While looking at the database structure of an application I am using I recognized that it uses 3 different databases on the same MS-SQL server instance for different things.

The first one contains the main data that changes rarely. The second one contains event logs with high traffic and volume and the last one is an archive database for old event logs.

I was wondering what the benefit of this structure might be, because the databases are running on the same instance and the database files are located on the same disk. Therefore I would not expect any performance improvements from this.

I thought, maybe I am overlooking something and somebody can point me to benefits that I did not think of.

Update: Some good points were made regarding maintenance and security. But I am still wondering if it is possible to get a performance improvement.

A more general question would be: Can the performance of one table suffer from other large tables in the same database (due to fragmentation or for some other reason) or are those effects probably negligible.

While looking at the database structure of an application I am using I recognized that it uses 3 different databases on the same SQL Server instance for different things.

The first one contains the main data that changes rarely.

The second one contains event logs with high traffic and volume and the last one is an archive database for old event logs.

I was wondering what the benefit of this structure might be, because the databases are running on the same instance and the database files are located on the same disk. Therefore I would not expect any performance improvements from this.

I thought, maybe I am overlooking something and somebody can point me to benefits that I did not think of.

Update: 
Some good points were made regarding maintenance and security. But I am still wondering if it is possible to get a performance improvement.

A more general question would be: Can the performance of one table suffer from other large tables in the same database (due to fragmentation or for some other reason) or are those effects probably negligible.

While looking at the database structure of an application I am using I recognized that it uses 3 different databases on the same MS-SQL server instance for different things.

The first one contains the main data that changes rarely. The second one contains event logs with high traffic and volume and the last one is an archive database for old event logs.

I was wondering what the benefit of this structure might be, because the databases are running on the same instance and the database files are located on the same disk. Therefore I would not expect any performance improvements from this.

I thought, maybe I am overlooking something and somebody can point me to benefits that I did not think of.

While looking at the database structure of an application I am using I recognized that it uses 3 different databases on the same MS-SQL server instance for different things.

The first one contains the main data that changes rarely. The second one contains event logs with high traffic and volume and the last one is an archive database for old event logs.

I was wondering what the benefit of this structure might be, because the databases are running on the same instance and the database files are located on the same disk. Therefore I would not expect any performance improvements from this.

I thought, maybe I am overlooking something and somebody can point me to benefits that I did not think of.

Update: Some good points were made regarding maintenance and security. But I am still wondering if it is possible to get a performance improvement.

A more general question would be: Can the performance of one table suffer from other large tables in the same database (due to fragmentation or for some other reason) or are those effects probably negligible.