[mythtv-users] Spin up delay for HDDs

[Ramon Hofer]

On Mon, 26 Sep 2011 09:19:07 -0500
digid myth <digidmyth at gmail.com> wrote:

> I have 9 drives in my system with a 400 watt PS, see my configuration
> at http://www.gossamer-threads.com/lists/mythtv/users/492094#492094 I
> do not come close to the limits of the power supply on boot, so you
> should not have a problem.

Thanks for the info. It looks as if I could keep my PSU.
Btw: You boot your FEs with PXE. How long does it take to boot them?
I'm thinking of PXEing my FEs too.


> There is no need to use RAID with myth, Its built in storage groups
> work great. If you build that big of a raid how are you going to back
> it up? If I add a 2TB to my myth machine, I add a 2TB to my other
> machine to back it up to. The other advantage of not putting your
> myth storage disks in raid is that if you access one you only wake
> that drive up, not the whole raid. The drives will also have a
> tendency to last longer not in a raid configuration as they are
> sleeping most of the time. Think this out before you build a big RAID
> array.
> 
> It is not uncommon to have a drive in a raid fail, and another fail
> when it is trying to rebuild using a spare. Has happened many times.
> This is one of the reasons commercial raid systems do not use large
> drives. It takes less time to rebuild a failed drive with a smaller
> drive.  You did not say what size drives you are using, but if you
> are going with 2tb drives the time to build the raid is great. A 4
> drive raid 5 with 2 TB drives will take over 1 day to build, or
> rebuild. I have 2 2TB drives in raid 1 for my data, with a hot spare,
> but they are backed up to another machine, and the data is pretty
> static. A cron job backs up changed files one a day to another
> machine.
> 
> At work we have some very large raid 10 arrays but none of the drives
> are larger than 330G or so.
> 
> When I rebuild my myth server I will raid my boot drive/database
> drive, currently it is not a raid set.
> 
> The only data I have ever lost has resided on RAID arrays! I look at
> RAID as high availability, do not rely on using them as a way to
> backup your data. you still need to plan for backups, for the data on
> the RAID.
> 
> I have been using Storage groups for 2 years in myth and have been
> very happy with them. Personally I would not put myth video data on a
> RAID other than OTA recordings.

Interesting thoughts.

I have meant that RAID brings more safety and this would save me
from backing up...
What resync times concern: I already have a RAID 5 with four 1.5 TB
discs. It really takes a long time to rebuild it but this was no
problem for me.
For the new RAID I wanted to use 2 TB discs.

Thanks for your explanations.
I will consult my pillow again...


Cheers
Ramon