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For the most part, the following discussions apply to both Windows and UNIX systems except for the guidelines to repartition hard disk devices. On a Windows system, input/output (I/O) is buffered by default, but Oracle Tuxedo sets a certain system-level flag to change the default. Thus, all I/O for Oracle Tuxedo processes is unbuffered, meaning that you do not need to make any special disk-space arrangements on a Windows system.The Oracle Tuxedo system provides a facility called the Disk Management Interface (DMI), which manages logical files within a single disk device or set of devices. The DMI performs tasks such as storing binary configuration tables and the transaction log. You can use it to create, initialize, or destroy entries in the Oracle Tuxedo filesystem. To access the DMI, use the tmadmin(1)administrative commands described in the Oracle Tuxedo Command Reference.Space outside the OS filesystem is usually referred to as raw disk space. Not only is I/O faster when done by system calls reading directly from and writing directly to device special files on raw disks, but a physical write() occurs right away. When using an OS filesystem, Oracle Tuxedo cannot predict or control the precise moment at which a write() is done. When using raw disk space, however, Oracle Tuxedo has accurate control of the write operation, which is particularly important for entries in the Oracle Tuxedo transaction log. Also, when multiple users are accessing the system, being able to control the write operation is important for assuring database consistency.If you decide to use raw disk space for your Oracle Tuxedo application, and you are using a UNIX system, you may find that the hard disk devices on your system are fully allocated to filesystems such as / (root) and /usr. If that is the case, you must repartition your hard disk device in order to set aside some partitions for use as non-OS filesystems. For repartitioning instructions, refer to the system administration documentation for your platform.Listing D‑1 shows a sample VTOC and UDL diagram for a bankapp (sample application) configuration on a single machine.Listing D‑1 VTOC and UDL DiagramThe Oracle Tuxedo application administrator must make sure raw disk slices are available as needed on each node participating in an application. Table D‑1 lists the size of each element in the Oracle Tuxedo filesystem.
The amount of space required for the TUXCONFIG file must be larger if there are more entries in the configuration file, UBBCONFIG, than in the bankapp sample application. The administrator is encouraged to allocate additional space for dynamic reconfiguration and growth of the application. The default block size assumed by the crdl subcommand of tmadmin is 1000 blocks (512000 bytes assuming 512-byte blocks), which should be adequate for the initial installation.If your Oracle Tuxedo application uses /Q for store-and-forward queue management, your queue space can be listed in the same UDL as the one used to store the TUXCONFIG file and the TLOG, and managed by the Oracle Tuxedo VTOC.