[mythtv-users] disk full, can't delete files

Michael T. Dean mtdean at thirdcontact.com
Wed Nov 11 02:57:01 UTC 2009

On 11/10/2009 07:43 PM, Chris Adams wrote:
> What is the minimum free space set to out of the box? Can I suggest it
> be defaulted to something sensible (for our modern world of terabyte
> hard drives), perhaps 1-2GB?
> I have no idea where this would be set but if someone can point me in
> the right direction I'll be happy to supply a patch..

It's set to 1GiB by default, but depending on configuration, this may 
not be enough extra space to allow Myth to react in time when the system 
has multiple and/or high-bitrate recorders.

And, even for a single, low-bitrate recorder, if the filesystem has its 
own limit on it (the reserved space allocated by most file systems), the 
"Extra Disk Space" setting needs to be set to a value greater than the 
amount of reserved space.  For example, ext2 and ext3 (and likely ext4) 
allocate 5% of the file system as reserved blocks only usable by root.  
1GiB is 5% of 20GiB, so on a larger file system, it may be "full" long 
before you hit that 1GiB point.  Since most hard drives are very large, 
increasing this value to sufficient size to handle reserved space that 
/should/ be enabled on all root file systems would make the initial 
value huge--if you assume the average hard drive used to contain a root 
file system is only 160GB, we're talking 8GB, for 320GB it's 16GB, and 
so on.

However, I don't think increasing the default is a good idea.  For those 
who do have dedicated file systems for MythTV recordings, they're often 
created (or tuned) to have 0 reserved space.  And, since the "Extra Disk 
Space" setting in MythTV applies equally to all file systems used by 
MythTV, we're actually reserving "Extra Disk Space" x number of file 
systems, so it adds up fast when larger values are used (16GiB with 5 
file systems is 80GiB--enough for >10hrs of ATSC HDTV or 40 or more 
hours of SDTV).  The value it currently uses is reasonable for a 
dedicated partition--which is what most people use (possibly after 
having issues with using the root partition :).


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