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This is an old revision of the document!

HDD

  • LMR - Longitudal Magnetic Recording
  • CMR/PMR - Conventional Magnetic Recording / Perpendicular Magnetic Recording
    • Tech from 2000. Normal tracks but vertical orientation. 3x density gain
  • SMR - Shingled Magnetic Recording (overlapping tracks)
    • Trick to buffers write. Some small SSD memory, some space on platers are used for “journal” with fast CMR access, then disk is using idle time to rewrite it into SMR area. This can be very problematic during huge write load - e.g. RAID rebuild. So keep 20% of disc empty.

Examples

  • Seagate
    • Barracudy should be SMR
    • IronWOlf still CMR
  • Toshiba
    • 1 to 6TB - SMR
    • X300, P300, N300 - CMR
    • TOSHIBA HDWD120 - PMR
  • WD
  • WD Red 3,5“ (WD20EFAX, WD30EFAX, WD40EFAX, WD60EFAX)- SMR
  • WD Blue 3,5” (WD20EZAZ, WD60EZAZ) - SMR
  • WD Blue 2.5“ (WD10SPZX, WD20SPZX) - SMR
  • WD Black 2,5” (WD10SPSX) - SMR

SSD