Warnings in Informix database log

Question

I checked the log sbaserver.log of an Informix database running on AIX and received 3 warnings.

1. 06:59:23 WARNING: If you intend to use J/Foundation or GLS for Unicode feature (GLU) with this Server instance, please make sure that your SHMBASE value specifies in onconfig is 0x700000010000000 or above. Otherwise you will have problems while attaching or dynamically adding virtual shared memory segments. Please refer to Server machine notes for more information.

2. 06:59:25 Warning: ONCONFIG dump directory (DUMPDIR) '/infdump' has insecure permissions

3. This message about the physical log:

   08:08:10  Performance Advisory: Based on the current workload, the physical log might be too small to 
   accommodate the time it takes to flush the buffer pool.
   08:08:10   Results: The server might block transactions during checkpoints.
   08:08:10   Action: If transactions are blocked during the checkpoint, increase the size of the physical log to at least 229992 KB.
   

We check and see whether physical logging is too small.

Please check whether we need to extend it or not.

Can you explain why the system shows these warnings and what I should do?

Answer 1

The first message is reasonably self-explanatory. There is a parameter in your ONCONFIG file that is called SHMBASE. If it is not zero, then on your 64-bit AIX version, the value specified should be at least the value 0x700000010000000 (which, be it noted, shows 15 of 16 possible hex digits; it might be written 0x0700000010000000 more clearly). Presumably, you have another (non-zero) value set in your ONCONFIG file.

The second message indicates that the permissions on the directory /infdump are not set appropriately. It almost certainly means they are too lax. Under normal circumstances, the directory should be owned by user informix, belong to group informix, and should not have public write access at minimum and normally should have no public access whatsoever. Thus, 775 is the most lax possible permissions; 770 is recommended.

The third message indicates that you should be setting your physical log to 230 MiB, give or take a little. The system thinks that if you set it smaller than that, it may not have enough space to avoid blocking on a checkpoint (which is temporarily bad for transaction throughput on the Informix server). That's a fairly hefty physical log. You may decide that you can live with that warning. But it is a guideline for setting the physical log size, and if you can spare the disk space, it will probably work a little better for you at peak load.