Warm Standby

[former_member231251]

Hi All,

I am very new to replication, please help me accomplish one of the tasks at hand in my new job.

The details are as follows

Primary Dataserver - ASE1

Primary Database - pubs1

Standby Dataserver - ASE2

Standby Databasae - pubs1

Currently we have warm standby between ASE1 and ASE2

Replication Server REP1 has ASE_RS and ASE_RSSD

Now the task is to Implement a warmstandby between ASE2 and ASE3 where ASE3 will be used for reporting purposes only.

In this solution, ASE2 will be primary for ASE3 (Standby)

Questions:

1 - Can it be done. If Yes, please provide me detailed steps to do it

2 -  Do we need to install a replication server at ASE2 and also at ASE3

3 - Does the new warmstandby have any implications on ASE2 dataserver and database

4 - Is there any other way to accomplish the task (other than warm standby)

5 - There are multiple databases with data around 10-15 GB that are being replicated (Please consider the size of db's for a good solution)

Please provide step by step instructions to accomplish this task. Your efforts will be appreciated

If there are any SAP notes, please give me details

Thanks & Best Regards

AB

[former_member231251]

Dear Mark,

ASE Versions are 15.7 sp136

Replication server 15.7

The first solution which you gave me is what I am looking for i.e

ASE1.pubs1 <---WS--> ASE2.pubs1 <--WS--> ASE3.pubs1

ASE3 would be used only for reporting purposes. Hence there wont be any switch taking place.

pubs1 was just one database I gave for clarity, there are 8 more databases whose size is on an average 8GB.

Currently all these databases have a warm standby setup between ASE1 and ASE2 and switchin is on for a failover.

What we want to do is to have a simple warm standby between ASE2 to ASE3 for all the databases.

The requirement is to have a copy of ASE2 into ASE3 (all databases) for reporting purposes. Currently we are doing a netbackup dump and load from ASE2 to ASE3. The client wants to have a warm standby or perhaps a better solution from you Mark.

Let me know if you have any questions for me to answer.

Thanks & Best Regards

AB

[Mark_A_Parsons]

To make sure the reporting db (ASE3) is always downstream from your WS pair ... regardless of which is the primary (ASE1 vs ASE2), you'd want to setup a MSA off of the ASE1/ASE2 logical db handle.

Let's say you have transactions flowing in the following direction in your WS setup?

ASE1.pubs1  -->  (WS) LS1.pubs1  -->  ASE2.pubs1

Where 'LS1.pubs1' is the name of your WS/logical connection.

After a 'switch active' your flow of transactions looks like:

ASE1.pubs1  <--  (WS) LS1.pubs1  <--  ASE2.pubs1

----------------------

I'm assuming that under both of the above scenarios you always want a copy of all transactions to also flow into the reporting db (ASE3).  If this is the case, then you'll want to set up MSA replication from the LS1 logical connection to ASE3.  So the above scenarios would become:

ASE1.pubs1  -->  (WS) LS1.pubs1  -->  ASE2.pubs1

                       |

                       |-- (MSA) -->  ASE3.pubs1

After a 'switch active' your flow of transactions looks like:

ASE1.pubs1  <--  (WS) LS1.pubs1  <--  ASE2.pubs1

                       |

                       |-- (MSA) -->  ASE3.pubs1

If this represents what you want, they you would want to setup MSA like follows:

- create a MSA/database repdef with LS1.pubs1 as the PDB

- create a MSA/database subscription with ASE3.pubs1 as the RDB

----------------------

I would highly recommend that you routinely test the 'switch active' command (at least in a test env) so that you understand how it works, and to get used to troubleshooting it if there are any hiccups/issues during the switch.

----------------------

While there's nothing technically wrong with using WS, over the years I've had intermittent issues with the 'switch active' command failing part through its process, which in turn becomes a major pain in the arse to fix as there are a lot of steps that 'switch active' performs under the covers (and inevitably the problems occur in a PROD environment when I have little time to address/fix the issue ... can you say high stress? 🙂

Soooo, I would also recommend you give some thought to replacing the WS configuration with a pair of MSA repdef/subs.

Luc Van der Veurst had a great write-up on why/how he converted all of his WS configs to MSA.  You can see his write-up in this thread:   (scroll down about half way to find Luc's post)

[former_member231251]

Mark,

Thanks for gem of a solution. This really simplifies my requirement. Although I need some inputs from you, as I have told you I am new to Rep Server Domain.

1 - Do I create one DB Rep Def for each database and one subscription for each DB Rep Def. We have 8 databases to replicate in ASE3.

2 - What steps should I perform in ASE3 like do we install Rep Server on ASE3 also or just add the databases to existing Rep Server (REP1) at ASE1.

3 - If we create DB Rep Defs off of ASE1.pubs1 logical connection, does it hinder performance of Replication Server.

4 - Although your solution is perfect, can you tell me any other alternative solution where we just push databases from ASE2 to ASE3 without actually touching the existing warm standby. Because, we are not concerned about the switch.

Please provide me steps to perform in ASE3 as we dont have anything replicated to it as of yet.

Appreciate your help and support

Thanks & Best Regards

AB

[Mark_A_Parsons]

1 - yes, you need to create a db repdef/sub pair for each replicated db

2 - you can install another repserver if you want, or you can use your current repserver; just depends on your preference and whether or not the current repserver can handle the additional cpu/memory load

3 - when you give the repserver more work to do you obviously (?) affect performance to some degree; the more important question is whether or not your current repserver is at/near its performance limits

4 - did you follow that thread link I provided? did you read Luc's post (within that thread)?  if not, I suggest you go read Luc's post for a different way to setup your replication environment; the fact that you state you're not concerned about the switch leads me to believe that a warm standby solution may be overkill (ie, if you never plan on doing a switch then the WS setup is overkill)

[former_member231251]

Thank You Mark for your invaluable expertise. I will try out couple of options you gave in the test environment and let you know about the details.

Yes, I have read the post you are referrring to, I will try both the options in different test environments and let you know the results.

Meanwhile, please write me down detailed steps to perform the following scenario you suggested.

Steps to be performed in ASE1 and RepServer.

Steps to be performed in ASE3

I am a learner and I need some layman-ish instructions from you.

Hope you understand my plight.

Thanks & Best Regards

AB

[Mark_A_Parsons]

Before you attempt to come up with the necessary commands, you need to decide on what your topology is going to look like.

You've mentioned that you're currently using WS, but have no need to do a switch ... so what was the reason for initially setting up WS?

Attempting to setup a topology like Luc's would require a different set of commands.

You've (basically) stated you want to replicate from ASE1 to ASE2, and then from ASE2 to ASE3; is there a reason why you couldn't replicate directly from ASE1 to ASE3? [That's more of a rhetorical question in that whatever you answer is going to have an effect on your ultimate topology.]

[former_member231251]

Mark,

We already have a warm standby between ASE1 and ASE2 and the possibility of switch is in place but we haven't had the situation to switch yet.

Now the clients wants to replicate ASE2 to ASE3 and asked me to come up with a solution such as another warm standby between ASE2 and ASE3. Currently what we have is a dump and load from ASE2 and ASE3 with Net Backup but they want replication here.

Please give me a solution to replicate databases from ASE2 to ASE3. The third server ASE3 would be used for reporting purposes only and will not be used for fail over switch. The switch will only happen between ASE1 and ASE2 only.

Please let me know the easiest way to accomplish this and provide steps to perform at all the servers involved.

Thanks for your patience and consideration.

Best Regards

AB

[Mark_A_Parsons]

I've already given you a couple solutions ...

1 - create db repdef with the current logical connection as the primary db, then create a db subscription

2 - use Luc's write-up to convert your WS to MSA; at that point you just create new db subs into ASE3 using the db repdefs for ASE1/ASE2

If you don't know how to create a new repserver (if that's what you want), don't know how to add a database to a replication domain, don't know how to add a db repdef/sub ... then I'd suggest you let your manager know so that (s)he can either a) get someone else on the project who knows their way around repserver or b) arrange for some training.

This forum really isn't designed for detailed training lessons and/or designing detailed implementation plans.

[Former Member]

AB,

As you are probably realizing, you have just been interacting with a top SAP Replication Server expert from whom we all are learning quite a bit.

However, as he indicates, this is not a Technical Support, Training or Consulting froum. The purpose of the forum as I understand it is to exchange information. However, it is not a substitute for the above.

Just this morning, I was comenting here on a question that I provided feedback on, that I recommended a particular course of action, while, TS came up with the official response. Sometimes, it does the trick, sometimes it doesn't, however, it is worth the try while you wait.

Help yourself, and God will help you, right?

Regards,

Jean-Pierre