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

Mike Perkins mikep at randomtraveller.org.uk
Wed Sep 28 16:21:53 UTC 2011

On 28/09/11 17:15, freedenizen wrote:
> On Wed, Sep 28, 2011 at 9:11 AM, Eric Sharkey<eric at lisaneric.org>  wrote:
>> A drive like that should handle about 75MB/s. Â A typical HD recording
>> from cable is about 5GB/hour, which works out to less than 2MB/s.
>> I think you'll be fine.
> I disagree, with the db and os on the drive the issue isn't sequential
> io, it is random io.  Remember that the drive will be reading and
> writing to the db while doing all those recordings.
> I'd recommend getting another drive for the OS/DB, once you do that
> you should be able to handle a large number of recordings on your 2TB
> drive.
Even that might not be enough. Recording four things at once on the same drive 
means the head is going to be seeking to four different places all the time... 
plus the system areas as it updates the file extents. Not good.

It makes more sense to spread your recordings over more than one disk. One disk 
per simultaneous recording is what you ought to be aiming for, the head movement 
is negligable in that case. Not to mention, with storage groups the number of 
disks is immaterial, plus if one fails, you don't lose everything.


Mike Perkins

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