[KLUG Hardware] "new" RAID level

[Adam Williams]

>I give this about 3 responses before it gets forced into advocacy, but 
>here goes my rant anyway.  A couple of new high-end motherboards are 
>using a Highpoint RAID chip that claims to offer something called RAID 
>1.5.  Now they don't pretend that this is a combination of  RAID 1 and 
>5, but a sort of  "RAID 1 and a half".  What it actually is, however, is 
>just RAID 1 done right.  Most one-chip IDE RAID cards (as somebody on 
>list here has explained to me) do all of their RAID calculations in 
>software.  What's worse is that if you use RAID 1 (mirroring) with most 
>of them, the drives are not equal in the eyes of the controller.  It 
>only ever reads from one drive, so there's no performance advantage over 
>a single drive on reads, and a disadvantage on rights.  All this RAID 
>1.5 does is alternate read requests between the two drives, which any 
>real RAID 1 implementation should be doing anyway.  

Yep, they should have called their other controllers RAID 0.9?

>There's no reason 
>not to when the drive contents are identical and it seems to me to be a 
>trivial amount of extra code. 

You have to keep track of which requests have ben dispatched to which 
drives.  Turns out to be much worst than "trivial"

>The part that bothers me is that in the IDE world, broken RAID 1 has 
>become such a standard that they have to invent another name for it when 
>somebody finally does it right.

ATAPI RAID is just silly anyway.  A stupid bus without any error 
detection/correction;  and duping drives is going to help?  

One should only use Western Digital drives in such a configuration, as 
they die catastropically instead of degrading over time. :)