The Upside<\/h2>\n

RAID 5 offers very good performance and decent data safety:<\/p>\n

\n
• RAID 5 will continue to function after a single drive failure<\/li>\n
• It’s fast, though slower than RAID 0 because parity data must be written<\/li>\n
• Total array capacity is greater than with RAID 1 mirroring, though you lose the equivalent of one drive’s capacity. (16TB + 16TB + 16TB = 32TB)<\/li>\n
• Each new disk increases the number of available data lines. The resulting broader, multi-lane pipe increases sustained read and write speeds but yields slightly slower random access times<\/li>\n<\/ul>\n

  RAID 5’s throughput performance only increases to the limit of the the bus technology involved. Multiply the maximum speed of your media and divide by the maximum bus bandwidth to determine how many disks this will take. Beyond that, additional disks only increase capacity.<\/p>\n

  The Downside<\/h2>\n

  RAID 5 is safer than RAID 0, but it’s not fail-safe:<\/p>\n

  \n
  • The array fails if a subsequent drive failure occurs before the first failed drive is replaced and the array is rebuilt<\/li>\n
  • Performance will drop while the array is being rebuilt<\/li>\n<\/ul>\n

    A second drive failure occurring before a completed array rebuild is rare, but not unheard of–the strain of the rebuild can tax remaining drives. If you’re truly worried about the data, RAID 6 with its ability to withstand two drive failures offers a far better statistical margin of error.<\/p>\n

    When to Use RAID 5<\/h2>\n

    Use RAID 5 when speed and capacity are paramount, but you still want a margin of safety. To maximize protection, when a drive fails, initiate a backup immediately and replace the failed drive with the utmost alacrity.<\/p>\n

    RAID 5E, or enhanced RAID 5, means that a “hot spare”, i.e., an extra disk is included in the array so that rebuilding can begin immediately without physical intervention.<\/p>\n