[KLUG Hardware] re: "new" RAID level

[Mike Williams]

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>
>Date: Fri, 1 Aug 2003 16:16:06 -0400 (EDT)
>From: Adam Williams <awilliam@whitemice.org>
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>Yep, they should have called their other controllers RAID 0.9?
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>
At least it would have made them explain how broken their RAID 1 
implementation is.

>>>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. 
>>    
>>
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>You have to keep track of which requests have ben dispatched to which 
>drives.  Turns out to be much worst than "trivial"
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Still doesn't seem too bad.  Just two queues rather than one, since 
ATAPI doesn't support out of order execution.  You probably know more 
about it than I do, though.

>>>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.
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>ATAPI RAID is just silly anyway.  A stupid bus without any error 
>detection/correction;  and duping drives is going to help?  
>
Depends on the logic that they use to decide which drive is right if 
they disagree.  read-after-write would help, although the performance 
penalty would be pretty bad.  The FastTrack method of  only using one 
drive sucks, though.  When that one gets flaky (as has happened to me 
way too many times) there a 50% or better chance that the whole array 
fails.  I've had to rip out my RAID card and run the drive of the mobo 
connector about 3 times in the last year. 

>
>One should only use Western Digital drives in such a configuration, as 
>they die catastropically instead of degrading over time. 
>
So noted.  The gradual (OK, they fail too often to be called gradual, 
but it's not instant) failure of these
IBM's has been disastrous.