[mythtv-users] Moving my mysql database to another drive

R. G. Newbury newbury at mandamus.org
Mon Jan 24 15:01:38 UTC 2011

On 01/23/2011 01:12 AM, Michael Rice wrote:
> I am having some problems that may be related to disk performance.
> (See http://www.mythtv.org/pipermail/mythtv-dev/2011-January/070387.html).
> I have an extra drive and I am thinking about moving the database to it
> to see if it helps the situation.
> If anyone has pointers/gotchas on doing this (especially on Fedora)
> I'd appreciate hearing about them.  Is there any particular way I
> should format the drive to help performance?

There is a section in the myth documentation which sets out the steps 
required to move the database. That section looks more at moving from 
one machine to another. In your case, you are only moving the files from 
one mount point to another.

I have run myth on fedora for a number of years with the files on a 
different partition than the mysql server thinks they are, by making the 
usual file tree site a soft link to the new spot, ie:

service mysqld stop
mkdir /home/mysql				# or wherever...
rsync -avu /var/lib/mysql/*  /home/mysql	# make the copy
chown -R mysql:mysql /home/mysql		# compel ownership
rm -rf /var/lib/mysql				# remove old spot
ln -s /home/mysql /var/lib/mysql		# trick the mysql server
service mysqld start

The mysql server continues to think that things are at /var/lib/mysql 
while the OS slips in a substitution.

In your case, you will want to create a mount point for the new file 
tree, on a different drive, first.

You might want to consider moving your entire /home tree to that drive 
anyway, so as to keep it entirely separate from the rest of the OS. 
(Makes re-installs much easier!)

As to formatting, you want a filesystem optimized for dealing with many 
small files (as distinct to one with a few large files). I do not think 
that there are disadvantages to just using ext4. Under the 
circumstances, I am not sure that having journalling can actually help 
much, but I understand that it has no speed disadvantages, so I would go 
with that.


              R. Geoffrey Newbury			

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