[mythtv-users] Wishlist feature for adding a hard drive

[Andrew Davis]

Stephen Boddy wrote:
> On Thursday 05 October 2006 19:20, Robert Kulagowski wrote:
>   
>>> If you're using software RAID (md) then your writes will take a hit with
>>> RAID5.
>>>       
>> Isn't XOR one of the most optimized routines in a CPU?  I recall reading
>> a paper put out by Microsoft a few years ago where they benchmarked
>> software RAID versus hardware RAID, and that software RAID wasn't as bad
>> as everyone thought it should be precisely because a modern CPU can
>> execute XOR so quickly.
>>     
>
> While that may be true, the main point I'm getting at is that RAID5 won't 
> improve write speeds, because instead of a single write to a single disk, 
> there are at least two reads, a calculation (however short), followed by two 
> writes. (Obviously this is ignoring caches/buffers etc.)
>   
So you get a h/w RAID controller with good Linux driver support... such 
as the older ICP Vortex (not Intel owned) cards or an AMI MegaRAID (now 
LSI)... though there's also SATA versions available from Adaptec and 
Promise with Linux support.