A common issue when migrating to a new exchange version is the exhaustion of the log space resulting migration failures. Of course you can not simply go and delete those files because this will lead to more problems than the original one.
One migitation to this problem is to run a full backup in order to clear the files and release the space.The other way is to enable circular logging which can be done before you start the migration in order to prevent the problem from happening in the first place.
The migration procedure uses the Migration arbitration mailbox to store migration information and causes the transaction logs that fill up the disk.
You can find the name of the used arbitration mailbox and its database by the following powershell command:
“Get-Mailbox -Arbitration | ft Name,Database”
You can move those mailboxes to another Database and enable there the circular logging with the following command:
“Set-MailboxDatabase “DatabaseName” -CircularLoggingEnabled $true”
Happy disk space free migrations!!!!!