n can be 8192, 16384, 32768, or 65536. The default value is 8192.
DBSizesAllowed lists the database block sizes (in bytes) that you can select when creating a database.
For more information about creating and managing databases, see the Configuring Databases section of the “Configuring InterSystems IRIS” chapter in System Administration Guide.
Changing This Parameter
On the Startup page of the Management Portal (System Administration > Configuration > Additional Settings > Startup), in the DBSizesAllowed row, select Edit. Select each desired database block size. You cannot clear 8192.
When you enable an additional database block size, you must allocate memory for that block size using the globals parameter. This allows InterSystems IRIS® data platform to create the needed pool of global buffers for that size.
Instead of using the Management Portal, you can change DBSizesAllowed in the Config.StartupOpens in a new tab class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF file section of the “Introduction to the Configuration Parameter File” chapter in this book).
globals parameter in the [Config] section of this reference.
Configuring Databases in the “Configuring InterSystems IRIS” chapter in System Administration Guide.
Allocating Memory to the Database and Routine Caches in the “Configuring InterSystems IRIS” chapter of System Administration Guide
Large Block Size Considerations in the “Configuring InterSystems IRIS” chapter in System Administration Guide.