[mythtv-users] Fastest RAID for HD?

[Emery Guevremont]

Brian Wood wrote:
> 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.
>
I know I was broad. I just haven't had good experience with Raid 
hardware. When things start breaking down (not a hard drive failure, but 
a motherboard or controller failure for instance), rebuilding a disk 
with software raid in linux is a lot easier then with hardware raid. 
Switching around hard drives in a raid setup from one server to another 
server is a lot easier then with hardware raid. Plus there's the fact 
that hardware raid runs it's own proprietary formats for writting to disk.

Bah, it doesn't matter. But for the cost, it's pretty impressive what 
you can accomplish with software raid in linux.
> beww