[mythtv-users] Raid configurations

Terrence Martin tmartin at physics.ucsd.edu
Fri Aug 13 22:43:36 EDT 2004

Stephen Tait wrote:

> RAID6 is pretty CPU-intensive (more so than RAID5 IIRC, but I could be 
> wrong), as there's lots of parities to calculate 
> http://www.acnc.com/04_01_06.html
> Personally, I'd go RAID10 (striped mirrors, and can sustain the loss 
> of up to two drives in a four drive setup) which would give you 500GB 
> worth of stripe, but if you need the space, personally I'd stick with 
> RAID5 (possibly sacrificing one of the discs as a hot spare) which 
> would give you ~750GB (can't remember the exact formula).
> My usual advice for complex RAID setups is to splash out on a 3ware :) 
> The only problem with this at the moment is that support for the new 
> 9000 series isn't in any mainstream kernels yet. I'm personally going 
> to be throwing my backend onto a RAID10 over four 250GB (or more) drives.

First I did not realize they were asking about RAID6. I assumed RAID5, 
that is what I run. Anyway....

Don't be so quick to assume 3ware is going to deliver you into some 
hardware raid performance nirvana. 3ware cards can be irritatingly 
difficult to get good performance out on Linux, even with their 
recommended tweaks. I know I have a lot of them.

For the money the TX4 plus linux software raid makes a good combination 
and should provide all of the performance needed.


> At 16:52 13/08/2004 -0500, you wrote:
>> Anyone see any performance problems if I used four WD2500JD drives hung
>> off a Promise SATA150 TX4 in software RAID6 for video storage? Of
>> course, XFS on top of that.
>> I just really don't want a single failure on a huge RAID0 video volume
>> to destroy ALL my video.
>> I figure that'd satisfy my storage cravings for a while, and be
>> virtually free of worry for me, barring some form of corruption.
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