[mythtv-users] Best options/howto for diskless frontends

Paul Gardiner lists at glidos.net
Mon Nov 26 12:22:23 UTC 2012

On 26/11/2012 11:46, Tim Phipps wrote:
> Quoting Paul Gardiner <lists at glidos.net>:
>> My hopes are (anyone of which can be dropped if it simplifies things):
>> 1) Not to have to add a disk to my Zotac ION.
> I would drop this and install a cheap SSD, I've tried NFS roots and it
> adds latency when going back to menus after watching programmes.
> Watching a programme tends to use up the local buffer cache so when
> going back to the menus the frontend has to fetch the text from the NFS
> server (which has also paged it out because it was serving the programme
> file). The same paging will happen with an SSD but it will be straight
> from disk to memory and not disk-memory-network-memory

Yes, maybe. I could probably live with NFS for now: I did with minimyth
for a long time. I'd prefer a ram based system if possible, but I'm
imagining that it would be very hard to cut down an opensuse
installation small enough to sit in 2GB of ram.

>> 4) To perform updates to the front end from the server. I'm
>> thinking chroot, but that might be impossible because my server
>> is running x64, where as I'm guessing the ION has to be 32bit.
> Your frontend will have to be shutdown while you do this otherwise there
> is a chance of it panicking when you change/delete the contents of
> programs/libraries. It doesn't damage anything but not nice to watch.

Oh yes, that's a good point. :-) Not a problem. The frontend is mostly
off when I'm fiddling. The thing that I'm expecting to be a problem
is the client running 32bit while the server runs 64bit. Am I right
that rules out some of the approaches to accessing the exported
client installation from the server?

>> 5) To be able to switch off the diskless machine without
>> shutting down.
> This is certainly easier with diskless booting, just hit the big white
> switch on the wall!

No risk of leaving the servers exported files in a mess?

> With an SSD you could run with a read-only root. Once you have the
> config sorted add "ro" to the /etc/fstab options for the root directory
> and reboot. I use this with Debian and once I'd figured out how to
> divert some files/directories to writeable NFS mounts or tmpfs it's
> fine. You need a tmpfs for /tmp, /var/run and /var/lock and either
> divert /var/log to /tmp or NFS. After that there are a bunch of files
> that need to be symlinked elsewhere but you will find those when you
> boot readonly.

Oh right! So no need for unionfs or anything complicated. Just a few
directories to target... although I worry that leaving unfinalised
stuff in /var/lock could cause problems... don't know really - I'm

Much appreciate the help, by the way, from both you and Per.


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