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High Availability Unity system

admin_2
Level 3
Level 3

I am looking for some info on building high availability Unity systems. We have a customer who wants 99.99% availability from the system.<br><br>I am new to Unity, and would like to better understand the resilience/redundancy options. Is there a whitepaper on the subject I could read?<br><br>Is runing Unity on an NT cluster an option?<br><br>Apologies if this has been asked before, I did search the forum before posting but didn't find anything much on this topic. Also is there an FAQ available and if so from where?<br><br>Many Thanks<br><br>Tim Banks<br><br>Solution Architect<br>MCSE Unity SE<br>Compaq Global Services

29 Replies 29

Not applicable

Hey Tim.

For Unity 2.4.6 the only high availability option is the “simple failover” capability, which is pretty limited. There is a section in the 2.4.6 readme file (found under the \documentation directory on CD #1) covering the details of how to configure two Unity servers such that one is the backup to the other. There’s a number of limitations to this configuration, for instance MWIs and notifications will not function while the primary is off line and the like. Must of the work here comes from setting up your switch to properly route calls when the primary Unity server is off line.

If you don’t have a set of 2.4.6 CDs at your disposal, email me and I’ll zip them up and send them your way to take a look.

No, running Unity on an NT cluster is not an option. We do have a couple of sites that have Unity (with Exchange of course) on it’s own box and we are talking to an Exchange cluster where all the subscribers are homed. Frankly this doesn’t work all that well since Microsoft has never figured out how to get the client connectivity to seamlessly handle an Exchange server going off line (i.e. if you have Outlook attached to that server when it goes down you have to stop Outlook and restart it before it’ll reconnect to another server in the cluster). It’s not exactly smooth and since Unity uses the same client libraries to connect to Exchange, we get hit with the same problem (i.e. Unity would have to be restarted in some scenarios). Same deal with all the “mirroring” products from 3rd parties… you can get your backup on line fairly quickly but it’s not “hot failover” by any stretch of the imagination. The quest for a seamless hot failover solution based on Windows clustering is still a bit off into the future I’m afraid.


Jeff Lindborg
Unity Product Architect/Answer Monkey
Cisco Systems
lindborg@cisco.com
http://www.AnswerMonkey.net (new page for Unity support tools and scripts)

For the simple failover, what kind of programming has to be done in the switch? We Just have a VG200 Gateway, a Call Manager & a Unity.

Can the backup Unity box be of a completely different hardware breed?

For simple failover in Unity 2.4.6 , you just need more phone lines and have to setup the response ring rate on the Unity's to be different.
You can have the secondary server on a different hardware. Just make sure that it is big enough to handle the requests that your primary handles and it is in the HCL for Unity.

Anil Verma
Cisco Systems
anilve@cisco.com

Then there is no special programming to be done in some "switch" (maybe switch meant: Cisco router or Call Manager or catalyst switch)?

From the forum I read these exact words from Jeff L. about how to set up a simple failover:

"...When the primary goes off line calls will get picked up by this 2nd server. The switch, however, is responsible for being smart enough to route calls to the 2nd box when the primary fails to answer and the mechanism for doing this varies depending on what kind of switch you’re using (this is the tricky part)..."
"Most of the work here comes from setting up your switch to properly route calls when the primary Unity server is off line."

Please let me know about this switch programming issue.

Thanks,

Kimberly


What Jeff is saying is absolutely right.
You have to setup the switch so that it knows to route the call over to the secondary Unity when the primary cannot answer. There are more than one ways to go around setting this up in the Call Manager. This forum deals with issues related to Unity. For specific Call Manager configurations and solutions, you will need to go to their forum. Check out this link -
http://avforums.isomedia.com/cgi-bin/showthreaded.pl?Cat=&Board=ipswitch&Number=3085&page=0&view=collapsed&sb=5

Anil Verma
Cisco Systems
anilve@cisco.com

Ok. But when you use the term "switch", what are you referring to?

"Switch" meaning Call Manager?
"Switch" meaning router or catalyst switch or gateway?

Switch meaning the Phone Switch, which in this case will be the Call Manager.

Anil Verma
Cisco Systems
anilve@cisco.com

Thank you for defining what the word "switch" means referring to the Unity simple failover procedure.

So all that is needed should be: programming the Call Manager's uOne ports (Voice ports) & setting the backup Unity server to answer on maybe 3 more rings than the primary Unity server.

Can Unity 3.0 work with simple failover since hot failover is not supposed to be out till Unity 3.1?

Thanks for the help.

Thanks,

Kimberly

No Unity 3.0 does not support any failover. It is to be released with Unity 3.1.
If you have a customer who already has failover in Unity 2.4.6, and cannot wait till Unity 3.1, please contact your Cisco sales personnel. They might be able to offer some solutions, but they will not be pretty.
My advise, wait for Unity 3.1, that is the best option.

Anil Verma
Cisco Systems
anilve@cisco.com

When is 3.1 supposed to come out?

I am asking all of this because we have a very big customer who is interested in IP telephony but they want everything to have an immediate hot failover which is not the case for Unity right now. I would like to tell them that Unity at least offeres simple failover but a gap, not even offering simple failover from 2.4.6 to 3.1 is not acceptable for them. They are a company that does all their business over the phone.

Once you told me there was no simple failover capabilites with Unity 3.0x, I thought maybe we could set them up with Unity 2.4.6 for now & then upgrade to Unity 3.1 when it comes out. But I don't want them to have to buy 2 seperate software licenses for two machines so close together & maybe involving rebuilding the servers from scratch when Unity 3.1 comes out.

There are no confirmed dates on the Unity 3.1 release.
This forum cannot really resolve sales issues. You really need to get into touch with the friendly neighbourhood Cisco Sales personnel. They can really help you out on your options.


Anil Verma
Cisco Systems
anilve@cisco.com

Will the forum announce when there is a date for Unity 3.1?

Our company is a Cisco gold parnter. We buy direct from Cisco.

Not applicable

yes... we always anounce releases and patches out here on the forum when they become available.


Jeff Lindborg
Unity Product Architect/Answer Monkey
Cisco Systems
lindborg@cisco.com
http://www.AnswerMonkey.net (new page for Unity support tools and scripts)

Jeff,

Is there anyone at Cisco who can give us even a hint at what quarter it might come out?

This big customer is looking to purchase a hot failover redundant vmail system for February installation in a new office.

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