My understanding is mysqlhotcopy works very similar to rsync.
In one of our servers backing the database file using rsync takes about 15 minutes for 50GB data.
Backing up the same data using mysqlhotcopy takes about 30 minutes.
How come mysqlhotcopy is significantly slower?
rsync does not have any MySQL-specific gotchas to watch out for. rsync can copy literally anything with impunity.
mysqlhotcopy has to watch for opportunities to lock files which could delay actual start time for copying.
I wrote an earlier post contrasting rsync and XtraBackup along this line of reasoning
I also wrote a post on how to copy using rsync on a running mysql server with relative brief downtime.
Here is post I made in ServerFault
Here is still another post in ServerFault, with sample code !!!
