[dspace-tech] Issue with Two Dspace servers with common NAS for bitstore (assetstore)

[Ravi Konila]

Hi,

 

Hope all are doing good.

 

I have successfully installed two Dspace 7.6 servers with a common NAS storage connected to both the servers used for bitstore/assetstore.

Both the servers works fine individually with the shared storage. But items/community/collection created in one is not visible in other one.

Please note that, both the servers use same Postgresql 15 server/db.

 

The Dspace configurations are identical (dspace and dspace-ui). Both can communicate successfully to common Dspace database.

 

Could anyone please clarify, if someone has done & configured load balancing or HA between two Dspace servers using shared storage (NAS).

Please guide me to take this forward.

 

Thanks in advance

 

With Warm Regards
Ravi Konila

[Mark H. Wood]

On Tue, Jul 25, 2023 at 10:14:10PM +0530, Ravi Konila wrote:
> I have successfully installed two Dspace 7.6 servers with a common NAS storage connected to both the servers used for bitstore/assetstore.
> Both the servers works fine individually with the shared storage. But items/community/collection created in one is not visible in other one.
> Please note that, both the servers use same Postgresql 15 server/db.
>
> The Dspace configurations are identical (dspace and dspace-ui). Both can communicate successfully to common Dspace database.
>
> Could anyone please clarify, if someone has done & configured load balancing or HA between two Dspace servers using shared storage (NAS).
> Please guide me to take this forward.

I have not attempted this. But I think that the two instances must
also share a single Solr instance.

--
Mark H. Wood
Lead Technology Analyst

University Library
Indiana University - Purdue University Indianapolis
755 W. Michigan Street
Indianapolis, IN 46202
317-274-0749
www.ulib.iupui.edu

[Ravi Bhat]

Hi Mark, 

Thanks for the suggestion but still the same problem. 

I have tried below

1. Single solr service but still same problem, but I need solr also in HA mode

2. Kept Dspace backend in common NAS but can specify only one frontend URL and one backend URL in local.cfg. Only one DSpace instance works at a time, the other one shows error 500. But again items/collections/communities created in one cannot be seen in another even though, DSpace backend is common to both the frontends. 

Does anyone have any idea or suggestion on at least DSpace frontend HA with a common DSpace backend?

Regards

Ravi Konila

[DSpace Technical Support]

Hi Ravi,

I've not done this myself before, but you might want to look closely at the underlying error behind that 500 exception.  Sometimes a simple configuration issue can be the cause of the 500.

Here's how to find the underlying error: https://wiki.lyrasis.org/display/DSPACE/Troubleshoot+an+error#Troubleshootanerror-DSpace7.x(orabove)

Here's common causes for 500 exceptions: https://wiki.lyrasis.org/display/DSDOC7x/Installing+DSpace#InstallingDSpace-%22500ServiceUnavailable%22fromtheUserInterface

One other thing to check is that the backend (REST API) "trusts" the User Interface.  This is controlled by the "rest.cors.allowed-origins" setting (in the rest.cfg). That setting must list all web-based clients which are using the REST API, otherwise they may be blocked with a 500 exception.

Tim

[Ravi Konila]

Hi Tim

 

Thanks for the reply.

 

What should be dspace.ui.url and solr.server (in local.cfg) since I am using two frontends in two different servers?. Dspace backend is in common NAS mounted on /dspace.

I am only confused how do I make my backend pointing to frontend since there are 2 frontends.

 

Individually, each Dspace instance works fine. But how do I load balance them? at least I need to load balance front end UI.

 

Please note my postgres servers are in already HA in two different servers.

 

With Warm Regards
Ravi

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[Raghwendra Narayan]

Hi Ravi,

U can use main DB to both front end.  It will work 💯.  I am using similar configuration.

Regards.

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[Ravi Konila]

Hi Raghwendra

 

Could you please elaborate on what you are suggesting. My postgres is already in HA and I do not have any problems with the db.

If you are referring DB as Dspace Backend, it is already common to both the frontends.

 

With Warm Regards
Ravi K.
Ph: +91-9901072688

[Mark H. Wood]

On Sun, Jul 30, 2023 at 10:32:43AM -0700, Ravi Bhat wrote:
> Hi Mark,
> Thanks for the suggestion but still the same problem.
>
> I have tried below
> 1. Single solr service but still same problem, but I need solr also in HA
> mode

Again, not something I have attempted. If you need HA Solr then read
up on "Solr Cloud". Your cores become "collections" replicated across
several Solr instances. (This is orthogonal to "sharding": each core
in a collection can hold replicas of all records.)

When you have this working, I'm sure we would appreciate hearing the
details and your experience.

[Ravi Bhat]

Hi Mark & Tim

I have installed Solr cloud successfully but I am not able to understand where to copy Dspace Solr files. Tried to copy them to the data location as well as to cloud/solr location but Solr doesn't recognize them. Any idea where to place Dspace Solr files in Solr cloud scenario?

Thanks for support

Regards

Ravi

[Mark H. Wood]

On Sun, Aug 06, 2023 at 09:14:50PM -0700, Ravi Bhat wrote:
> I have installed Solr cloud successfully but I am not able to understand
> where to copy Dspace Solr files. Tried to copy them to the data location as
> well as to cloud/solr location but Solr doesn't recognize them. Any idea
> where to place Dspace Solr files in Solr cloud scenario?

SolrCloud works differently. You cannot simply copy an empty core
into a Cloud instance; collection configurations are installed in
Zookeeper, which will distribute them to all of its dependent
Solr instances. I would start reading at
https://solr.apache.org/guide/solr/latest/deployment-guide/solr-control-script-reference.html#collections-and-cores
and get some practice with a non-production cloud first.