The database server cannot back up open transactions. If many transactions are active, the total logging activity should not force open transactions to the log backup files. For example, if your log size is 1000 kilobytes and the high-watermark is 60 percent, do not use more than 600 kilobytes of the logical log for the smart-large-object updates. The database server starts rolling back the transaction when it reaches the high-watermark of 600 kilobytes.