The International Council on Archives (ICA) has developed a number of standards on archival description including the General International Standard Archival Description ISAD(G).  ISAD(G) is meant to be used in conjunction with national standards or as a basis for nations to build their own standards.  In the United States, ISAD(G) is implemented through Describing Archives: A Content Standard , popularly known as "DACS".  In Canada, ISAD(G) is implemented through the Council of Archives  as the Rules for Archival Description , also known as "RAD". 
Some RAID levels (such as RAID 5 and RAID 1) can only sustain a single drive failure, although some RAID 1 implementations consist of multiple mirrors, and can therefore sustain multiple failures. The problem is that the RAID array and the data it contains are left in a vulnerable state until a failed drive is replaced and the new disk is populated with data. Because drives have much greater capacity now than when RAID was first implemented, it takes a lot longer to rebuild failed drives. Longer rebuild times increase the chance that a second drive will fail before the first drive is rebuilt.