[mythtv-users] Basic? NFS question

[Chris Pinkham]

> Yes, the myth protocol uses a readahead buffer that gives you a
> local cache of data and is effecient when seeking. This should be
> more reliable than data transfered by NFS with no knowledge of the
> application needs. Some people guess that NFS might be better but
> that's not true.

Doesn't the readahead thread always run, whether you are streaming from a
remote backend or reading from a file locally (or via NFS)?

> It will look for the file name in the directory in RecordFilePrefix .
> If you are running a backend on this host, it will already be set.
> If not, mount the remote disk wherever it is convenient for this
> machine then run mythtv-setup and set that path on the second page
> of General as the "Directory to hold recordings".

This used to be the case, but was changed sometime after 0.18 I think.
The code now checks the backend's recording directory to see if the
file exists in that directory locally, so you shouldn't have to run
mythtv-setup and setup a local recording directory. If you do have
a local RecordFilePrefix configured, that directory will be checked
also.

> For me, I'd never read from a remotely mounted disk as a local path
> over using the application specific protocol.

In cases where you have a dedicated NFS server, using NFS can be
faster than the native protocol because using the native protocol
requires sending the data over the network twice.  The first time is
over NFS from the NFS server to the backend, then a second time via
the Myth protocol from the backend to the frontend.  It is more
efficient in this case to just read the file directly from the NFS
server.  This is one of the reasons I originally added code to
allow reading the file directly (via NFS, CIFS, etc.) if it existed
rather than using the Myth protocol, because I have used a dedicated
NFS server since I started using Myth back around v0.7.

For the case of a non-dedicated NFS server that is just sharing out
the recordings directory on the backend itself, then it may be better
to use the Myth protocol so I'll defer to your previous comments on that
case.

-- 
Chris