[mythtv-users] Basic? NFS question

Mario Limonciello mario.mailing at gmail.com
Thu Feb 9 13:12:04 UTC 2006


On Thu, 2006-02-09 at 02:06 -0500, Chris Pinkham wrote:
> > 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.
> 

I really think someone should add this info to the documentation, or at
least the wiki for that matter.  I have been curious about this for
ages, just always have forgotten to ask.



More information about the mythtv-users mailing list