Code review comment for lp:~sergei.glushchenko/percona-server/ps56-univ-log-archive

There is an issue with archived file number and archived file offset. These values are written to checkpoint as 4-byte values, however they are naturally 64-bit (type of archived_offset/next_archived_offset should be changed to lsn_t as well).
Possible solution is not to write archived file number to archived file header and to checkpoint. Archived file number is the same as first LSN for archived log file.
I'm going to implement this and look how it goes.