HANA can I have more than 1 indexserver per tenant database?

[Former Member]

Hello,

1) When we CREATE a tenant database, do we create it clean and then add the services or is it created with the inexserver already? If the latter, what does this statement from the Admin guide mean?

I was always under the impression, that we have one indexserver per tenant. Correct me if I am wrong.

2) This an unrelated question. Let's say one of my hosts which has a system database, and two tenants fails. Standby server takes over. Now, will the standby imitate the architecture of the failed server? (that is how would it continue to perform the operations with the structure of a system DB and two tenants? Now, I am assuming that a standby is typically configured having 1 active name server and 1 inactive index server when not involved and my system that failed would have at least 3 index servers)

[prabhjotsingh]

Can i have more than one index server per tenant database

[dvankempen]

Yes, you can!

The use case for configuring multiple indexserver services on a single physical/virtual host are probably problematic. However, for a multiple host (a.k.a. distributed or scale-out) system, configuring multiple indexserver services for the tenant database (e.g. one per host) makes perfect sense.

[lbreddemann]

Hmm... sounds as if you mix up the indexserver with nodes.

While indexserver, nameserver, compileserver etc. really are services that provide the respective functionality, the failover mechanism is based on shared persistency.

The mentioned services (at least some of them) have their assigned piece of storage where they find the data they work on.

Once a node gets recognized as unavailable the services that depend on the storage assigned to the failed node cannot continue to work.

So these services will be stopped, the storage gets assigned to the standby node and the services get restarted there.

Since a tenant database uses indexserver processes just as a non-MDC database, there is no difference the possibility for a stand-by setup.

You can even decide on how you want to distribute the different tenant DB  processes over your HANA cluster - that's where the ADD <service> command comes into play.

Check https://hcp.sap.com/content/dam/website/saphana/en_us/Technology%20Documents/SPS09/SAP%20HANA%20SPS%... on that.

- Lars

[Former Member]

Yes, sorry. I do mean index server as a service. But the question still remains: when we add a new tenant to our system, is it automatically created with the indexserver service or do we add the service later? And is it true that there is only 1 indexserver service per tenant?

[lbreddemann]

Hmm... I thought I answered the first question and provided a link to the material for the second one...

Anyhow, once you create a tenant DB there must be at least one indexserver process so this is added automatically.

If you want to have multiple indexserver processes - that is a scale-out scenario - you'll have to add them.

- Lars

[Former Member]

I think I just found an answer to my question. In the capture below tenants 1 and 2 on the same SID system are scaled out on two hosts so each has 2 index servers. I was just confused about the scaleout scenario. For some weird reason I was thinking about scale out as adding a new host with NEW tenants on it, while in fact it can be either that or stretching the tenants across multiple hosts.