A new On Disk Structure (ODS) is available with Domino 8. This is an update from ODS43 to ODS48. First of all, upgrading applications (formerly called databases) to ODS48 is completely optional and requires the addition of a notes.ini setting on the server (or client).
This setting is: Create_R8_Databases=1.
If you enable this in a global configuration document, the Pre-8 servers will ignore it and will not be affected by having this setting. This can be a good way to propogate this to all (or many) of your servers prior to upgrading to Domino 8. As with previous ODS upgrades, a copy-style compact is required to upgrade all databases to the new ODS. However, the applications will not be upgraded automatically with a copy-style compact as they were with previous ODS upgrades unless the notes.ini setting is enabled.
What do I get with the new ODS?
1. There are some general I/O enhancements and "folder optimizations".
2. The maintaining of a "Database Names List" used for user renames
With ODS48, a list of all of the Readers and Authors in an application is maintained at a high level by default. This will improve the efficiency by which AdminP can process the user rename requests ("Update User Name in Reader and Author Fields"). If AdminP finds the user's name in the Database Names List, it will continue processing that application. Otherwise it will skip the application.
3. Design Compression
This database property (found on the Advanced tab of ODS43 and ODS48 database properties) will compress the design notes. IBM states that mail files based off of mail8.ntf will only utilize 11MB instead of 25MB if design compression is enabled. As you can see, 14MB of savings per mail file can be huge. This feature is disabled on all databases by default. However, the mail8.ntf template does have it enabled. You may choose to disable this property in the template prior to creating new mail files or converting existing mail files to version 8.
As with enabling ODS48, a copy-style compact is required to enable design compression. If you are planning on upgrading to ODS48 and enabling Design Compression on mail files, you should consider doing these at the same time by enabling the Design Compression property prior to running the compact so that you don't have to run the copy-style compact twice.
In planning your Domino 8 upgrade, the considerations above regarding the new ODS should assist you in deciding whether or not you will wish to enable ODS48.