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RAID Archive

The currently available options for archival storage are:

  • Nearline RAID arrays
  • Tape nearline and offline libraries
  • Optical nearline and offline libraries

Nearline RAID arrays are basically cheaper versions of the primary RAID array. They are usually created with lower cost magnetic disk drives with larger individual capacities. Like the primary RAID array these will need to be regularly backed up as part of the organisations disaster recovery procedures. Nearline RAID arrays meet the archive requirements as follows:

  1. Lower cost than existing primary storage
    • Lower acquisition cost, due to lower reliability drives
    • Operational costs will be similar to primary storage, in terms of
    • High energy consumption and cooling
    • Energy reduction by powering down drives (MAID=Massive Array of Idle Disks)
    • Backup procedures
    • Monitoring and replacement of failed drives
  2. Long term retention
    • Not possible
    • Entire RAID array would need to be replaced and the data migrated to new system every 2-5 years.
  3. Compliance with regulations
    • Complicated software algorithms provide WORM type behaviour
  4. Transparent access to archival information
    • Yes, provide a link between existing primary RAID and archive
  5. Offline management of very old information
    • Not possible
    • Magnetic hard disks can’t be safely removed and stored long term outside of the archive

Nearline RAID arrays are best suited to short term archives, less than 5 years, where the data is not vital and there is sufficient capacity in the existing data backup process to include this data. Continuous power consumption and the lack of removability of the media make RAID technology less suited as long-term archiving technology.