[mythtv-users] Fastest RAID for HD?

[Brian Wood]

Emery Guevremont wrote:
> David Brodbeck wrote:
>> On Feb 14, 2008, at 7:25 AM, John Drescher wrote:
>>   
>>> As  I said before raid5/raid6 are bad when they thrash.
>>>     
>>
>> Definitely true.  The extent of this can be pretty shocking.  I've  
>> seen hardware RAID 5 arrays slow from megabytes per second when  
>> writing large files to a few dozen kilobytes per second when writing a  
>> bunch of small ones.  I don't know if this would be a problem for  
>> Myth, though; Myth files tend to be large.
>>
>>   
>  From my experience, with Linux, software raid is a lot better than 
> hardware raid.

That's a pretty broad statement.

I would agree that under some circumstances (fast CPU, running on a good 
UPS) Linux software RAID can be as good as some hardware RAID setups. It 
also eliminates some of the problems with H/W RAID, like some 
controllers are very picky about what drives they will work with, and 
the need to get an exact replacement if a controller fails.

But there are circumstances where H/W RAID is a better solution. The 
ability to have separate (battery powered) RAM for cache and the ability 
for your BIOS to see the array as a single drive are examples, though I 
admit that these are not usual situations for Linux Myth systems.

beww