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

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To: linux audio users <linux-audio-user@...>
Date: Saturday, March 9, 2013 - 5:01 pm

On Sat, March 9, 2013 4:30 am, Ralf Mardorf wrote:

> an external hard drive does spin down too often for my taste. It's a

So far as i can tell mine doesn't, but then mine is a case I added a drive
from an old laptop that stopped working. BTW this is not the drive itself
but the USB board... Or if it is the in the drive itself, it would be the
same if the drive was used internally.

> Regarding to a German PDF SmartWare doesn't support this particular

So all you need is to provide disk activity every 8 or nine minutes...
sync or something. I am not sure but I don't know how bad sync is at
grabbing system resources and if there are a lot of full buffers this
could take some time to complete.

> Is there a way to adjust this feature? I fear that spinning up and down

I don't know if this would cause an early fail, but from the
manufacturer's POV, so long as it is past warranty that is a good thing :P

> Is it possible to use such drives for recording, without any risk? If I

This is a hard issue, because I have 2.5G ram. My OS and all the apps I
use for recording take up maybe about 1G (cause I was able to record when
I only had 1G). So there is 1.5G worth of ram that can buffer data going
to coming from disk. I might be able to record several tracks without ever
touching the drive. So to test this you have to have enough tracks to fill
ram buffers and force write to disk. Now when tracking, normally I am
reading a bunch of tracks and only writing one or two. Reading takes less
system resources than writing (I think... requires inode writes at least)
so if the system is smart it will off load the reading first. Once it does
that your drive will stay spinning, so the write part will not induce a
spin up... anyway to test you need something that is on the verge of
needing real disk access. Memory almost full and then record till the
drive works. I am assuming the drive is only used for audio and no system
commands would touch it.

> This drive should be used as a backup media only, but I'm thinking to

Sounds like fun :) now the amount of ram in an unknown system comes into
play. Assuming you are taking a USB audio IF, then USB irqs have to be
looked at before deciding where to put the IF, USB stick and drive (DVD
might in this case be better than USB stick, though the USB sticks seem to
be more reliable). I personally have not had any problems a USB drive
being in a USB port that shares irqs while recording, but I can not say
for sure that a write or read was forced while I was recording.

Len Ovens

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Messages in current thread:
Re: [LAU] External USB 2 HD for real-time recording, Len Ovens, (Sat Mar 9, 5:01 pm)
Re: [LAU] External USB 2 HD for real-time recording, Ralf Mardorf, (Sat Mar 9, 5:46 pm)