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  • Latest Post - ‏2013-06-14T14:30:31Z by Andrew McCarl
Andrew McCarl
Andrew McCarl
73 Posts

Pinned topic Error SQL1220N when running db2start command

‏2013-06-12T14:52:02Z | db2 dbdsupport hivalue technical-article

The problem is that I cannot start DB2 instance after installation, and get the error


The database manager shared memory set cannot be allocated.

SQL1220N error happens under two conditions.

1. Instance_memory is set to hard value that is too high to be allocated.

2. This error can also be seen even if the instance memory is already set to automatic. For example if the privileged value of zone.max-locked-memory is explicitly set in the operating system by the system administrator, then the same error can be seen during db2start. By default this is not set in the operating system.

Set the dbm cfg INSTANCE_MEMORY value to AUTOMATIC by issuing the following command from a DB2 Command Window as the instance owner:

db2 update dbm cfg using INSTANCE_MEMORY AUTOMATIC

Once this is done, then attempt to start your instance.

If INSTANCE_MEMORY is already set to automatic and you encounter the error again. Then either remove the capping from zone.max-locked-memory; or work with your system administrator to set the privileged limit for "zone.max-locked-memory" high enough for DB2 to start.


This is also covered by the technical article 1396245,


  • Andrew McCarl
    Andrew McCarl
    73 Posts

    Re: Error SQL1220N when running db2start command

    Hello!  We've had a number of clients respond through feedback to our technical documents indicating that they have further questions or comments that require additional dialogue.  Unfortunately, our feedback is anonymous, so unless an email address or other contact information is included, we have no way to get back in touch with you.
    Within DB2 support, the management team asked if we could somehow link our documents to the forums so that we could invite more discussion - like this!   As a start, we chose a small set of  technical articles and "seeded" the forum with initial entries so that we could have a starting place for conversation.  The documents have now been updated with links to the forums as well.  
    Hopefully, we will make DB2 support better by providing more interaction around our technical information!