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August 29, 2008


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Massimo Re Ferre'

Good post Chad.

I have done a similar analysis (although probably less detailed) months ago with the only difference that I outlined the limitation of the product rather than the advantages (that I recognize). You know... I prefer to "challenge" my partners rather then please them too much ... otherwise they would sit still .... ;-)


Good stuff.... keep posting.

See you in Sin City @ VMworld.


P.S.: we will enable the DS8000... when it makes sense... ;-)

Chad Sakac

Thanks for the post Massimo, and your comments are other feedback I've heard from our largest customers that I didn't mention in the original post. Your post is good, but of course, all DR diagrams have looked like that for years (replace Shark with your pick of DMX/CX/Celerra and PPRC with your pick of SRDF/MirrorView/Replicator/Recoverpoint).

So, let's look at the downsides:

1) What about failover from the array perspective:
a) will it affect the entire config, or just the right things
b) what about where there are two teams and the storage team doesn't WANT to failover when the VMware team says "go?"

2) What about non VM applications?

on 1a) - No, SRM will only failover the LUNs it is handling, and where consistency technology is used, they failover in a consistency group/RDF group. So, no worries there.

on 1b) - this is actually a larger problem in my experience. SRM has no good mechanism to do this. What we've done for some of our larger customers for whom this is a problem (in smaller shops, since they are usually one team - this is actually a feature!) is use the test feature to build and test the DR plan, but then export it using the export feature. So, in otherwords, SRM doesn't automate failover for those customers, but actually automates the process of CREATING a runbook.

On 2) - SRM can (and again, we've done this for some of the customers through the beta and post-GA) act as the "coordinator" for multi-platform DR. For example, with one customer, they had a couple of Oracle 10g EE RAC databases on Solaris (Sparc, so not a VMware candidate) and some mainframe apps using SRDF. We showed how you could insert pauses, callouts, and script actions, but use SRM for overall coordination and storing the runbook. Clearly not something "out of the box", but multi-platform doesn't invalidate SRM, just means some extra help is needed.

For application sensitivity within VMs, you're right - an obvious thing to add, but you can do that now - every VM's start sequencing has a pre-poweron and post-poweron event where you can do whatever you want.

Re: enabling the DS8000 - I leave it up to IBM, of course, I hope you take your time, we're going like gangbuster with SRM at the high end on DMX and SRDF - I think we're the only enterprise array with a shipping SRA (in the Beta since January, and shipping since May) :-)

Craig Waters

Any chance you could provide a non-protected powerlink URL to the following document. Its frustrating when we can't/don't share the love: -

If you're a EMC CLARiiON MirrorView Customer, read this


Massimo Re Ferre'

I am not going to argue.... this is your blog and you get the last word! ;-)


Chad Sakac

Craig - I'm working to get all the docs re assigned to the "public category, and will link ASAP.

In the meantime - if you are an EMC cusotmer, or EMC Partner (including VMware), you can just login to http://powerlink.emc.com and search for H5583, and find it.

Craig Waters

Thanks for the reply Chad. I have tried to obtain this document through various channels:

1. I am an EMC Customer with acces to PowerLink, when I try and browse this URL I am informed that this information is restricted.

2. I contacted my EMC rep who stated this document was '...information that can be used to implement the SRM solution and is therefore customer billable...'

3. I contacted a colleague who works at EMC who after speaking with his boss echoed the above statement.

Hence my comment around information sharing and the lack of from EMC. I Look forward to your reply.

Many Thanks!

Chad Sakac

Craig - consider me on the case.

You will have a document in your inbox tomorrow. I will get the documents reclassified.

It's a stupid mistake, and one I'll fix.

Chad Sakac

Craig - you have the email with the doc. Again, my apologies it was hard to find, and I'm working to make these (and all) documents open to the public. Period.

In the meantime if you or anyone else is looking for something - don't hesitate to ask.


As always, thanks for your great insight.

I have been very interested in SRM since I saw the original product announcements. The only downside I see today is the cost of SRM. I am about to finalize a deal for a couple of CX4-120's. I was able to get the CX's approved but just have not been able to get the green light on the cost for SRM (the 1 license for each processor is killing me).

I will be giving it another shot towards the end of 2009 when I expect to have all of my quad socket dual core hosts replaced with dual socket quad (or more) core hosts. At that point in time I will buying half the licenses and may be able to do it. It would have been nice to fit it in with the initial CX-4 implementation next month but so goes life....

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