split backplane on PowerEdge 2650: win or no?

James Ralston qralston+ml.dell-poweredge at andrew.cmu.edu
Fri May 21 17:52:01 CDT 2004

On 2004-05-21 at 16:45:51-05 Jason_Mick at Dell.com wrote:

> You can either use the internal channels of the ROMB or an addin PCI
> RAID card to attach to a split backplane.  The ROMB will be cableless
> design

If I am reading this correctly, since I am using only the onboard SCSI
controllers (no onboard RAID; no other add-in SCSI and/or RAID cards),
simply installing the SCSI backplane daughter card will split the
backplane; no additional cables are required.

On 2004-05-21 at 16:58:33-05 Steve_Boley at Dell.com wrote:

> Can purchase daughtercard and 2nd scsi cable from spare parts
> and run split bplane with sware raid.
> J0661 is the cable
> 3D735 is the daughtercard
> With the daughter card inserted it will automatically split when
> you attach the 2nd cable to it.

Attach the second cable *where*?  According to figure 4-23 here:


...the SCSI backplane daughter card has no other connectors on it.
And the first bullet point of instruction #5 says "If a RAID
controller card is not installed, no cables are required to use either
the onboard SCSI controller or optional integrated RAID controller in
either a 1 x 5 or 2/3 split configuration."

> This will offload the commands to 2 of the drives to a separate
> controller so it will help but I'm not sure how much and would
> really show benefit under load.  The 7899s are on 64bit 66mhz bus of
> it's own so the prev statement of 33 was incorrect so it definitely
> would be to your advantage to split the controllers.

Thanks for the correction...


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