[mythtv-users] INFO: RAID comparison for MythTV

[David George]

MagicITX wrote:

<snippage>

>While the number of drives in a RAID 5 array is theoretically
>unlimited, some recommend no more than 14 drives.  The problem is RAID
>5 is hosed if two drives fail.  The more drives you have the more
>statistically likely you are to suffer a two drive failure.
>  
>
While still not perfect, this is why you would want a hot-standby drive 
in a RAID 5 setup.  You will only be running in degraded mode for as 
long as it takes the system to rebuild the array on the hot-standby, not 
for as long as it takes for one to a) buy and install a new drive, or b) 
install a spare that was sitting on a shelf.  Granted this still doesn't 
help if you lose two drives at the same time or lose a second drive 
while the system is rebuilding the array.  Also RAID 10 can also lose 
all data in the entire array if two drives in the *same mirror* fail.  
Granted I am just picking nits here :-) :-)  RAID 5 is more prone to the 
two drive failure problem as it can be *any* two drives in the array.

Good article though.  For me it is just TV.  My video storage is on RAID 
0.  If a drive fails and I lose all my shows, I'll be sad, but life goes 
on ;-)

In case anyone is interested:
http://en.wikipedia.org/wiki/Redundant_array_of_independent_disks

-- 
David

HDTV frontend I'm working on (picture of back, mythmon source)
  http://mythhd.info