VMLINK Automounter for Linux on z/VM

VMLINK extends the namespace of a virtual machine to include devices of (specifically disks owned by) other virtual machines.

Consider automounter point /vmlink, similar to /misc and /net. Under /vmlink, one can have target directories ("keys" in automounter speak) named vmid.addr where "vmid" is the owning virtual machine and "addr" is the address of a disk on that virtual machine.

The VMLINK automounter script uses the key, here yourvm.yourdisk, to "link" (at the z/VM layer) your disk, bring it online, and then mount it at the named location under the automounter point.

VMLINK automates referencing disks of other virtual machines on demand of the "client" guest. Host administrative action is required for authorizing such references. Host administration is not required for activating such references once authorized.

In other words, you must be granted the right to use another disk, but once authorized you do not have to engage the administrator to use a disk for which you are authorized. (The VM admin does not have to perform the "attach", which we call "link.)

Rushal Verma developed the VMLINK automounter script as an intern project under the Linux Foundation.

On CMS, vmlink is a command. On Linux, /vmlink is an automounter point.