An I/O error occurred when reading file data from an agent and saving it to disk. Examples:
An error of some kind has occurred when trying to read and record file data from an agent. The error message contains additional details to help diagnose the problem. For example, if the error occurred during the write-to-disk portion of the operation, the message states "error writing ...", specifying the name of the backing store file emake selected to receive the data and the OS error message for the failed write. If the error occurred during the read-from-network portion of the operation, the message states "error reading ...", specifying the type of exception that occurred and the OS error message for the failed read.
The list of possible causes for this error is virtually limitless: out of disk space on the emake client; a failed network connection to the agent; hardware failure of some sort; etc. Read the OS error message to determine the specific cause of the failure.
One way to estimate the amount of temporary space that emake requires is to look at the performance metrics that emake reports in annotation. In the annotation file, look for this value:
The diskWriteBytes metric represents the "high water mark" for the amount of temporary space emake requires to execute the build. Check that the temporary directory being used by emake contains at least this much space. For more information about temporary files, see "Managing Temporary Files" in the ElectricAccelerator Electric Make User's Guide.
Emake "g" debug logging may also provide some insight into the error.
This is truly an example of an "exceptional" error - one that in practice, should not be expected to occur at all. Most likely if it happens once it will not happen again, so a retry may be all that is in order. If the messages are occurring persistently, refer to the specific error message from the OS and reason about what could cause that type of failure. Searching for the OS error message using Google may turn up some clues.