Hi @olivierlambert, Finally got round to following up on this. I found a better solution using DEFAULT_CHUNK_SIZE, which is normally set to 4MB, with MAX_PART_NUMBER being 1000, this limits the largest object backed up to 3rd party S3 implementations as 4GB. Increasing the DEFAULT_CHUNK_SIZE in the S3 code, or having a setting in configuration, either file or web GUI would allow backups of VMs larger than 4GB, without the memory required to track several thousand object chunks. Regards, Mark