Can't say for sure. I know that we have issued ALTER TABLE during backups, but I am not sure of the specific alter-ing that was done. We have also truncated, rekoved indexes, and creating clustered indexes while a backup was running.

To be thorough in disclosure, we do a verify/compare after the backup, but I am not sure we have recently done an actual restore. Last restore I recall was a year ago, and we restored the entire instance and Yosemite did that and finalized the restore for use successfully. I have no experience with restoring just one database for example. It is supposed to work the same, just I cannot personally testify to that.

>>We use Barracuda Yosemite Server Backup against a couple large SQL Server installations, one of which is being manipulated 24/7. Never had an issue.
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>Thanks
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>Have you tried to execute a similar command during the backup to see if it would work?