Brian from Backblaze here. If you use b2_list_file_versions (or any of the b2_list functions) there are checksums included in that list (SHA1). When you ask f

Brian from Backblaze here. If you use b2_list_file_versions (or any of the b2_list functions) there are checksums included in that list (SHA1). When you ask for that file list, the results are actually coming out of a large Cassandra cluster (database with many computers and fast SSDs). Ok, so even if you do not request a file list of any kind, Backblaze itself automatically is always walking over the entire data farm checking every single last file's SHA1, plus checking if the files match the database's SHA1. A full sweep completes in less than a month then begins again. If any bit error is detected (which happens semi-regularly since we have over 72,000 hard drives and bits get flipped) then we rebuild the files from the other copies (Reed-Solomon encoded across many separate computers in many separate locations in our datacenter). We love and take care of your data so you don't have to.