISO. What makes it simpler is that the image is stored on a VIO server as a file and is accessed by the LPAR using virtual adapters that are managed by a combination of the power hypervisor and the operating system's device drivers. So once the setup is done for the LPARs, the loading and unloading of the ISO images for use by the LPARs is quite simple. And the virtual optical devices being bootable makes it possible for you to actually do operating system installs from the virtual media. And you may find this at times to be very useful when you're, say, just starting to build an environment and the networking isn't ready or stable yet. And so there isn't anywhere to go to get network based installation images. The virtual optical media can be set up as read only, allowing for more than one LPAR to access the same virtual optical media resource. Again, think install, multiple LPARs installing at the same time from one file. This can be especially useful as well for enterprise software packages that are delivered as ISO files. You copy the media once into the media repository in the VIOS. And then you use it over and over again for all the LPARs where that software must be installed or updated. Further, the virtual optical media can be set up as read/write, supporting backups to virtual optical files rather than physical media. It's important to note that the configuration of virtual optical media is done using the HMC, which I covered in previous videos. You can also use a command set in the VIO server CLI to configure and manage the virtual optical configuration itself. But there are some parts that have to be done in the HMC, and then all can be done in the HMC. And, in fact, in later videos, I will explore those VIO server CLI commands because they can be helpful as an adjunct to your Linux system administration. Okay, I think walking through a sequence of graphics is the best way to show you the architecture and explain how it works. Done that before, seems to work well. All right, so let's start with slightly different than what I talked about. This is not the virtual media repository. This is a physical optical device that's on the machine and it's being virtualized to an LPAR. Okay, now this is different than the optical repository that I just talked about, like I said, but it's a way to virtualize optical, the actual optical drive itself, DVD, say. In fact, the DVD drive in the example is assigned to the VIO server. This means the VIO server controls VIO to the physical device, okay? On the HMC at the physical system level, you configure a virtual optical device picking the physical DVD drive and an associated LPAR. Okay, now the HMC is used to create virtual SCSI adapters between the VIO server and the LPAR, so that has to have been done. And then the virtual optical device in the VIOS and its relationship to that virtual optical device in the physical device, that's managed by the HMC as well, right? So there's a tie together there between the virtual and the physical. Now the LPAR's configuration is generally, it's required to be refreshed once that first configuration is done to kick off the discovery process. And the virtual SCSI adapter, if it needs to be discovered, and the virtual optical device is discovered, and then they become usable in Linux. Now the virtual optical device is defined a /dev/SRX name, just like a physical optical device would be. And what you load in the physical optical drive is the optical media that the LPAR will have access to. So this is a physical platter that's going to go into a physical drive. If you want volume to the media, you gotta walk over and eject volume one and put volume two in the tray. And, of course, to use the physical drive on another LPAR, you go back to the HMC and unassign from the LPAR and reassign the physical optical device to another LPAR. The physical optical device is assigned to only one LPAR at a time. All right, so you probably picked up on my sarcasm maybe referring to the limitations of the physical optical device configuration. And that's primarily in the media management in the single assignment of the optical device. Now, if you want a flexible media management and simple management of multiple different volumes by more than one LPAR, you need something that's not tied directly to the physical media device or the physical media itself. And so enter the file-based virtual media repository in the VIO server. So look what I added. First, the physical storage connected to the VIOS. Now as it shows, this is any supported storage assigned to the VIOS. And this is where we will build a virtual media repository, as is shown in the white and yellow boxes inside the VIOS. Now the white outer box is a volume group in AIX, and the yellow box within it is a file system. The volume group name is user specified. The system generated file system name is noted in the box. And again, the creation of the virtual media repository is done in the HMC, although the management of the virtual media repository can also be done using the restricted administrator ID in the VIOS CLI using a set of commands developed specifically for those tasks. All right, so the next step is the creation of the media in the repository. Now it shouldn't be a surprise that the media is going to be files, ISO files, that are stored in the file system that was just created in the previous step. And the file can be extracted from physical media in a drive that's assigned to the VIOS back to that platter again or from an ISO file that was accessed by other means, right, usually over a network. The extraction of the virtual media results in files being created in that file system, that system generated named file system that I referenced earlier. I'd recommend using the HMC to do this step, although this can be done using the restricted administrator ID in the VIOS CLI again. Note that the restricted administrator ID, when using that, the files are not to be and really cannot be directly manipulated. And I guess you should not be manipulating these files. This is something that the tools in the VIOS should be managing. And like in the previous step, there are VIOS CLI commands to manage the extraction and lifecycle of the media files. Now, the additional content the graphic shows the creation of the virtual optical drive device in the VIOS, right? Now, this device, like the one we created for the physical drive in the VIOS, will be presented to and recognized by the LPAR as an optical drive. Now this step has to be done on the HMC. You're now positioned to load or unload optical media files into the virtual optical drive on the VIOS to be seen and used by the LPAR. And note that you would create multiple of these virtual optical devices, one for each LPAR that you want to have access to this media repository. Media file management can be done on the HMC, which I recommend, or via the VIOS CLI. And more than one LPAR's virtual optical drive can be loaded at the same time with the same or different optical media files. All right, so finally, I'm not sure if you picked up on the subtle change in the graphic, but look closely at the LPAR. You now see a green DVD available. That is the ISO file being translated by the hypervisor and drivers in the LPAR into a usable optical media. And there you have it, virtualized optical media without any physical optical media in the path. [MUSIC]
