FWC with mutiple SSA loops

FWC with mutiple SSA loops

Post by g. doog » Tue, 15 Jan 2002 12:40:55



In a HACMP cluster I am currently using the FWC feature plus 128m dram
on single 6225 ssa adapters in each of my two nodes. The adapters currently
have only one loop which is located on the A-ports.  I am about to add a
second loop to these adapters on the B-ports.  Are there any issues with
FWC and multiple loops on the adapter?  Why do I remember reading something
about fast-write only having one "initiator"?      

Thanks for any help or suggestions!

 
 
 

FWC with mutiple SSA loops

Post by Scott L. Field » Tue, 15 Jan 2002 13:09:45


On older adapers you could not do RAID and multiple initiators. The newest
adapters (4N and 4P) don't have that limitation. However, they only allow TWO
initiators in a loop.

> In a HACMP cluster I am currently using the FWC feature plus 128m dram
> on single 6225 ssa adapters in each of my two nodes. The adapters currently
> have only one loop which is located on the A-ports.  I am about to add a
> second loop to these adapters on the B-ports.  Are there any issues with
> FWC and multiple loops on the adapter?  Why do I remember reading something
> about fast-write only having one "initiator"?

> Thanks for any help or suggestions!


 
 
 

1. SSA Hot Spares not in loop

Hi

Further to my previous post re SSA configs   (thanks for the replies)

I have 2 D40's with 32 18GB drives connected to 2 advanced SSA
adapters in a single system

I plan to create 4 loops with 8 disks each.   I am using RAID_10 on
three of the loops which means that four disks are striped, then these
four are mirrored onto the other four disks.  (The doco says that all
disks in the array must be on the same loop.)  The other 8 disks are
divided into three mirrored 18GB volumes and 2 18GB drives to be used
as hot spares.

I would like to have a hot spare available, however, would this mean I
would have to sacrifice 32GB per loop (ie 2 18GB disks)  OR  is it
possible to assign a hot spare to a RAID array even if the disk is on
a separate loop?

I do not have a spare system to test this on, and I only have an 8
hour window to cable in the new D40 (currently only one connected -
RAID5), then rebuild the arrays and restore 110+GB of data.  I want to
have my theory down pat before I turn off the power.

If hot spares can't be used across loops, I will have to re-think my
cabling plans to create just 2 loops, although this will mean
decreased bandwidth (I think).

Thanks

George

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