¶ 1 Leave a comment on paragraph 1 0 It may be preferable for repository staff to be the first to preview and capture disk media, using write protection technologies that protect the original media from inadvertent change. In doing so, it is good practice to create hash values (sometimes known as checksums), which serve as unique “digital fingerprints” for each and every digital object or file. (If a single bit is changed in a file, a different hash value will be produced by the altered file; conversely, if in 100 years’ time a file is subjected to the same test and it yields the same hash value as when it was first received, a repository can be confident that the file has remained unchanged over the century.)
¶ 2 Leave a comment on paragraph 2 0 In some cases, donors and dealers may want to undertake this task themselves, perhaps with the assistance of a technical specialist. If so, hash information can help staff verify that the files arriving at a repository match those transferred by the donor. Comparing and confirming hash values generated prior to transfer with those generated once the materials have arrived on-site requires a certain level of technical comfort and expertise on the part of both the donor and the receiving repository. Mismatched hash values would indicate that the materials that arrived at the repository had been altered or corrupted in transit. Staff would need to determine whether to accept these damaged files, decline them, or work with the donor to determine the source of the problem and, if possible, fix it.
¶ 3 Leave a comment on paragraph 3 0 If internal policies and donor agreements allow, repository staff will create disk images of media (to capture an exact copy of the entire contents of a disk, for example) or working copies of individual files and use available tools to preview the contents shortly after the materials arrive on-site. (Sometimes an archival repository may offer or prefer to undertake a preview or even an actual capture at the site of the donor or dealer.) If a repository determines that the content of the transferred media or set of files does not match the original inventory or fit the repository’s collection development policy, further discussion with the donor or dealer may be in order.