For some reason the backup started running very slowly. It used to take around 7 hours and now it takes almost 24. The only change that happened recently was moving the mailbox store and some user data onto a different disk in the array. The backup was reconfigured since and even tested by selecting only the old disk with no difference. When leaving the backup it succeeds in the end. The backup log shows that the backup which was supposed to run according to the schedule fails in the meantime as other backup is running. Not sure if this is OK as you would thing the backup should just skip to the next scheduled time. Anyway, any ideas what could be the reason of it running so slowly?