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MD1000 Split mode...cable both EMM's to same controller?
Can someone please help explain if it is possible (or advisable) to cable an MD1000 in Split mode, using both EMM's to connect to the same controller?
It seems there is conflicting information on the web about this and I'm a little confused whether I should be doing this for extra performance, or if it is not even supported.
Many thanks in advance:
Page 7 shows 2 controllers to one MD1000
http://support.dell.com/support/edocs/systems/md1000/en/supmatrx/May08update/md1000_SupportMatrix.pdf
Page 21 shows 1 controller (2 ports) to one MD1000
http://support.dell.com/support/edocs/systems/md1000/en/HOM/om_en.pdf
dining_philosop
60 Posts
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March 2nd, 2009 09:00
You should be able to do this. I am not sure you will get any additional performance unless your application requires very high data throughput. Most applications are drive spindle limited (IOPS). The other problem with doing this is that you will not be able to have any expansion when the enclosure is in split mode.
grm139
172 Posts
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March 2nd, 2009 11:00
What controller do you have?
If you have a PERC 5/E – MD1000 in split both EMMs can be cabled to both ports on the controller.
If you have a PERC 6/E – You can cable both EMMs to the controller in split or join mode. If MD1000 in join mode, the PERC 6/E FW will balance the traffic to disks. This is only supported on 6/E with the latest versions of the FW.
“SAS 5/E” is one of the tags in your ports. Dell does not support the MD1000 connected to a SAS 5/E.
shogg
5 Posts
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March 3rd, 2009 00:00
Opps...incorrect tagging, should have been PERC 5/E there as that is what I have.
I was just a little confused from the Dell manuals, which seem to say different things, and was trying to figure out if I want to look at splitting the enclosure for performance reasons, or if with the MD1000 and SAS....it really doesn't get you anything more.
Thanks for responses so far, anything else to further explain would be great.
grm139
172 Posts
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March 3rd, 2009 06:00
If you set an MD1000 with a SAS 5/E you will not have any HW RAID.
A split-MD1000-PERC5/E system has the potential of doubling the performance of a non-split system (two SAS cables vs. one) but, if there is any performance gain it will depend more on the IO load, the RAID configuration (RAID level, write cache, read cache, stripe . . . ) and the HDD performance. The split configuration will NOT hurt performance, it may only help.