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ECC 6.0 installation on Sybase and AIX 7.1 using Power HA

Hello Experts,

We have a requirement wherein we need to install ECC 6.0 EHP 6 Production system on Sybase and AIX 7.1 and using Power HA(earlier known as HACMP).

We are required to install database on let's say HOST A, and CI on HOST B. Both HOST A and HOST B are in a mutual fail over cluster,as prepared by hardware vendor.

Being new to High availability installations on SAP, we would initially want to know if for this type of installation we need to go for HA option in sapinst/SWPM or it should be the distributed system installation, on different hosts?

In HA installation we have an ERS (enqueue replication server) installation option which we do not want to install,so please let us know if in HA installation option, ERS is a mandatory installation.

Any suggestions for file systems(mount points,shares) in database host and CI would be highly appreciated.

Just to add that we have gone through installation guides and many other SCN and help.sap.com links, but could not find concrete information and got further confused.

Your help and guidance in this regard will be highly appreciated.

Regards,

Bharat

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4 Answers

  • Best Answer
    author's profile photo Former Member
    Former Member
    Posted on Aug 27, 2013 at 01:02 PM

    Hi Bharat,

    You can definitely have below scenario without ERS server.

    Node A : DB+CI

    Node B: ASCS

    Node C: APP

    Where Node A and Node B are in cluster and Node C is not in cluster.

    Your SPOF are DB and ASCS.

    Here even you CI is behaving as a normal APP server.

    Since your ASCS includes Message server and Enqueue server(Lock Table)

    it is not mandatory to have ERS as part of cluster but it is SAP best practice

    to install ERS as if something happens to your lock table in ASCS instance then

    you have its replica to retain back the lock entries.

    So your cluster should look like below as per deepak's comment.

    Node A : DB+CI+ERS

    Node B : ASCS

    Node C: APP

    Thanks and Regards,

    Kunal Gahlot

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  • Posted on Aug 27, 2013 at 01:49 AM

    Hi Bharat,

    For HA setup on AIX with Sybase you can follow this

    1) Node A: DB instance + ERS + CI
    2) Node B: ASCS +APP

    DB instance and ASCS instances should be part HACMP.

    For Files systems
    1) Include all the DB file systems in cluster
    2) Include /sapmnt & /usr/sap/trans in cluster

    Rest other file systems can be kept outside cluster.

    Some basic information on file system based on Sybase ASE can be found in my blog which is
    based on HPUX.
    http://scn.sap.com/community/sybase-ase/blog/2013/08/06/things-to-consider-when-you-plan-to-install-erp-60-ehp6-with-sybase-ase-on-hpux

    Additionally refer Installation guide , section HA setup.


    Hope this helps.

    Regards,
    Deepak Kori

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    • Hi Bharat,

      What if we do not install ERS, will it still be possible to build a system without ERS?

      In absence of ERS there is a possibility of data loss during failover. ERS basically will hold the enqueue table entries. During failover these entries gets moved and updates are not lost during the process.

      Hope this helps.

      Regards,

      Deepak Kori

  • author's profile photo Former Member
    Former Member
    Posted on Aug 27, 2013 at 08:30 AM

    >> In HA installation we have an ERS (enqueue replication server) installation option which we do not want to install,so please let us know if in HA installation option, ERS is a mandatory installation.

    Yes, you must to install ERS instance if you want to have HA. Also you need to configure ERS as cluster resource and adjust anti-collocation option. If you don't want to setup ERS as cluster resource please read about polling concept.

    High Availability with the Standalone Enqueue Server

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  • author's profile photo Former Member
    Former Member
    Posted on Sep 10, 2013 at 10:23 AM

    Hi All,

    Thank you Deepak and Ruchit for your valuable inputs and suggestions.

    We now have APP servers ready on Node C and Node D,and we are in the process of patching the system.We are planning kernel upgrade and will be copying the new kernel in /sapmnt/SID/exe file on CI/ASCS instance(NODE B).

    and for that, what i understand i should do is

    1.run stopsap command on Node C and D(Application Severs)

    2.run stopsap on Node B(CI) and proceed to upgrade kernel and adjusting permissions(after taking kernel backup).

    3.run startsap command in the reverse order i.e Node B,D and C.

    Please let me know if the above mentioned steps are ok to proceed.Also does kernel upgrade require individual and manual kernel replacement on CI and both app servers?

    Now since CI Node(Node B) is a part of cluster,do i need to make any changes in cluster settings before stopping SAP?

    Also we have SAP license(Standard and Maintenanace) applied on NODE B(CI+ASCS) of the cluster via slicense,but have not applied license to other cluster node NODE A(DB+ERS),so the only way to do that is would be a manual switchover?

    Thanks again everyone for your help and guidance.

    Regards,

    Bharat Pasricha

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    • Former Member

      Hi Bharat,

      The steps are okay.

      Kernel upgrade doesn't have to be manual if sacpe steps are defined in start profile of the app servers since the start of SAP instance would take care of replication in case it finds any difference in the relevant binaries.

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