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Both old and new data formats co-exist at the same time
Penrose allows you to perform Lazy migration. Lazy migrations work on a simple assumption. You constantly have two views of your data: the old data format view and the new data format view. Your directory will start off with only old entries. Entries are then slowly migrated over to the new format over the course of time - this can be days, weeks or even a month or two. During all this time, you will have a mix of entries in the old and new data formats. In the end, you will end up with all entries in the new data format. At all times however, you can access data using both views.
This has several large advantages. First of all, you don't need to carry out a "brute-force everything at once" reconfiguration of all applications. Start migrating one, or just a few applications. These applications, once you flip the switch, will be able to see all entries in the new data format and can "hit the ground running" at once.
Also, Penrose eliminate virtually all downtime. The "switch-over" to start migrating typically takes just a few seconds. This avoids any stress in trying to keep migrations within a defined time-window. Even if you have a very large amount of data to migrate, there is almost no down time. Furthermore, Penrose can eliminate the need to negotiate extra large maintenance windows, just in order to make sure there was enough time to convert data.
NIS to LDAP Migration
