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 Post subject: Remote Copy SLD configuration
PostPosted: Wed Jul 17, 2019 2:11 am 

Joined: Mon Aug 13, 2012 9:00 am
Posts: 22
hiya

In an Synchronous long distance configuration is it possible to convert to a 1:1 Asynchronous periodic configuration using the just the two secondary sites?
I believe that if Site1 is the primary with a synchronous RC configuration to Site 2 and Asynch periodic to site 3 and Site 1 fails, the RCG will failover to one of the other sites and start replicating over the 'backup link' between site 2 and site 3.
I want to retire the Site 1 array and so this is the scenario I want to achieve, but I don't want the array to be permanently in 'secondary reverse' setting and need this array to be the new primary.

thanks in advance


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 Post subject: Re: Remote Copy SLD configuration
PostPosted: Wed Jul 17, 2019 4:34 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 920
Location: Europe
Not getting the full picture here, but here goes.

Unless you have a quorum witness and peer persistence (or use external tools like CLX), nothing will happen if site 1 fails. There is no automatic failover as site 2 and 3 doesn't know if site 1 is down or just replication is stopped.

I don't think you should see secondary-rev if you've done a proper failover from site 1 to site 2. If you have a situation where something is -rev you would have to use the "setrcopygroup -reverse -natural...." to get it back to normal "primary" and "secondary". Watch your step here as you could in worst case overwrite your good volume with the older replicated version on the other site.

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 Post subject: Re: Remote Copy SLD configuration
PostPosted: Wed Jul 17, 2019 6:09 am 

Joined: Mon Aug 13, 2012 9:00 am
Posts: 22
Hi
Thanks for your help - and I'll try to give you the full picture as perhaps you can suggest options.

Essentially we have 3 x 3PARs in three different datacentres (DC1, DC2 and DC3). DC1 and DC2 are old 8200's which we have had for many years and these two are in a 1:1 remote copy relationship using a 4 node MS cluster and CLX. A new 8400 (four node) 3PAR has recently been installed at DC3 and we need to migrate all the data from DC1 to DC3 so we can decommission the DC1 3PAR. Much of it is migrated using VMware storage vMotion and the less critical servers have been migrated using backup\restore etc. The last remaining data is the vv's that are in the RCG for the MS cluster using CLX. The current RC relation between DC1 and DC2 needs to be changed to exist between DC3 and DC2 - but I want to do this without having to resync any RCGs as there is about 40TB of data and the link between DC2 and DC3 is quite contended.
So my thinking was along the lines of creating an SLD to include the DC3 3PAR to get this in synch (with DC1 as the primary) and then to failover the CLX to DC2. I was then hoping to be able to get this to replicate to DC3 and DC1 whilst in the SLD before eventually removing DC1 from the SLD to just leave DC2 and DC3 in a 1:1 RC relationship (the CLX cluster nodes at DC1 would be relocated to DC3 also.

I hope that adds a little more clarity to my question.

thanks again for your input


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 Post subject: Re: Remote Copy SLD configuration
PostPosted: Wed Jul 17, 2019 6:38 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 920
Location: Europe
What about the MS cluster servers in DC1? Do they access 3PAR in DC3 or is there a new set of servers in DC3 as well?

If the servers can access DC3 and you have FC connectivity between DC1 and DC3 I would look at Peer Motion. If you can use Peer Motion, then I think your entire SLD strategy has been going down a more difficult road... With CLX it will always do a lot of stuff whenever you failover the cluster.

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 Post subject: Re: Remote Copy SLD configuration
PostPosted: Wed Jul 17, 2019 6:44 am 

Joined: Mon Aug 13, 2012 9:00 am
Posts: 22
DC1 to DC3 has 10Gbe but no FC capability so I can do synchronous RCIP but not Peer motion unfortunately.
There are no cluster nodes in DC3 - that's not to say a couple couldn't be added - but a CLX failover would only work if DC2 became the primary. With DC2 as the primary and DC3 in synch, the cluster nodes in DC1 would be physically moved to DC3. DC1 could then be removed from the SLD config leaving DC2 and DC3 in a 1:1 configuration.


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 Post subject: Re: Remote Copy SLD configuration
PostPosted: Wed Jul 17, 2019 6:44 am 

Joined: Mon Aug 13, 2012 9:00 am
Posts: 22
DC1 to DC3 has 10Gbe but no FC capability so I can do synchronous RCIP but not Peer motion unfortunately.
There are no cluster nodes in DC3 - that's not to say a couple couldn't be added - but a CLX failover would only work if DC2 became the primary. With DC2 as the primary and DC3 in synch, the cluster nodes in DC1 would be physically moved to DC3. DC1 could then be removed from the SLD config leaving DC2 and DC3 in a 1:1 configuration.


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