Titan Disk Storage Charging

Combining the OS/390 North and South Systems into a single system (i.e., Titan) is complicated because North and South used different methods of charging for disk data storage services. CIT has now determined how to make the transition from North rates to new Titan rates with minimal impact on customers’ bills. After a transition period, all Titan disk storage will be charged at $.01/MB-day.

This article supersedes any previous discussions and documentation of disk data rates.

Before describing the new billing approach, it’s useful to review how the North and South charges were/are computed.

North System

On the old North System (and initially on Titan), disk data was charged at the rate of $.045/MB-day. Once the data became inactive for a period of several weeks, it was moved to inactive storage. Any time the data was used, it was brought back to disk and again charged at $.045/MB-day. The data flow and charges are illustrated in Figure 1.

Figure 1: A flow chart of the data flow and charges for the old North System. It shows that Active Disk Data is charged at the rate of $.045/MB/day, that the rate for inactive data storage is $.00 and that any data the remains unused for over 24 months is removed.

Figure 1: North

South System

Disk data on the South System is handled similarly, except that the management software “intelligently” moves data to secondary storage based on data set size, characteristics, and activity rather than just using time since last access. The charge for data on the South System is $ .011 MB-day regardless of the media used for storage. Pictorially the data flow and charges are shown in Figure 2.

Figure 2: This image shows the data flow and charges for the South System. It shows that Primary Storage for data on South is charged at $.011, as is any data stored in Secondary Storage. It also shows that data in Secondary Storage can be deleted by the owner.

Figure 2: South

Titan Disk Data Charging

We have selected the South System storage management software and charging method, although at the lower rate of $.01/MB-day regardless of location. CIT will move to this charging scheme in a way that minimizes the effect on customers’ data storage costs.

Currently there is a great deal of inactive data (from the former North System and early Titan use) that is being stored at no charge. This data will go away over the next two years either because its lifetime expires or because it is used and then transferred to secondary storage by the new Titan management software. As data moves into the new data management system, it will incur a charge regardless of location. To keep overall storage charges stable, we will gradually reduce the price of primary storage as the amount of secondary storage in use increases. Please be aware that, because the charging methods are so different, effective cost management of storage may require different strategies. Call TASC at (301) 594-6248 if you would like to discuss efficient management techniques for your data storage.

Transition Charging

On June 13 the Titan system began using the data management software currently in use on the South System. This product manages all new, changed, or referenced (i.e., read) data on the Titan system. The inactive data that was originally managed by the old system will remain available to Titan customers until it is either deleted after 24 months of inactivity or is used and brought back to be managed by the new system. There will be no charge for the storage of this old inactive data while it remains under the management of the old system.

Prior to July 1, 2002, charging for disk data on Titan was the same as the former North System (see Figure 1). Since July 1 when data is created by a former North System user or is recalled from the old system, it is initially placed on the primary disks and charged at the rate of $.04/MB-day (slightly lower than previously). When it is moved to secondary storage, the rate drops to $.01/MB-day. Pictorially, this is illustrated in Figure 3.

* Will also be deleted per management class specification—see the Titan User’s Guide,

“Titan Management Classes” (section 10.1.4).

Figure 3: Titan

As the “free” inactive data is gradually removed from the old data management system into the new system, CIT will begin lowering the cost of primary storage so that customer rates will not increase. We anticipate that this will be done by dropping the primary storage charge by $.005/MB-day increments until it reaches $.01/MB-day. At that time the rate will be slightly lower than the current South System.