Online backup to an object service using bulk export

A system and method for improving storage system performance by maintaining data integrity during bulk export to a cloud system is provided. A backup host reads a selected volume from the storage system via an I/O channel. The storage system remains online during bulk export and tracks I/O to the selected volume in a tracking log. The backup host compresses, encrypts, and calculates a checksum for each data block of the volume before writing a corresponding data object to export devices and sending a checksum data object to the cloud system. The devices are shipped to the cloud system, which imports the data objects and calculates a checksum for each. The storage system compares the imported checksums with the checksums in the checksum data object, and adds data blocks to the tracking log when errors are detected. An incremental backup is performed based on the contents of the tracking log.