Basic Information about Images in the VCL
To create an image, you start by using a base image or another existing image as your “base”, install whatever applications or make whatever changes you want, then save it as a new image. You can also make updates to images that you’ve created, and save that as a new version of that image. You identify which version of your image that you want to be the production version, i.e. the version that users will get when they request that image.
When you first create an image, you are the only one that has access to it. In order to make it available for others to use, you must add it to an image group. Image groups can control who has access to an image, as well as what servers the image can be run on. There are two image groups to which all users have access by default, “allUsers” and “allUsers vmware“. The difference between these is based on the type of image, bare-metal or virtual.
Bare-Metal vs. Virtual
There are two types of images on the VCL, “bare-metal” or “full blade” images which use an entire physical server, and “vmware” or virtual images which run on virtual servers that are managed by VMware. From the user perspective and an image administration perspective, there’s no difference in how you interact with them. However, they MUST be kept in separate groups. The bare-metal images should go in “allUsers” which is mapped to run on full servers, and the vmware images should go in “allUsers vmware” which is mapped to run on virtual machines.
It is typically preferable to create a vmware image. Load times for bare-metal images are typically around 20 minutes whereas vmware images load in around 6-8 minutes. This is due to the fact that there are several reboots during the imaging process, and a vmware reboot is software only. A bare-metal reboot is a hardware reboot of the server, which takes much longer.
To create a bare-metal image, use an image that has “Full Blade” in its name. To create a vmware image, use an image that has the word “vmware” in its name. Also follow the convention by adding the word “vmware” or “Full Blade” to your image name. This makes them easy to identify. You can verify an image type by clicking Manage Images, choosing Edit Image Profiles, then Submit. Under the OS column, vmware images will show VMware in the OS name.
More On Groups
As mentioned above, image groups are used to map images to run on specific groups of hardware. There are also user groups which can be used to give sets of users access to different image groups. Initially we are starting out very simply with just a few groups. As things develop, it may be desirable to create additional groups for various reasons. If you’d like to have a user group created for your image(s), please contact firstname.lastname@example.org.
For the general use hardware, there is an “allUsers” image group and “allUsers vmware” image group for virtual, which by default any VCL user has access to. This group is mapped to the general research computing hardware.