[mythtvnz] Balancing free space after adding a recording drive

[Nick Rout]

On Sun, Jul 29, 2012 at 8:00 PM, Stephen Worthington
<stephen_agent at jsw.gen.nz> wrote:
> I recently was starting to run out of space for recordings, so I added
> another 3 Tbyte WD Green drive to my MythTV box and set it up as a
> recording storage group.  As usual after adding a new drive, most of
> the free space for recordings was on that drive and relatively little
> was left on the other three.  For MythTV to work best, it needs the
> free space to be spread around all the drives, so that it can record
> to as many of them as it needs to when recording many programs at the
> same time.  MythTV is pretty good at keeping the free space balanced
> during normal operation, if you use the normal settings.  It is only
> on adding a drive that this problem occurs.
>
> What I have done in the past is to do a directory listing of the old
> storage groups and edit that into a bash file of mv commands to move
> files to the new drive.  The problem with this is that you really need
> to only be moving files when there is no recording going on, as the
> heavy disk usage of copying can disrupt recordings.  So you have to
> guess how many files you can move before the next recording starts (or
> you want to watch something), and then put an exit statement in your
> bash file at the right point.  This is very difficult to judge, and if
> you get it wrong, using Ctrl-C to stop the script means you have to
> clean up carefully later as you may have a partially moved recording
> file that needs to be recopied,

I use rsync so I can resume and complete unfinished bits.

> or the *.png files matching a
> recording still need to be moved.

Actually I don't think they do need to be in the same directory as the recording


>So you normally need to get the
> bash file to log what is has done and not done.  And when adding a big
> drive, you have to do this many times over a number of days to get
> everything you need moved to the new drive - it takes quite a long
> time to move Tbytes of data, even with fast modern drives.
>
> So this time, since I was feeling like writing some code, I decided to
> write a script to at least semi-automate the process, and I have now
> got that working pretty well and my drives are all nicely balanced.
>
> It turned out to be not a bad bit of script, so now that it is all
> working, I thought that someone else might be in the same situation
> and could also use it.  It is a bit big for posting here, so I have
> cleaned it up a bit, and put it on my web server:
>
>   http://www.jsw.gen.nz/mythtv/balance_storage.sh
>

excellent, thanks!

> I am very much still learning bash, so if anyone does have a look at
> it, I would appreciate any comments about bugs, or better ways to do
> things.
>
> _______________________________________________
> mythtvnz mailing list
> mythtvnz at lists.linuxnut.co.nz
> http://lists.ourshack.com/mailman/listinfo/mythtvnz
> Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/