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DB2 - Maximum single container data file size

emil_tkac2
Explorer
0 Kudos

Hello all,

Can you please advice me what is the maximum size of single DB2 container (data file) ?

Automatic storage management is activated for the database and also for tablespaces with only one storage path defined. Currently, for largest tablespace, there is only one container existing and has size already 215GB.

I know that it is not possible to add datafile manually if autostorage is activated, so how can I force creation of new container ?

I am quite new with DB2, so I will appreciate your answers.

Regards,

Emil

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Answers (1)

Answers (1)

Frank-Martin
Product and Topic Expert
Product and Topic Expert
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Hi Emil,

when using autostorage you can not manually add containers to a tablespace. The container size is only limited by OS, user and file system restrictions.

Large containers do not cause a performance penalty if file system caching is switched off for your tablespaces. If you have enabled file system caching for your tablespaces ( for example because your filesystem type does not support DIO/CIO ) very large containers may cause a problem due to inode contention on some filesystems. You can use the DB2 registry variable DB2_SET_MAX_CONTAINER_SIZE to force DB2 to create a new container for an autostorage tablespace when the maximum size is reached. A good value may be around 100 GB in bytes.

Regards

Frank

emil_tkac2
Explorer
0 Kudos

Hi Frank,

Thanks for your hint which is useful for me, as OS and file system restrictions should be OK. I thought that this parameter is automatically active as of DB2 V9.5for SAP environment (if DB2WORKLOAD=SAP is set) with default value 20GB (DB2_SET_MAX_CONTAINER_SIZE = 20000000000).

But in the note [https://service.sap.com/sap/support/notes/1338314] I can read that this parameter is deactivated as of DB2 9.7 GA .

Do you know what happens if container size is already 215GB and I will set DB2_SET_MAX_CONTAINER_SIZE now to 100GB ? Or can I just specify higher value than actual size 215GB ?

Regards,

Emil

Frank-Martin
Product and Topic Expert
Product and Topic Expert
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Hi Emil,

you are right. This setting was automatically set in earlier Fixpacks of V9.5. However many customers complained about too many containers and most customers are using DIO/CIO anyways. 20GB may have been too small in any case.

I have not tried to activating this parameter after the limit has exceeded but I would expect that the next extent allocation triggers the creation of a new container. Can you give it a try?

Regards

Frank

emil_tkac2
Explorer
0 Kudos

Hi Frank,

I cannot give it a try, as I don't have any sandbox system for such testing.

Did anyone else have tested it ?

Regards,

Emil