Several factors are considered in the formula for calculating
the queue depth limit.
The formula for queue depth calculation considers the following
factors:
- The maximum number of queued commands is per node and there are
two nodes in an input/output (I/O) group. The system must continue
to function when one of the nodes in an I/O group is not available.
Thus, an I/O group is considered to have the same number of queued
commands as a node. If a node fails, the number of paths to each disk
is cut in half.
- If a virtual disk (VDisk) is mapped so that it can be seen by
more than one server, then each of the servers can send commands to
it.
- If a device driver times out of a command, it immediately reissues
the command. The SAN Volume Controller will have both commands in its command queue.