[mythtv-users] Hardware Setup Advice

Simon Hobson linux at thehobsons.co.uk
Wed May 23 13:53:34 UTC 2012


David Crawford wrote:

>However I'm sure there will be problems down the line as I have 
>another PC setup with windows software with the same hardware and it 
>encounters problems also when recordng many streams.

Your biggest issue will be disk seek times. Essentially, if you are 
recording 18 streams, then you have 18 threads which are syncing a 
file to disk once a second. This means the disk will be trying to do 
18 seeks & writes/second - and a cursory look at the specs of most 
disks will reveal that this is likely to lead to a bottleneck.
It's not the basic data rate that's the issue, it's the quantity of 
seeks that kills performance.

Adding additional disks, each in a separate storage group, will 
spread the I/O load across multiple drives and you should have a lot 
less of a problem.
Eg, if you add two more drives, then you'll end up with around 6 
streams/drive - if you can "about manage" now on 18, then around 6 
should be no problem. Even a second drive should help.

As for using a NAS, it depends very much on it's performance. 
Remaining polite, some NAS boxes "perform poorly", and it also varies 
with access method (SMB vs NFS vs AFP vs ...).

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.


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