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SAP on HARWARE Cluster - possible and recommended ??

Former Member
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Hello Gurus,

We are planning to install SAP on MSCS Windows Cluster, but then hardware vendor came up with a proposal wherein they gave a demo to us for a server which is Fault Tolareance (FT) and is based on Hardware clustering.

According to him its a high availability server which has better response and availability compared to MSCS server.

I need to know now can SP be installed on these FT servers?? If yes will it be a high availability?? and will SAP support this installation ??

To me it seems a very practical and good approach even for future aspects, but I little considerate as haven't heard of any production environment setup on hardware cluster.

Any replies and help or discussions are much appreciated !!!

Cheers !!

Shobhit Garg

Accepted Solutions (1)

Accepted Solutions (1)

Former Member
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SAP isn't installed on a hardware, but on an operating system.

Even on that hardware cluster you will still need some kind of operating system.

So you have to ask two questions:

1) Will the hardware cluster be compatible with your chosen operating system?

2) Will your operating system be compatible with your SAP product?

For the second question, have a look at http://service.sap.com/pam

Besides that, I would ask the hardware vendor for references. Are there any companies running SAP on this hardware?

hope this helps

PS:

In case your hardware vendor is talking about Virtualization, look at

SAP Note 1492000 - General Support Statement for Virtual Environments

Edited by: Joe Bo on Jan 18, 2012 3:08 PM

Former Member
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Hi Joe,

I already had the presentation from hardware vendor and they are saying that they will take care of clustering part.

OS installed would be Windows 2008 R2 itself by Hardware team.

What I am worried about is as the server will be hardware clustered so that means auto sync of data will occur inside the server between the two clustered machines. Now suppose SAP app fails then I don't think other node will start SAP on it....because from front there is only IP assigned to server although it contains 2 machine clustered together inside.

Do let me know if you get my point, and I am really happy to discuss about it because this may be the future for SAP installations.

Also the server I am talking about is FT ( Fault Tolerance) , you may Google about to get its details too.

And unfortunately vendor said there are no productive instances as of yet running on this server, but they say they have SAP certification.

Thanks for deep discussion mate. Would like to have more inputs on this forum please.

Cheers !!

Shobhit Garg

Former Member
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Hi Shobit,

1) What I am worried about is as the server will be hardware clustered so that means auto sync of data will occur inside the server between the two clustered machines.

Most of the Implementations would be based on Hardware cluster and If one of Hardware fails, Application switches to standby Hardware or second Node.

Refer to the link http://help.sap.com/saphelp_nw04/helpdata/en/04/285ea6a87f11d194a400a0c930df15/content.htm

2). Now suppose SAP app fails then I don't think other node will start SAP on it....because from front there is only IP assigned to server although it contains 2 machine clustered together inside.

The Second Node will not START SAP. You need to go thru some of the MSCS document.

The Message Server (ASCS- ABAP or SCS Java) is Installed on Node which also has CI or DB or Both running. The Second Node will be installed with Additional Dialog Instance which might also can run DB.

Typically, Mesage server + CI run on one node, Additional DI + DB will run on second Node.

When first node which has Msg + CI fails....the MSG server fails over to second node which has DI and DB and second node acts as CI.

if Second Node fails, DB will failOver to First Node.

In Both cases Enqueue Server and Replicated Enqeue server keeps the locks, so no worry about losing the transactions.

I haven't worked on Fault Tolerence, you and your business is the best Judge to decide on that and I have read a document on FT and looks really good to me.

Hope above helps you

Regards,

Arjun

Former Member
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Hello Shobhit,

that seems to be an interesting subject. I read a bit about it, but I don't dare to say that I fully understand it. I will try to learn more about it.

Thanks for bringing it to my attention!

If I correctly understood, there will be no clustering software like MSCS Windows Cluster, and no two nodes ?

From my limited understanding I don't think that you have to be afraid of an SAP app failing and not coming up again.

I would rather compare this cluster with a single multiprocessor machine, having better fault recovery features though (hopefully).

If let's say one processor fails, then the process currently running on this will crash, and it may or may not be restarted. This process may be an SAP work process, resulting in a short dump. But it should not be a whole SAP instance crashing. The instance should be distributed all over the hardware cluster anyway. Or what does the vendor say here?

And as there are no productive SAP systems yet on this server, I am afraid you won't get much feedback here.

But it's great you started discussion!

regards

Former Member
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Hi Joe,

Yes you are right, there will be no software MSCS clustering and no two nodes either.

As I said, I am not worried about hardware failure, because in that case hardware vendor told me it can use clustered benefits.

But the problem is what if SAP application fails ??, in MSCS we still have another node where SAP Cluster services will fail over and there would be no downtime.

Now since this will be central system installation and not MSCS clusterbased so I still want to know if SAP app failure would be supported by this type of cluster or not.

Thanks for showing great interest in this topic !!

Cheers !!

Shobhit Garg

Former Member
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Hello Shobbit,

Thanks form confirming my understandings.

I am still not sure what kind of SAP application failure you are afraid of?

In my understanding the various work processes of let's say an ABAP instance will be distributed all over the hardware cluster. If some of them crash, they will be restarted, like in a usual SAP instance.

On the other hand, there may always be crashes that will require your intervention. For example sometimes (not very often, but it happens sometimes) a new SAP kernel won't be stable, and there will be no other choice than reverting to the old one.

For crashes of a whole SAP instance (how likely or unlikely it may be), it should be possible to implement some kind of watchdog functionality. That's the way other clusters like Oracle RAC or MSCS deal with failures.

For example we are using Oracle RAC together with sapctl. This way a failed instance will be restarted, on one of the remaining nodes. (Well, actually sapctl is far from mature. We are hoping for the next release!)

I dare say something similar should be possible in your new environment as well. But I don't know whether it is there already, or, in other words, whether you can make use of existing tools like mentioned sapctl.

Then there is the problem of a failing enqueue server. If there is a sync of memory, you shouldn't get much problems. But I would like to learn whether an enqueue replication server will be required, like in a conventional cluster.

And out of interest, you were talking about SAP, but which database will you use?

regards

Answers (1)

Answers (1)

former_member184628
Participant
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Hi Shobhit,

I have seen hardware cluster in SAP enviornment on linux platform. It is as stable as cluster.

The landscape has CI and DB on hardware cluster. The cluster was done by one of the worlds best HW company. But these are very expensive as compared to MSCS Windows Cluster, as they need additional hardware..

Best Regards,

Sharib