...and can I convert all tables to InnoDB without breaking ispconfig? The reasons to ask are two: 1. On mysql crash tables can be corrupted and must be checked. It happened to me once. 2. I want to use Percona XtraBackup, but I have a problem, which may be caused of MyISAM tables (I think it completely locks MyISAM tables during backup, which can take long time)
We use myisam as it works better in our tests, is faster and makes less problems with recovery and as ispconfig does not require any of the functions from innodb, there is no reason to switch to innodb. If you want to convert the tables on your server, then you can do that. It will not break ispconfig.
I'd be interested in doing it for referential integrity, but I'm not quite sure I want to piece together all the implicit foreign key relationships myself MyISAM may be a little faster depending on your queries but you can never be sure it's consistent, especially after a recovery. I daresay an InnoDB database that doesn't recover cleanly despite its log would have sustained some more or less subtle damage if it had been MyISAM.