Hi Lennart, On 2015-02-16 23:59, Lennart Poettering wrote: > * journald now sets the special FS_NOCOW file flag for its > journal files. This should improve performance on btrfs, by > avoiding heavy fragmentation when journald's write-pattern > is used on COW file systems. It degrades btrfs' data > integrity guarantees for the files to the same levels as for > ext3/ext4 however. This should be OK though as journald does > its own data integrity checks and all its objects are > checksummed on disk. Also, journald should handle btrfs disk > full events a lot more gracefully now, by processing SIGBUS > errors, and not relying on fallocate() anymore.
If I read correctly the code, the FS_NOCOW is a temporary workaround, i.e. when the file is closed (or rotated ?) the FS_NOCOW flags is unset again. It is true ? If so, the time window where a file is un-protect by the checksum is quite small. I was worried not about the corruption detection but about loosing the ability to recover the file from a good copy (if available) in case of corruption. But this seems limited only when the file is in use (before the next rotation). BR G.Baroncelli -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5 _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel