[mythtv-users] disk load balancing with slave BE over nfs

Andre mythtv-list at dinkum.org.uk
Fri Aug 20 08:00:41 UTC 2010


On 20 Aug 2010, at 08:20, Chris Pinkham wrote:

> * On Thu Aug 19, 2010 at 01:57:50PM -0400, Michael T. Dean wrote:
>> On 08/19/2010 06:23 AM, Andre wrote:
>>> A small but very significant question about disk load balancing that I 
>>> can't find an answer for anywhere.
>>> 
>>> I'd like to make my current Slave BE/ Remote FE diskless and shutdown when 
>>> idle but I'm concerned about how the disks will be loaded during 
>>> simultaneous HD recordings, I find that MythTV is very sensitive to 
>>> multiple HD recordings to the same disk when the disk is full, which of 
>>> course it always will be :-) I'm using 0.23-fixes on 32bit Ubuntu 10.04 
>>> with 6x XFS sata disks (2x500G, 4x1.5T), using the recommended xfs mount 
>>> options and nfs options from the wiki.
>>> 
>>> I see that MythTV detects if an nfs mount on the slave is the same disk as 
>>> the master, mythweb status shows this well.
>>> 
>>> What I'd like to know is if the slave and master are aware of each others 
>>> disk usage, does the master backend tell the slave which disk is best to 
>>> use or the does the slave decide that independently with no knowledge of 
>>> the masters usage?
>> 
>> TTBOMK, both know when the other is using a file system.
> 
> A little more detail....
> 
> The slave only knows what he is told.  The master knows about what disks the
> slave can see and he tells the slave where to record next by supplying the
> directory name in the scheduled recording info he sends to the slave.  The
> slave knows nothing about any storage other than his own and during normal
> scheduled recordings, he makes no decisions on his own.  The only time a
> slave makes a decision as to what disk to use is during LiveTV _IF_ the
> slave asks the master where to put the next LiveTV file and the master does
> not answer back in time.  In that case, the slave decides to use the disk
> that he can see with the most free space.

Very detailed and precise, thank you.

I can switch to nfs mounts only on my slave be with confidence that the spindles will be efficiently used.

Live TV won't be an issue, not something I've ever used.


Thanks.



> --
> Chris
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