Several libraries with collections of 175,000 to 250,000 titles have installed DataPhase automated circulation systems configured with two 192MB (mega-byte) Data -General -disk drives. In each case, the libraries were assured that two 192MB drives would be sufficient to accommodate the bibliographic records, associated indices and patron files. Many of these libraries have now run out of disk storage space even though they have loaded fewer than 175,000 records.
In the case of one of the affected libraries, an independent consultant hired by the library had argued strongly for 300MB drives. The vendor, however, had assured the library that the smaller drives were sufficient and that use of the larger drives might result in hardware maintenance problems since the larger drives would be Control Data drives, units which Data General, the manufacturer of the rest of the equipment, will not maintain. A local third-party maintenance firm would, therefore, have had to have been retained.
It has been pointed out that some of the libraries contributed to the problem of insufficient storage by entering longer records than those that they had specified in their Requests for Proposal. However, even after adjusting for the effect of the longer records, it appears that the vendor did seriously underestimate the amount of overhead its system required.
Libraries with collections in the 175-250,000 title range should require disk drives of no less than 300MB. This applies not only in the case of systems supplied by DataPhase, but also to systems supplied by other vendors as well.
Unfortunately, the vendors have not provided libraries with sufficient information to determine the amount of disk storage that is needed. Experience suggests that a library can ensure adequate capacity by multiplying the number of titles held by 3,000 to arrive at the amount of disk storage for a system which supports full-MARC records, authority control, and disk to disk backup. This usually provides for five years of expansion for a library that increases its collection by 5% per year. Using this calculation a library with 175,000 titles would need 525MB of storage or two 300MB drives.
Libraries which do not plan to load full-MARC records should use a multiplier of 1,800 for up to 400 characters per record.