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Separate replication interfaces / jumbo frames...
Hi,
We have a pair of Compellent installs, which will be replicating from one to the other. All of the ESX hosts we are using will be running jumbo frames across 10GbE iSCSI, and there will be a 100Mb link between the sites for replication - this link is uplinked from the iSCSI switch stack at each location. At the moment we are using an MTU of 1500 on the controllers, obviously I wish to set this to 9000 to increase performance however will this affect the replication? Will I need to set an MTU of 9000 for the replication links due to them being uplinked off the same switch? Alternatively we have a pair of 1GbE Qlogic adapters in each controller, would it make more sense to dedicate those to the replication and remove the iSCSI stack uplinks, that way I can segregate the links and leave the replication links with standard frames and configure jumbo frames on the switch stack?
Help please....
JD
hellraiseruk
38 Posts
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August 29th, 2012 08:00
Would this work if I'm running with virtual ports? Or would I need the replication links to be in a different subnet?
hallidayr
48 Posts
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August 29th, 2012 08:00
Yes, if you try to perform replication off the 10 GbE cards it should try to use 9000 byte frames. If you can get the 1 GbE HBAs in there that would be the best course of action. Additionally you won't run into issues with replication causing imbalances on the actual SAN links.
hallidayr
48 Posts
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August 29th, 2012 09:00
Different physical interface, MTU is tied directly to the NIC
hellraiseruk
38 Posts
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August 30th, 2012 04:00
OK, so how do I go about configuring it? Do I need to configure the replication ports as front end ports in the appropriate iSCSI fault domains so I can use the control IP for replicating between the two systems?
Thanks for your help so far :)
Justin
hallidayr
48 Posts
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August 30th, 2012 06:00
We haven't set up replication yet (lack of license) but my book from training indicates that it's a sort of wizard in Enterprise Manager. It shows steps of connecting via management IP and then selecting the iSCSI ports to use individually. But I'm not sure quite how these have to be configured... if someone else doesn't pop in that'd be a good question for Copilot. You should take a look at the documentation at https://kc.compellent.com/ under Enterprise Manager
Cheers
hellraiseruk
38 Posts
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August 30th, 2012 07:00
Yeah, I had a look at that but it seemed incredibly vague - unfortunately the only IPs the wizard lists are the control IPs, not the individual IPs of the links I want to use for replication. Common sense dictates I would add these as front end ports, then the control IP would potentially be available on them, but I don't know...
Thanks all the same :)
JD
PeterKirk
5 Posts
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November 19th, 2012 23:00
Hi
We did this exact setup and its working fine. iSCSI traffic over 9000MTU on 10GB and replication over 1500MTU over a 1GB link
All that you have to do is setup a new subnet and create new fault domains
Oh and we have virtual ports configured.
On a last note, on the DR side we do not have a separate subnet for replication, it goes over the iSCSI network as we decided not to use jumbo frames there
Hope this helps :)