[mythtv-users] How is this pricing possible?

[Alex Butcher]

On Thu, 3 Mar 2011, John Drescher wrote:

>> That's pretty good; my experience with parity RAID has been with hardware
>> RAID controllers where the write performance has been truly miserable (a few
>> 10s of MB/s). Yet another example of how the embedded processors used in
>> most hardware RAID controllers have fallen behind software RAID running on
>> the main CPU (providing you have a core to spare).
>>
> The main problem there is if you do not have the battery backup unit
> most HW controllers do not use a stripe cache. And thus every write
> that is less than 1 stripe will require a read, update then a write of
> the stripe. This will totally kill performance.

Hmm. Might have been. I think I first noticed it on a system I didn't spec
and it's entirely possible whoever did was stupidly skinflint.

I've always adopted the thinking that if it's worth using hardware RAID
controllers, it's worth buying their respective battery backup unit. I seem
to recall RAID5 performance was still a bit sucky, but perhaps it wasn't
quite as bad as that original system I looked at.

> John

Best Regards,
Alex