Re: [LAU] Hard drive for "/" should be also 7200 rpm?

From: Robin Gareus <robin@email-addr-hidden>
Date: Mon Feb 20 2012 - 02:17:25 EET

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On 02/19/2012 09:56 PM, Yosef Werner wrote:
> Hi all,
>
> for testing reasons I've installed Arch-Linux on a second HD with 5400 rpm.
> The recording and production is on the first HD with 7200 rpm, openSuSE
> 10.2 and kernel-rt. After some work with Arch-Linux it seems that it could
> be the next platform for the DAW. My question is if a HD-7200 rpm is also
> necessary for the system to prevent x-runs? For sure, the HD-7200 rpm is
> mounted for recording.
>
> Thanks for sharing your knowledge,
>
> Yosef

Hi Yosef,

I short: No.

The system disk is completely irrelevant for audio-perfomance. Your
system will start faster with a 7200rpm disk mounted on root compared to
a 5200rpm drive of the same size but it has no impact on jack's
performance.

In fact the JACK x-runs are completely independent from any disk (even
the disk where your audio-data resides). I/O is never done in the jack
[real-time] context.
The jack-application (ardour, qtractor, jack_capture,..) will stutter
with with a message "Your disk is too slow!" if it can not read/write
fast enough [and the memory-buffers/cache are full]. It won't however
cause x-runs (other jack applications will meanwhile continue just fine).

Generally, HDD seek-speed is not very important for reading/writing
audio files. As Harry noted: most DAWs do buffer a few seconds of audio.

A somewhat conservative value: HDD reads/write speed ~20 Mbytes/sec:
  20 [MB/s] / 4 [bytes/sample] / 44100 [samples/second] = 118 [channels]
That's the theoretical maximum; yet real values are close to that.

You can measuere the speed and throughput of your disk width `hdparm
- -t`; or simply by copying a file while watching `dstat -D sda,sdb`.

HTH,
robin
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Received on Mon Feb 20 04:15:01 2012

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