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

Could you reach for a solution out? I have the same issue in a newer version, SP85

- I followed the same guideline.

- Both systems have exactly the same configuration (different OS parameters, of course).

[PRIMARY] known as PRIME >> $ HDB version

HDB version info:

  version:             1.00.85.00.397590

  branch:              NewDB100_REL

  git hash:            not set

  git merge time:      not set

  weekstone:           0000.00.0

  compile date:        2014-11-12 12:39:22

  compile host:        ld7272.wdf.sap.corp

  compile type:        opt

[SECONDARY] known as CONTINGENCIA >> $ HDB version

HDB version info:

  version:             1.00.85.00.397590

  branch:              NewDB100_REL

  git hash:            not set

  git merge time:      not set

  weekstone:           0000.00.0

  compile date:        2014-11-12 12:39:22

  compile host:        ld7272.wdf.sap.corp

  compile type:        opt

--- X --

STEPS TO ENABLE REPLICATION

--- X ---

From PRIME

hdbnsutil -sr_enable --name=PRIME

From CONTINGENCIA

hdbnsutil -sr_register --remoteHost=<PRIME_hostname> --remoteInstance=00 --mode=sync --name=CONTINGENCIA

adding site ...

checking for inactive nameserver ...

nameserver <CONTINGENCIA_hostname>:30001 not responding.

collecting information ...

// This command runs forever....

--- X --

Checkin from PRIME

--- X ---

$ hdbnsutil -sr_state

checking for active or inactive nameserver ...

System Replication State

~~~~~~~~~~~~~~~~~~~~~~~~

mode: primary

site id: 1

site name: PRIME

Host Mappings:

~~~~~~~~~~~~~~

<PRIME_hostname> -> [PRIME] <PRIME_hostname>

<PRIME_hostname> -> [CONTINGENCIA] <CONTINGENCIA_hostname>

$ hdbcons -e hdbindexserver "replication info"

SAP HANA DB Management Client Console (type '\?' to get help for client commands)

Try to open connection to server process 'hdbindexserver' on system '<SID>', instance '<instance>'

SAP HANA DB Management Server Console (type 'help' to get help for server commands)

Executable: hdbindexserver (PID: 37303)

[OK]

--

Dumping replication statistics ...

Replication Primary Information

===============================

System Replication Primary Configuration

[system_replication] logshipping_timeout                      = 30

[system_replication] enable_full_sync                         = false

[system_replication] preload_column_tables         = true

[system_replication] ensure_backup_history         = true

[system_replication] enable_ssl                    = off

[system_replication] datashipping_snapshot_max_retention_time = 7200000000

- lastLogPos               : 0x2bd106c0

- lastLogPosTimestamp      : 06.02.2015-12.10.55 (1423224655944076)

- lastSavepointVersion     : 14684

- lastSavepointLogPos      : 0x2bd0fb02

- lastSavepointTimestamp   : 06.02.2015-12.07.58 (1423224478129835)

0 session registered.

[OK]

--

[EXIT]

--

[BYE]

So no replication can be established.

I've checked at SAP HANA STUDIO >> LANDSCAPE >> SYSTEM REPLICATION from PRIME and both servers are shown, but nothing else.

- Do I have to check anything else on both systems?

- Which LOG file do I have to review?

Thanks!

[Former Member]

Hi Sergio,

I'm sorry but i couldn't resolve my problem yet and I have no good advice for your problem.

Maybe the adminstration guide can help you. (But I'm pretty sure that you already read through it) http://help.sap.com/hana/SAP_HANA_Administration_Guide_en.pdf

Two points I missed for some time:

# Do you configured the hostname resolution as described in 4.1.3.16 of the guide.

# Are the hostnames of both systems really different? On my machines DEV HANA hostnames are every time vhcalhdbdb and HANA ONE instances are every time hanaserver. And i think

collecting information ...

// This command runs forever....

indicates that that hostNames could not be resolved correctly.

Cheers,

Mathias

[Former Member]

Hi again Mathias.

I'm also sorry because of you

Well, as you said, I read about this in the Ad. Guide with no success.

And yes, hostnames are different in both systems.

However the command runs forever and it seems a hostname resolution problem, through netstat command I can see an "ESTABLISHED" messages in both systems, so there's kind of communication!

I'm still stuck on that....

THANKS!

[Former Member]

Hello Sergio,

How are you ?

I have exactly the same issue.... after registering the secondary site.

checking for inactive nameserver ...

nameserver lr002:30001 not responding.

collecting information ...

"// This command runs forever...."

and as well I have established connection.

1st Site

hdbnamese 61026 pr0adm   31u  IPv4 3445012

0t0  TCP lp002pr0:30102->lr002:64334 (ESTABLISHED)

2nd site

hdbnsutil 28773 pr0adm   13u  IPv4 89708833

0t0  TCP lr002:64334->lp002pr0:30102 (ESTABLISHED)

Did you sovle the issue ?

Cheers

Mohamed

[Former Member]

Hi Guys,

The sr_register command appearing to hang can also indicate an MTU size problem on the network connection between the nodes. If you are using Jumbo frames then drop down to an MTU of 1500 and see what happens.

Sander