[THIN] Re: DR project dumped on me

  • From: Russell Robertson <russell@xxxxxxxxxxxxxxxxxxx>
  • To: "'thin@xxxxxxxxxxxxx'" <thin@xxxxxxxxxxxxx>
  • Date: Tue, 8 Dec 2009 19:57:41 +0000

Hhmmm, HP have a product called Storage Mirroring  which is Double Take 
rebadged. This is far less complex compared to HP Continuous Access and would 
trust it far less than HP Continuous Access.

I would do lots of testing failing over and failing back if it's Storage 

From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of 
Sent: 08 December 2009 17:02
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: DR project dumped on me

His response:

"There will be Hardware replication over 100mb pipe.  There will also be 
application based replication via storage mirroring."


From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of 
Subject: [THIN] Re: DR project dumped on me

The implementation engineer still has not replied with what is being used for 
replication and the replication interval.


From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of 
Jeff Bolton
Subject: [THIN] Re: DR project dumped on me

Not usually, but it depends on how the replication was set up.  Essentially the 
SAN takes a PIT snapshot of the protected LUN and then replicates the delta's 
to the remote site.  The replication cycle is usually based on the defined RPO, 
so it could be anywhere between real-time to days.

From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of 
Joe Shonk
Subject: [THIN] Re: DR project dumped on me
If replication is done at the block level, is the VM quiesced before 
replication begins?  How often does replication occur?


From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of 
Jeff Bolton
Subject: [THIN] Re: DR project dumped on me

If they are using Site Recovery Manager for VMware, the replication to the DR 
site will be very easy.  SRM basically assists in creating a complete DR plan 
for virtual environments.  It works in conjunction with the SAN.  Basically the 
SAN is set up to replicate a particular LUN or set of LUNs, SRM then allows you 
to re-IP the virtual machines on the fly (if necessary) at the destination 
site.  The destination machines remain powered off, until a DR or test DR event 
is triggered within SRM, it then severs the replication and powers up the DR 

Because replication is done at the block level for the protected LUN(s), there 
is no need for any additional data replication between the two sites.

If they're not using SRM with VMware, it gets a little more complicated...

Hope this helps...



From: Webster <webster@xxxxxxxxxxxxxxx>
Subject: [THIN] DR project dumped on me

Two days before "go live" I have had a DR project dumped in my lap.  The 
original consultant is "no longer available".  I was not involved in the 
planning, project scope, design, recommendations or purchasing of anything 
involved in this project.  Customer has a main site and is implementing a DR 
site.  They are using ESX 3.5 on HP C class blades with a 30MB pipe between the 

For what I am responsible for, the main site consists of VMs for:

SQL 2005 for data store
License server
2 CSG3.1/WI4.6 in NLB
2 32-bit PS4.5 servers (Office 2007 and Acrobat Pro)
1 64-bit test XA5/FP2 on 2003 server

They want me to help them finish testing the 64-bit XA server and if approved, 
migrate all users to the 64-bit farm and rebuild the 32-bit servers as 64-bit 
servers.  Then they want all of this duplicated in the DR site.

I am not familiar with ESX and what it uses to move VMs between host servers.  
All hardware is identical between the two sites.

They will be using some VMware/EMC utility to replicate VMs and data between 
the two sites.

My question, if ESX has a utility that replicates the VMs between the two sites 
and the DR site VMs will NEVER be "on" when the main site is functional, what 
else needs to be done.  If the VMs in the DR site will have the exact same IP 
addresses, computer names and configurations as the VMs in the main site, all 
that should need to be done in a DR scenario is to point the users to the new 
public IP of the CSG at the DR site?  Correct?

Does the SQL data store need to have the Publisher/Subscriber replication 
setup?  Wouldn't think so in this case.

What other info do you need to help me wrap my head around this since I am 
supposed to start on this Thursday (and I will be at Ctx HQ all next week)?



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