[mythtv] Preemptive Disk Writes

Christian Hack christianh at edmi.com.au
Sun Oct 24 08:21:48 UTC 2004

> -----Original Message-----
> From: mythtv-dev-bounces at mythtv.org 
> [mailto:mythtv-dev-bounces at mythtv.org] On Behalf Of Dan Morphis
> Sent: Sunday, 24 October 2004 5:38 PM
> To: Development of mythtv
> Subject: Re: [mythtv] Preemptive Disk Writes
> On Sat, 23 Oct 2004 22:24:10 -0400 (EDT), Eric M. Reischer
> <emr at mercury.ccil.org> wrote:
> > Just a thought I had after setting up my mythbox (package 
> is awesome by
> > the way).  Since I have a brand new 120 GB disk and I want 
> it to last
> > awhile, I set up noflushd to spin down the disk after an hour of
> > inactivity.  I've noticed, however, that my programs tend to start
> Statistically speaking, your drive is way more likely to fail on spin
> up, than in the middle of spinning at full speed. All the drives I've
> ever had which failed, the cause was a failure to spin up.

That's not at all what he's talking about - perhaps you were just giving a
heads up though? He's talking about the fact that while the drive is
spinning up it's not recording since the buffers fill up very quick. I have
similar issues due to my LVM setup where drives spin down and then need to
spin up in the middle of recordings causing IO blocking and lost frames.
This is not a MythTV problem though and really is a kernel problem not
buffering and blocking while waiting for a drive to spin up.

As for your comment about drives failing on spin up, yes I agree they
generally fail on spin up, but that's not necessarily due to being spun
down. Rather it's due to the drive motor/electronics failing. Not spinning
down a drive is merely delaying the inevitable if the drive is already on
the way out. Spinning it down will help particularly if the drive won't be
accessed for long periods. Frequent spin up/down cycles could be detrimental
though. I can see discussion this getting out of control - if you want to
continue, please move this discussion to -users list or even off list.


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