The minimum billable size for IA and Archive objects in OSS is 64 KB. Objects smaller than 64 KB are charged as 64 KB. Therefore, if a bucket contains a large number of objects smaller than 64 KB, the billed storage usage of IA and Archive objects may be greater than their actual storage usage.
You can view the actual storage usage and billed storage usage of IA and Archive objects on the Overview page of corresponding buckets in the OSS console. For more information, see Bucket overview.