If I look in the Primary Database Maintenance Plan History it shows no failures though it only appears to be showing a backup transaction log and delete old transaction logs activity, nothing mentioning copies or restores. Am I missing something?
OK, after trawling many threads I came accross something mentioning a copy delay (the delay between the Primary backing up its transaction logs and the secondary copy them). Initially all jobs were being triggered to run at the same time (There was no copy delay) I changed the sequence so their were 30 second gaps between the three jobs. This seemed to have instant results and the copy job was no longer failing.
Cut to this morning and a quick check on things and about 5 percent of the job runs have failed. A quick comparrison of the backup and copy job histories show that the copy failed whenever the backup duration was over 30 seconds. Hopefully this proces the point and all I need to figure out is the maximum backup time so I can work out the optimum copy delay.