Release Notes

|5.28 Chapter 6. Verifying the Installation on AIX

|5.28.1 Workarounds in NFS environments

|This section describes workarounds to known problems when running DB2 Data |Links Manager for AIX in NFS environments that do not appear in the current |documentation. These problems are NFS-specific and have nothing to do |with DB2 Data Links Manager or DB2 Universal Database. |

|Additional NFS caching issues

|Two different caches are maintained on the NFS client for AIX. The |NFS client maintains a cache with attributes of recently accessed files and |directories. The client also optionally supports a data cache for |caching the content of files on the client.

|The attribute caching process sometimes produces an unusual condition on an |NFS client after a READ PERMISSION DB file is linked. Users are |sometimes able to access a READ PERMISSION DB file without an access control |token if these users were connected to the machine before the file was |linked. Use one of these methods to reduce the likelihood of |unauthorized file access:

|

• |Use the touch command on the file before executing the SQL |INSERT statement to set the link.
• |Use the touch command on the directory containing the |file.
• |Use the mount command with one of the five attribute cache |configuration parameters (actimeo, acregmin, acregmax, acdirmin, |acdirmax) to minimize the time that cached attributes are retained after |a file or a directory is modified. |

|You are most likely to observe unauthorized access of READ PERMISSION DB |files during Data Links function testing since only one file is linked and |there is little NFS activity. You are less likely to encounter this |scenario in a production environment since NFS activity is heavy and the NFS |attribute cache usually does not retain the attributes for all linked |files. |