Problem with HANA System Replication Configuration

[#1]

Hi everyone,

I'am trying to setup a system replication configuration between two developer HANA instances. (This should be a dry run on system replication to upgrade our HANA One Rev 74 to Rev 80 via replication takeover.)

The main specs

SITE_A :

     # Developer HANA Rev 80 (1.00.80.00.391861) hosted on AWS (via SAP CAL)

SITE_B :    

     # Developer HANA Rev 80 (1.00.80.00.391861) hosted on Azure (via SAP CAL)

Main Problem

One registering SITE_B as secondary system (hdbnsutil -sr_register) I get the following error:

error: only system replication chains are allowed with an aditional async secondary site: [primary] <------- [secondary] <---async--- [additional secondary] failed

I think I am missing a very general piece because the message is about a replication chain though I am creating a basic instance to instance replication.

Any help or hint would be great.

The hole story

I followed the documentation:

* http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/9049e009-b717-3110-ccbd-e14c277d8...

*

*

Enable replication mode on SITE_A went without problem:

sid-hdb:/usr/sap/HDB/HDB00> hdbnsutil -sr_state
checking for active or inactive nameserver ...


System Replication State
~~~~~~~~~~~~~~~~~~~~~~~~


mode: primary
site id: 1
site name: AWSDEV80


Host Mappings:
~~~~~~~~~~~~~~




done.

2.Step is to register SITE_B as Secondary System. Therefor I stopped the system and afterwards tried this on SITE_B maschine:

vhcalhdbdb:/vap/usr/sap/HDB/HDB00> hdbnsutil -sr_register --remoteHost=54.77.xxx.yyy --remoteInstance=00 --mode=async --name=SITEB
adding site ...
checking for inactive nameserver ...
nameserver vhcalhdbdb:30001 not responding.
collecting information ...
error: only system replication chains are allowed with an aditional async secondary site: [primary] <------- [secondary] <---async--- [additional secondary]
failed. trace file nameserver_vhcalhdbdb.00000.000.trc may contain more error details.

The log contains:

[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764448 i Basis            TraceStream.cpp(00396) : ==== Starting hdbnsutil, version 1.00.80.00.391861 (NewDB100_REL), build linuxx86_64 not set 2014-05-23 12:00:36 ld7272.wdf.sap.corp gcc (SAP release 20130806, based on SUSE gcc47-4.7.2_20130108-0.15.45) 4.7.2 20130108 [gcc-4_7-branch revision 195014]
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764562 i Basis            TraceStream.cpp(00401) : MaxOpenFiles: 1048576
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764592 i Memory           MallocProxy.cpp(01181) : Installed malloc hooks
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764596 w Basis            Timer.cpp(00660) : Fallback to system call for HR timer
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764599 i Memory           AllocatorImpl.cpp(01219) : Allocators activated
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764601 i Memory           AllocatorImpl.cpp(01235) : Using big block segment size 16777216
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764604 e Configuration    ConfigStoreManager.cpp(00693) : Configuration directory does not exist.
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764607 e Configuration    ConfigStoreManager.cpp(00693) : Configuration directory does not exist.
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764609 i Basis            ProcessorInfo.cpp(00746) : Using GDT segment limit to determine current CPU ID
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764611 w Environment      Environment.cpp(00286) : Changing environment set IMSLERRPATH=/usr/sap/HDB/HDB00/exe//
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764613 w Environment      Environment.cpp(00286) : Changing environment set IMSLSERRPATH=/usr/sap/HDB/HDB00/exe//
[6748]{-1}[-1/-1] 2015-02-03 12:57:01.764617 w Environment      Environment.cpp(00286) : Changing environment set SSL_WITH_OPENSSL=0

Again, any help or hint would be great.

Cheers,

Mathias

[Former Member]

Hi Mathias,

1. Can you check the result of hdbnsutil -sr_state on SITE_B

2. Try the sr_register on SITE_B with the MODE= SYNC or SYNCMEM

We need to see if there is a different errorfor other modes compared to ASYNC mode

Send me the results and we can check accordingly

[Former Member]

Runnig on SITE_B:

vhcalhdbdb:/vap/usr/sap/HDB/HDB00> hdbnsutil -sr_state
checking for active or inactive nameserver ...
nameserver vhcalhdbdb:30001 not responding.
nameserver vhcalhdbdb:30001 not responding.


System Replication State
~~~~~~~~~~~~~~~~~~~~~~~~


mode: none


done.

Test sync and syncmem shows no difference.

vhcalhdbdb:/vap/usr/sap/HDB/HDB00> HDB info
USER       PID  PPID %CPU    VSZ   RSS COMMAND
hdbadm    5208  5207  0.0  12404  2612 -sh
hdbadm    3519  3515  0.0  12408  2636 -sh
hdbadm    7278  3519  0.0  11440  1592  \_ /bin/sh /usr/sap/HDB/HDB00/HDB info
hdbadm    7301  7278  0.0   4664   572      \_ ps fx -U hdbadm -o user,pid,ppid,pcpu,vsz,rss,args
hdbadm    2964     1  0.0 153560 89336 /usr/sap/HDB/HDB00/exe/sapstartsrv pf=/usr/sap/HDB/SYS/profile/HDB_HDB00_vhcalhdbdb -D -u hdbadm

vhcalhdbdb:/vap/usr/sap/HDB/HDB00> hdbnsutil -sr_register --remoteHost=54.77.xxx.yyy --remoteInstance=00 --mode=sync --name=SITEB
adding site ...
checking for inactive nameserver ...
nameserver vhcalhdbdb:30001 not responding.
collecting information ...
error: only system replication chains are allowed with an aditional async secondary site: [primary] <------- [secondary] <---async--- [additional secondary]
failed. trace file nameserver_vhcalhdbdb.00000.000.trc may contain more error details.

vhcalhdbdb:/vap/usr/sap/HDB/HDB00> hdbnsutil -sr_register --remoteHost=54.77.xxx.yyy --remoteInstance=00 --mode=syncmem --name=SITEB
adding site ...
checking for inactive nameserver ...
nameserver vhcalhdbdb:30001 not responding.
collecting information ...
error: only system replication chains are allowed with an aditional async secondary site: [primary] <------- [secondary] <---async--- [additional secondary]
failed. trace file nameserver_vhcalhdbdb.00000.000.trc may contain more error details.

The trace file aren't different as well.

So, I would say there is no difference between the modes.

Thanks a lot.

Cheers.

[Former Member]

Hi Mathias,

I got exactly the same problem today.

Replicating

B1X/hosta 97.04 to B1X/hostb 112.02

When I ran hdbnsutil -sr_register on hostb, I got the same error as you.

I manged to resolve the problem.

My issue was B1X was initially a copy of our production system which has replication on.

So when I ran hdbnsutil -sr_state on my primary server, it showed replication config from my Production system!

To fix this. I shut down HANA on both systems.

Ran "hdbnsutil -sr_cleanup –force" on both system.

Next I started HANA on hosta. Enabled replication on hosta then ran hdbnsutil -sr_register on hostb.

This time I did not get the error.

Replication still had problems because I was replicating SPS9 to SPS11 and there is a bug, see

"2312539 - Near Zero Downtime Upgrade To SAP HANA Database SPS11 With ASYNC Replication Mode Doesn't Work"

On siteB I added

[system_replication]

enable_send_ack_in_async_mode = false

to  global.ini

then restarted HANA on siteB , now the replication started!

Regards

Tom