[mythtv] mutliple storage directories idea... ?

[Bruce Markey]

Michael T. Dean wrote:
...
> Line 1222 of programinfo.cpp is the culprit, but unfortunately, I can't 
> see an easy way to fix it.  We can't just trim the RecordFilePrefix off 
> the left because it won't work with multiple hosts...

You don't want to allow a server to access to any arbitrary full
path.

> I can't think of a non-invasive approach to use.  Ideas?

Here's what I've written before that I'd like to see but I haven't
needed this so far so I'd never gone past some simple proof of
concept tests last winter.

--  bjm

-----------8<-----------8<-----------

Even though I still don't need this myself, I did start on
a prototype back in Dec. that allows a colon separated list
for RecordFilePrefix. It correctly splits, reads from and
writes to any of the dirs. Reading from the dirs throughout
the code is pretty easy. For writing, I'd like it to make
these choices:

- prefer not full (above MinRecordDiskThreshold) over full
- prefer local disk over remote mount
- prefer a disk not in use by another recorder over one in use
and if there is still more than one equal choice,
- prefer the disk with the most free space

The remaining problems are determining that a dir is on a local
mount vs any type of remote mount (NFS, Samba, others?). Also
determining which backend is responsible for a directory if it
is shared for reporting total free space properly and which
backend(s) may delete files. This isn't too bad if all NFS
mounts are from disks that are local to another backend, The
local backend would be responsible. However, if one of the
dirs is a disk on a slave and that slave is down or if there
is a shared NFS mount from a system that doesn't run a backend,
exactly one backend has to take charge for that disk.

If this all works, you can have more than one disk on a machine
whose filesystems are not tied together so you can move files off
one to take the disk out, replace it or do maintenance. A slave
could have a local disk and paths to NFS mounts so if the local
disk fills up it could fail over to writing across the network.
A master could have paths to NFS mounts of the slaves' local
disks so the master could play the slaves files even while the
slave backend process is not running (but the machine would have
to be up of course =). Etc.