[LAU] External USB 2 HD for real-time recording

Len Ovens len at ovenwerks.net
Sat Mar 9 18:15:46 UTC 2013


On Sat, March 9, 2013 9:49 am, Peder Hedlund wrote:
> Quoting Len Ovens <len at ovenwerks.net>:
>
> The previous reply was due to a trigger happy Send finger, sorry about
> that...

been there...

>>> An obvious workaround would be having a cron job doing a 'touch
>>> TempFile' or something similar on the disk once every 5 minutes or so.
>>
>> Would that actually touch the disk or just the copy of the temp file in
>> the ram buffers?
>
> Initially it would only hit the cache but I think it's be written to
> disk within the remaining five minutes.

I would guess it would depend on how busy the system was. I don't think it
would be high priority on a system running real time audio tasks. I don't
know enough about background disk writing to really say though.

> You could issue a 'sync' but I'm not sure a forced sync during, say, a
> recording would be the proper thing to do, since it syncs all cached
> data on all disks.

Ya that was my thought too.
>
> Another option would be to do a 'dd if=/dev/zero of=TestFile bs=1k
> count=1 conv=fdatasync' to make sure the data gets written to disk
> immediately (http://romanrm.ru/en/dd-benchmark).

Run in a script with sleep, not from cron which might be turned off for
recording :)  apt-get update running in the BG is enough to give me xruns
sometimes (I am not sure it is apt-get itself, but there is system disk
and network activity too)


-- 
Len Ovens
www.OvenWerks.net



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