Re: Load source question (RE: Disk Upgrade)

[Sue Baker <smbaker@xxxxxxxxxxxx>]

Charles Wilt wrote on Tue, 18 Nov 2008 19:12:43 GMT:

> Your statement contradicts the statement made by Larry Bolhuis
> in June 2008, 
> http://archive.midrange.com/midrange-l/200806/msg00610.html 
>
> "There is one HUGE no-no when it comes to failed Load Source
> in a RAID environment: DO NOT stop the operating system until
> the drive is replaced. Unless is has been fixed with newer
> RAID cards, (Which I simply don't have the guts to try...) the
> system cannot IPL from a dead load source drive even though
> it's RAID protected. Thus it is extremely important to replace
> and rebuild that drive with all available alacrity!" 
>
> What models/RAID controllers support the IPL of the box with a
> failed, but RAIDed, load source?

I can't recall when this changed, or even that it has changed. 
The standard recommendation has always been to keep the system 
running and use concurrent maintenance to fix load source without 
IPLing. 

We like to try to break things with the latest hardware, 
firmware, and LIC.  I know one thing we did was pull the load 
source drive, shut down the system, and IPL before replacing the 
load source.  It worked.  

However, I would NEVER, EVER recommend doing this on a production 
machine.  I continue to recommend to customers to do everything 
humanly and technically possible to avoid an IPL when the load 
source drive is in a failed state.

> I remember my first model 400.  We had a mirrored pair for the
> load source and then a RAID set for the rest.

I like this combination too .... especially if you can get to IOA 
level mirroring.  However, the hardware support guys do not like 
this and consistently tell me to stop making this recommendation.   
Their argument is it is difficult to get set up.  And I agree 
it's not as easy as straight RAID protection, but I like the 
enhanced protection for load source especially if you can get to 
remote load source mirroring (IOA level or better mirrored 
protection).