[mythtv-users] Wake up disks on events

Jon Boehm boehm100 at comcast.net
Thu Aug 21 00:07:00 UTC 2008



mythtv at blandford.net wrote:
> Hello,
> 
> This is a little off topic, but I am hopeful I will get some good ideas.
> 
> I have a few mythtv frontends running minimyth as well as a fedora  9 
> backend+frontend combination.
> 
> I use hdparm to spin down the mythtv disks when they are not in use.
> 
> This is working really well for the most part.  The power consumption of 
> my server goes from 185W to 130W when the disks spin down.
> 
> When I power on a frontend and watch a show, it takes 10-15 seconds for 
> the disks in the backend to spin up.  this causes the frontend to appear 
> to freeze.
> 
> What I would like to do is add some hooks to help control the disks.
> It might be a single daemon or just cobble several things together.
> 
> Here were my thoughts:
> 
> 1) A frontend hook to notify the server to wake up the disks.  The 
> frontend could ping a certain port on the server, or touch a file on the 
> server to notify it was awake.  The disks will wake up in the time it 
> takes the TV to warm up.
> 
> 2) Wake up 1 minute prior to recording any shows.  I miss 10-15 seconds 
> now.  I don't want to tell mythtv to record an extra minute early 
> because it causes show overlaps in the scheduler.
> 
> 3) Check the upcoming recordings and keep the disks spinning if another 
> show is starting with X minutes.  Don't spin down the disks if they are 
> used again soon.
> 
> 4) Schedule the database optimize, myth_rename, updatedb, etc 
> immediately after the last recorded show of the day so the disks won't 
> wake up in the early morning to run those tasks.
> .
> 
> Has anyone else done something like this or do you have suggestions on 
> any of these?
> 
> Michael
> 

I use cron to set my drives to spin down after 20 min between the hours 
of 1am and 7:30pm.  The majority of my programs are recorded during 
primetime and my viewing is usually during this time also.  On off hours 
recordings, I notice a video glitch about 5 seconds into the recording, 
like a buffer overflow as the drive spins up.

Eventually I would like to use the serial comm connection to my AV 
receiver to trigger drive spin up.  I don't know enough about Linux and 
serial ISRs yet to do this.

Jon


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