Re: Redundancy: Multiple 890s and multiple Shark F20

Dennis,
Long time no keyboard!  :-)  There are some pretty stringent requirements for 
mirroring on the iSeries as I recall.  Mirrored pairs is what falls out of 
feeble mind at the moment.
Most folks have chosen a HA solution to do this.  There are many providers in 
the iSeries arena.  The ones that come to mind is Lakeview Technologies and 
Vision Solutions.
<hth>
Regards,
Mike Shaw


-------------- Original message -------------- 

> Hello, Midrangers: 
> 
> I am reviewing an iSeries implementation at a bank in South America. In 
> this process, I have found an interesting anomaly I had never heard of.... 
> and I hope that one of you good people can clarify for me. 
> 
> Overview: Two 890 systems, each connected to its own Shark F20 Storage 
> device. (In other words, 2 890's and 2 F20's). Each of these systems is 
> configured with BUS level mirroring. Most of the redundancy issues seem to 
> have been addressed, except one. It made sense (to me ) to recommend that 
> the iSeries systems have connections to BOTH F20 (with one copy of the 
> mirror on each F20). So we'd have this sort of configuration (sorry for the 
> poor graphics..... 
> |---------------| 
> | | 
> | 890 | 
> | | 
> | | 
> |---------------| 
> | \ 
> | \ 
> | -------\ 
> | \ 
> |---------------| |---------------| 
> | SysA Mirror 1 | | SysA Mirror 2 | 
> | | | | 
> | | | F20 | 
> | F20 | | | 
> | | | | 
> | SysB Mirror 2 | | SysB Mirror 1 | 
> |---------------| |---------------| 
> \ | 
> \ | 
> \----------\ | 
> \ | 
> |---------------| 
> | | 
> | 890 | 
> | | 
> | | 
> |---------------| 
> 
> When I presented this concept, it was shot down. The Client indicated that 
> they 
> had been through this scenario with IBM; they were told that in this 
> configuration, if one of the F20 Shark units fails, it will bring both 
> iSeries 
> systems down. 
> 
> This surprises me greatly... which is why I'm here. Can any of you confirm or 
> deny that: 
> If a Shark F20 fails while connected to an iSeries, the iSeries will also 
> fail 
> (even if the redundant Shark is still running) 
> Above being true, an EMC solution or other storage solution cannot resolve 
> this point 
> 
> It seems unthinkable in this age that such an obvious single point of failure 
> cannot be resolved. I'd love to hear your thoughts. 
> 
> Regards, 
> -- 
> Dennis Lovelady 
> -- 
> "Television is a device that permits people who haven't anything to do to 
> watch people who can't do anything." 
> - Fred Allen 
> 
> 
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