[mythtv-users] How many simultaneous recordings on one drive?

jedi jedi at mishnet.org
Wed Sep 28 23:32:26 UTC 2011


On Wed, Sep 28, 2011 at 11:28:10PM +0100, Simon Hobson wrote:
> Eric Sharkey wrote:
> 
> >Four recordings at 2 MB/s is 8MB/s.  The buffers on these drives are
> >usually 32 or 64MB.  They can seek at almost 100Hz.  It just won't be
> >a problem.  You've got a 1996 mind set here.
> 
> They may have large buffers, but then Myth is actively syncing each 
> record stream every second. I believe that should have the kernel 
> sending the write requests to the disk AND waiting for confirmation 
> that they've been written. That's immediately added several 
> seeks/second to write each stream plus the filesystem data.
> 
> Also, something not mentioned, if you are commflagging then that can 
> impose significantly higher I/O loadings than just streaming 
> recordings on/off disk.

    Yup. I tend to reign in commflagging a bit during prime time viewing
hours. Otherwise, recording multiple streams and then flagging them on a
single drive accessed by most machines across the network (GigE) hasn't 
been a problem.

[deletia]


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