[mythtv-users] Spin up delay for HDDs

[Raymond Wagner]

On 9/25/2011 11:35, Ramon Hofer wrote:
> Hi all
>
> I'm planning to upgrade my backend server with a 8 disc RAID.
> I'm not yet sure if I need a RAID6 or if a RAID 5 is enough.
> Any thoughts?

With 8 drives, I would personally go RAID6.  With that many drives, 
you're just looking at that much higher risk for failure.  Better to 
have the extra redundancy.

> I'm concerned about my PSU. It's 460 W and in my server are already
> 6 HDDs.
> My idea was to delay the spin up of the HDDs.
> I have a Netgear ReadyNAS which spins up the discs one after the other.
> Google couldn't tell me how to do this manually. I only found that some
> HDDs have jumpers that can be set to delay the spining up.

What you're talking about is called Power Up In Standby.

http://en.wikipedia.org/wiki/Power-up_in_standby

My RAID card has an option for staggered spinup, but I've never seen 
that option in any other hardware.  On the handful of drives I have that 
support it using a jumper, attempting to do so simply resulted in them 
not being recognized by the card.  Right now, I've got a 650W power 
supply for fourteen drives, the RAID card, 4G of DDR3, and a dual core 
Phenom II.  With all drives spun up, I'm pulling maybe 150W, but I've 
just barely enough power to boot.

A previous incarnation used an old, power hungry, dual core Opteron, 
with 2GB of DDR1, Geforce 6500, and the same drives and RAID card.  With 
the increased draw from the processor, memory, and graphics, the drives 
were starved and not all would spin up.  I frequently would have to 
manually stagger the startup using the power buttons on the front of my 
hotswap bays.



If you've got a bit of electronics capability or inclination, you might 
want to check out this project.

http://www.flickr.com/photos/linux-works/4320933179/

It uses a little microcontroller to manage staggered spinup from a 
series of relays, and hooks into your motherboard reset button to 
prevent it from POSTing until the hard drives have finished doing their 
thing.