Lock-Optimization for archived MyISAM tables

Lets say we have 100GB of data stored in MyISAM tables. 90GB will never be changed (archived tables) and 10GB are changed every minute.

-> Backup will lock all tables for ~10 minutes and also replication will have some delay.

I made some modifications to the innobackupex-script (used with parameter --checkfiles) so that it will first copy all tables (~10 Minutes), then lock all tables und recopy only changed tables (10GB) in ~1 Minute.
-> Backup is 10% slower but table-lock is also minimized to 10%

So you only have to save some file-information like ‘date changed’ and ‘filesize’ for every file you copy - and on second copy you simply compare that filesizes and dates on the local server (not as rsync does on the remote side).

I did that for cp and scp (remote-host)… works quite well.

An alternative approach would be to make innobackupex release a lock to a certain table as soon as the files of that table are copied. If you could make it backup the active tables first, you have the same downtime but not the extra minute delay.