Virtual Disk Timeout

By default, if the service domain providing access to a virtual disk backend is down, all I/O from the guest domain to the corresponding virtual disk is blocked. The I/O automatically is resumed when the service domain is operational and is servicing I/O requests to the virtual disk backend.

However, there are some cases when file systems or applications might not want the I/O operation to block, but for it to fail and report an error if the service domain is down for too long. It is now possible to set a connection timeout period for each virtual disk, which can then be used to establish a connection between the virtual disk client on a guest domain and the virtual disk server on the service domain. When that timeout period is reached, any pending I/O and any new I/O will fail as long as the service domain is down and the connection between the virtual disk client and server is not reestablished.

This timeout can be set by doing one of the following:

• Using the ldm add-vdisk command.

  ldm add-vdisk timeout=seconds disk-name volume-name@service-name ldom

• Using the ldm set-vdisk command.

  ldm set-vdisk timeout=seconds disk-name ldom

Specify the timeout in seconds. If the timeout is set to 0, the timeout is disabled and I/O is blocked while the service domain is down (this is the default setting and behavior).

Alternatively, the timeout can be set by adding the following line to the /etc/system file on the guest domain.

set vdc:vdc_timeout=seconds

If this tunable is set, it overwrites any timeout setting done using the ldm CLI. Also, the tunable sets the timeout for all virtual disks in the guest domain.