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Issue while scaling with metadata in volume

Hi Team, As mentioned in the artical it is possible to mount volume in kubernetes for Denodo metadata and depending on the storage class we could persist across deployments. However there is a teething problem with volume mount. With the volume metadata configuration, if you scale the deployment, the second replica will fail with "*Another instance of Derby may have already booted the database /opt/denodo/metadata/db/dbmetadata*" error. I guess this is obvious considering the first replica has already started the derby instance on mounted volume. Shouldn't Denodo ignore this error and use the derby instance which is already started as the metadata database? Please provide your feedback. Regards, Sripathi
user
10-09-2021 04:22:26 -0400
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1 Answer

Hi, Since the purpose of persisting metadata when scaling a deployment is to not have a shared metadata folder with different instances, I will want to have a separate volume mounted for each instance. However with the current setup you are loading the same metadata folder with derby databases in two different denodo instances so the derby databases are overlapping and creating the error mentioned. One way I might resolve this issue you are experiencing, would be to keep the metadata in an external database. For overview of how to do this, please check out the [Storing the Metadata on an External Database](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/server_configuration/storing_catalog_on_external_database/storing_catalog_on_external_database) section of the Virtual. Hope this Helps!
Denodo Team
17-09-2021 15:24:03 -0400
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