I use Backup Assist to perform backup our Hyper-V instances we use for our development machines (code repositories, bug tracking, test databases etc). This morning I arrived in the office to find the backup had failed overnight, with the following error:
Backup stopped before completing.
ERROR - Volume Shadow Copy Service operation error (0x800423f3)
The writer experienced a transient error. If the backup process is retried,
the error may not reoccur.
Nothing had been changed on the Hyper-V server, any of the Hyper-V instances or Backup Assist, so I was shocked that the backup just all of a sudden failed with a cryptic error.
I started googling and all I could find about this error was a hot fix which resolved the issue. I was sure the hot fix wasn’t going to do squat as the backup was working yesterday. So before looking further into the hot fix I decided to have a poke around my Hyper-V server and instances to see if there was anything obvious.
After about 1/2 an hour of looking into the event logs or each machine etc I found one Hyper-V instance had only 100megs of free disk space. Surely that wasn’t causing the backup to fail? So I freed up some space so it had a gig of room free and now the backup is working!
Moral of the story, always make sure your Hyper-V instances have a reasonable amount of free disk space and if you get the error above, your more than likely run out of space somewhere.