Problem: CephFS fallocate implementation does not actually reserve data blocks when mode is 0. It only truncates the file to the given size by setting the file size in the inode. So, there is no guarantee that writes to the file will succeed Solution: Since an immediate remediation of this problem is not possible, I request users to vote on the most suitable approach to avoid breaking dependent software: 1. report EOPNOTSUPP (operation not supported) when mode is 0 2. continue with existing implementation of file size truncation when mode is 0 -- Milind _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx