[mythtv-users] Adding another backend, and moving the master server to it?

Bruce Markey bjm at lvcm.com
Fri Aug 10 17:48:03 UTC 2007

Paul wrote:
> Dear helpful list,
> I have done a search on the archive, and looked around the Wiki but I
> still cannot decide the best way to accomplish what I am trying to do.

Always start with the HOWTO...

> (all machines are at same level, 20.current.atrpms stable)
> I have an existing master backend on my small server that does
> email/web/database the usual house stuff, with 2x DVB-T cards in it.
> I have just built a new machine that is in an Antec Fusion case under the
> TV, that will become my fixed front end, but also has 2x500GB disks in for
> storage (server has small disk capacity, well available to Myth anyway).
> I need to make the new server a backend as well as it will be getting a
> DVB-S card shortly for satellite.
> I will be keeping the two backends, as I do not have enough PCI slots in
> the new machine for all the cards, and I also have dedicated feeds from

Good. For some reason, people seem to be attracted to the
idea that it is somehow really cool to have lots of cards
in one machine. This is not a good objective. Many resources
come into play so more motherboards, PCI buses, PCI slots,
disk controllers, disks, CPUs, etc. all help. Adding more
cards to one host is not very scalable, however you can have
several machines with two cards or less and avoid resource
contention issues.

> the TV aerial to the cards in the existing server making reception good.
> If they went under the TV they would need to be split form the same feed
> which would affect some of the weaker channels.
> Questions:
> 1. Is there an easy way to move the database and main backend onto the new
> machine? (it has a Ahtlon X2 45w CPU, and is much better suited to
> commflag than the 1.7g celeron in my little server, more memory too).

First, you need to be sure that the mysql server on the new
host will accept remote connections.


Stop your myth* process then dump and restore your database
to your new host.


Stop your old mysql server so there will be no confusion of
connection to the old db rather then the new one.

Update your mysql.txt files to point to the new database.

Start your backends and frontends verifying that each is
connecting to your new db.

> 2. Should I leave things as they are and upgrade to 0.21 with storage
> groups to allow me to add the new space into the current system?

Multi-disk filesystems are a good idea for writing random
small files in parallel. However, the best way to continuously
append to single large files is to leave the heads positioned
and let it stream without the heads thrashing to multiple
locations. Therefore, Storage Groups are a big win when you
have multiple cards and multiple disks on a hosts.

You have two new 500GB disks that you haven't used at all to
this point. I'd suggest that you mount one of them as the
RecordFilePrefix dir for your current myth version. You are
not going to fill up 500GB in the next few weeks =). When
you upgrade to a version with SG, mount the other disk and
add it to your Default storage group. At that point, all your
existing files will be available but now the system will be
able to use the other disk too.

--  bjm

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