nameserver config role maximum number

[Former Member]

Hi All,

I have a doubt, I have seen that maximum number of nameserver configured as master as three. My doubt is that what if we have more than three?

Is it not supported or is it not a best practise?

Message was edited by: Tom Flanagan

[srinivasan_vinayagam]

Hi ,

Three Name Server is sap recommended, you can find this from HANA certification documents too.

Regards,

V Srinivasan

[former_member639157]

Hi Srinivasan,

Its not only recommendation, that is the hard limit as of now.

Regards,

S Sumanth GV

[Former Member]

Hi,

I did try with a higher number of name server and it worked.

Probably sap support can advise more on this.

[Former Member]

Yeah true I think then probably we need to check on this whether we can have since there is a certification question as well on this.

[Former Member]

Hi,

can you please tell me in whic situation you have encoutnthe above configuration ?

i mean

why three/more than three ameservers are required ?

I just wnated t understand it.

Regards,

Pavan Gunda

[Former Member]

lets take this case,

Host A,B,C,D,E,F and standby G

if A,B and G are defined as masters now if the topology has changed and then standby host is on the non master then later one when we do restart there will be two node failovers.

This we have seen it.

But anyways coming back to my question there is no hard and fast rule or a recomendation from SAP saying that we should be having only 3 master nameservers defined right.

[former_member639157]

As far as I know, there is a restriction that you can only define up to 3 master name-server. This might change in future releases.

Cheers,

S S umanth GV

[Former Member]

Hi Subramanya,

Request you to please share the official word on this, where is the restriction defined?

[former_member639157]

Hi,

You can look up this information in SAP HANA Admin guide which is public. MASTER is a type of name server role and as of now you you only 3. That means when you install your distributed system having more than 3 nodes then automatically up to 3 nodes will be configured as master name server.

I am sure there might be a hard way to come around this and configure more than 3 nodes with master role which might not be supported by SAP or work at all... If this is something your architecture group is asking this to you then I would suggest to open an SAP message.

Hope this clarifies.

Regards,

S Sumanth GV

[Former Member]

Subramanya,

If you read the whole thread i did paste the text from the admin guide .

Thanks for your susggestion, i was assuming that some kind of response would be out here.

[former_member639157]

I did not read the whole thread, I assumed you haven't got your answer yet.

Currently, as many as 3 name servers can be configured to be the master.  That is the limit!

Hope this answers your concern

[srinivasan_vinayagam]

Hi,

Name Server:

Up to 3 hosts can be configured as MASTER Name Servers (using a “MASTER 1, MASTER 2, MASTER 3” naming designation), while others have to be configured as “SLAVE”. However, in steady state, only one of the “MASTER n” configured hosts has its actual Name Server role as “MASTER” while all other hosts have their actual Name Server roles as “SLAVE”. The MASTER Name Server is responsible for assigning storage/data volumes to active Index Servers at the time they start up.

If the MASTER Name Server host fails, one of the remaining hosts configured as a “MASTER n” Name Server becomes the active MASTER Name Server.

.

Its possible more than three but not good practice

[Former Member]

Srini,

Not a good practice is this a general opinion or else from practical perspective?

What are the pros and cons , request you to please share your experiences?

[Former Member]

This is what the documentation says,

Nameserver Role (Configured)

Specifies the host's configured role as name server

The following roles are possible:●

MASTER 1, MASTER 2, MASTER 3

When you install a distributed system, up to three hosts are automatically configured as master name servers. The configured namesever role of these hosts is MASTER 1, MASTER 2, and MASTER 3.●

SLAVE

Additional hosts in your system are configured as slave name servers. The configured nameserver role of these hosts is SLAVE.

Nameserver Role (Actual)

Specifies the host's actual role as name server

The following roles are possible:●

MASTER

During system start-up, one of the hosts configured as master name servers (that is, those hosts with configured name server role MASTER 1, MASTER 2, or MASTER 3) is designated to be the active master name server. The actual nameserver role of this host is MASTER. This master name server assigns one volume to each starting index server (those with actual role MASTER or SLAVE), or no volume if it is a standby host (actual indexserver role STANDBY).

If this active master nameserver host fails, one of the remaining hosts configured as a master name server becomes the active master name server.●

SLAVE

The actual nameserver role of the remaining hosts configured as master and slave hosts is SLAVE.

But it doesnt say whether it is mandatory or not?