[mythtv] Ticket #6846: FreeSpace calculations don't work correctly

[Eric Bosch]

Thanks for your reply, Michael.  After reviewing docs on optimizing with
NFS, and changing a few options in /etc/fstab, /etc/mounts, apparently,
this brought the nfs reported size within the tolerance built in, and
viola, it now reports the correct information for available drivespace
and total space, etc.

Michael T. Dean wrote:
> On 08/15/2009 11:30 AM, Eric Bosch wrote:
>> MythTV wrote:
>>  
>>> #6846: FreeSpace calculations don't work correctly
>>>
>>> Comment(by sphery):
>>>
>>>  Is this fixed by #6582 ?
>> Ok, I just tried patch 6582 and that is still not returning the correct
>> results.  I think the correct way to fix this issue is to first
>> determine if the special directories actually reside on the same
>> physical filesystem (looking at results of df (mounted on column) or
>> Filesystem column.
>
> As Chris mentioned, it does.
>
>>   For NFS mounts, this might be a little more complex,
>> as the remote backend would have to determine the same results and
>> return them.  One issue I have with it is that the correction that is
>> built in for nfs mounts is not working properly either, in that the
>> reported size difference is greater than the correction.
>
> Ah, then that is the real problem.  The code assumes that any
> filesystems with a total size, available space, /and/ free space that
> are within 2MiB (or however much data can be written by the encoders
> within 5 seconds--whichever is greater) are the same filesystem.
>
> If your NFS server is returning a wildly-different value for any of
> these than the filesystem host's local access returns, Myth will
> assume they're different filesystems.  We increased the "slop factor"
> from 16kiB to 2MiB before 0.21 was released because of NFS
> inaccuracies ( http://svn.mythtv.org/trac/changeset/14924/trunk/mythtv ).
>
> Can you post the output of:
>
> df -k /path/to/storage/group/directory
>
> run for each of your filesystems used by Myth from each of your hosts
> "at the same time" (ideally when no recordings are being made/when the
> filesystems are mostly "not in use").  I.e. if you have a filesystem
> on the master that's NFS mounted on a remote backend, run the command
> on both systems as close to at the same time as possible.  And/or post
> the master backend log run with -v file,schedule,extra for the period
> when you hit the backend status page, as mentioned by Chris.
>
> Mike
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