[mythtv-users] Optimal disk configuration for MythTV?

[Mike Perkins]

On 27/12/12 18:35, Jelte Veldstra wrote:
>>
>> 2x Large capacity hard drives in RAID 1 for Myth Video, torrent server, and
>> fileserver.  There is some stuff on here I don't want to lose so RAID is a
>> must.
>>
>
> Please note that RAID != backup. While it can save you trouble when
> losing a single disk, it will not save you when you (accidentally)
> delete files or have some process corrupting data or the filesystem.
>
> Your reasoning totally makes sense and at the end it is also personal
> preference. Here's perhaps a different approach: Years back I also
> used on RAID on my backend system. Then I realised the total power
> consumption of all these drives. Now I'm back to a two disk setup
> where one is spinned down all the time. Every night a rsnapshot job
> wakes the second drive up and copies the important stuff to it after
> which it can spin down again (another rsnapshot job copies it over ssh
> to a Linux host 10 miles away from me for offsite backups). For me the
> advantages are less power consumption (one idle green drive and a spun
> down drive take up about ~6W total) and rsnapshot keeps multiple
> copies, so even when a file gets corrupted or had multiple edits I can
> recover further back in time (12 weeks in my case). Should the number
> of concurrent recordings increase I may decide to add a 1TB laptop
> drive to cope with the increased IO. That extra drive can be spun down
> as well only to come alive when a recording is done or played back.
>
Be aware that as well as the MTBF (Mean Time Before Failure) or, the average 
amount of time a drive will survive in normal use when left running, there is 
also a limit on the number of times a drive can be cycled up and down. (I think 
the SMART tools will tell you that, don't quote me.)

It sounds like a good idea to power down drives when you're not using them, but 
it is the warm-up / spin-down cycling of drives which can trigger the most 
failures. You are effectively temperature-stressing all the components. 
Sometimes it is better to find lower-power drives (-> more modern) and leave 
them going all the time.

Of course, if your system is only going to be in use a couple hours a day, then 
different rules may apply.

-- 

Mike Perkins