The snapshot process is complex and can fail, especially when dealing with busy Cloud VPS's with large disks.
A snapshot is composed of one or more large files that are split into parts to overcome the 5GB object size limit of the object storage. Every part is verified using a hash and only when all the parts are stored and verified is a special file called manifest created so it can be used to retrieve all the parts assembled as one single file. Finally, when all the files are uploaded, a README.txt file is created with some control information that can be used to verify the snapshot.
In some exceptional cases when a snapshot fails some files may be left behind for our support team to analyse. These snapshots will be listed as broken in the table of recent snapshots and can be deleted safely. A broken snapshot will never be used to re-image a server.
We can't reliably detect broken snapshots while there's a snapshot in progress, so take that into account and please wait until any ongoing snapshot is finished before looking for old snapshots to delete.
Should you snapshot fail the status will show as "ERROR" if you are unsure on what to do or need assistance, please do open a ticket with our Technical Support Team.