I'm backing up about 750GB of data using a CDP to a dedicated server with 2x1TB drives. One of the drives switched to read-only when the last server was almost finish taking the backup.

My host is saying the following:
Most of the time when a file system goes to read only, it is caused ether by two much I/O such as having 3 servers backup at the same time to the same drive. Or the drive is failing, which I do not see any evidence to suggest that.
So should I ask to have the drives replaced or it's a normal thing that happens and when corrected it should not happen again for the same reason?

Please advise. Thanks.