[mythtv-users] Wiki: Balanced Disk I/O

[Jay Foster]

On 8/11/2015 8:48 AM, Peter Bennett (cats22) wrote:
> Hi MythTV experts
>
> I am updating the wiki and wondering about the Balanced Disk I/O setting.
>
> https://www.mythtv.org/wiki/Storage_Groups#Balanced_Disk_I.2FO
>
> The above page recommends if you are doing more than 2 recordings at 
> once to use this setting to get recordings put on separate file 
> systems to avoid buffer overruns. I am thinking of changing that 
> recommendation.
>
> A quick back of the envelope calculation tells me that I could record 
> some 50 HD programs at the same time on one disk drive, based on 1 
> Gb/sec transfer rate and 8 GB per hour on each HD recording.
>
> Clearly 50 at a time is theoretical and unlikely because it would be 
> affected by seek times. However HD programs vary from 3 GB to 8 GB per 
> hour which means even more than 50 at the same time.  Also drives are 
> rated at 6 Gb/sec which means 300 HD recordings at the same time(!).
>
> You could surely record at least 10 HD programs at the same time or 
> maybe many more, so unless you have a very unusual situation it seems 
> that you need not concern yourself about hard disk performance.
>
> I have 6 tuners and have never had a disk performance problem, even 
> while watching at the same time as recording, but I have probably not 
> recorded 6 channels at once.
>
> Does anybody have an opinion on this?
>
> Peter
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://lists.mythtv.org/mailman/listinfo/mythtv-users
> http://wiki.mythtv.org/Mailing_List_etiquette
> MythTV Forums: https://forum.mythtv.org
I have recorded 5 HD programs at the same time while watching another 
with no problems (HD homerun).  I only have a single recording drive, 
but do have the DB on a separate drive.  The statement, "drives are 
rated at 6 Gb/sec", depends on the drive and the system.  SATA III 
drives are (when used with a SATA III controller), but SATA II drives or 
IDE drives, or other drives are not.

Jay
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20150811/0e567fbe/attachment.html>