[mythtv-users] Changing mythconverg tables to use MEMORY a opposed to MyISAM?

Matthew McClement mythtv at macker.co.uk
Thu Oct 25 12:56:10 UTC 2007


Ben Lancaster wrote:
> Hi all,
> 
> Has anyone experimented with changing the table types of some  
> commonly used tables in mythconverg to use MEMORY rather than MyISAM?  
> In an attempt to reduce disk noise, I was wondering whether this  
> could be a worthwhile approach? Obviously, there's corruption issues  
> in case of power failure or MySQL server crashes, but I haven't had  
> either in years

I've put the mythconverg database into a tmpfs filesystem which had a 
master-master replication setup to a remote MySQL database that was disk 
backed. The startup script on the backend would connect to the disk 
backed master, get a dump of the database and restore it before starting 
replication back up again.

Not that there seemed to be much point in the end. The tables that are 
the busiest I/O wise also tend to be the more important so you're going 
to have to back them to disk somehow. There was little in the way of a 
performance improvement and just made the setup more complicated. Also,
keep in mind MEMORY tables don't even survive a MySQL restart.

Generally you're far better off just optimizing MySQL to use some of 
your spare memory and/or playing around with some of the stuff in /proc 
to make writes more lazy when it comes to committing to disk.

Matt


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