Contact Information

IT Service Desk

Data Removal Service

for Staff

Data stored inside a computer device must be removed properly and securely when the device needs to be transferred or disposed of.  The Computing Services Centre (CSC) provides the following three options to colleagues for clearing the data in Hard Disk Drive (HDD), Solid-State Disk (SSD), USB thumb drive, memory card and smart phone:

  1. Wiping/Clearing/Purging
    Data are cleared by connecting the HDD/SSD to a wiper machine and overwriting random values to the disk multiple times.  Since this method does not cause destructive damage to the disk, the disk can be reused.
  2. Degaussing 
    A degausser is used to disrupt the magnetic fields in the HDD.  After degaussing, the data will be removed and the HDD will no longer be recoverable and reusable.  The degausser has its limitation as it is only effective on magnetic type devices, while storage devices such as SSD, which use electric charge to store data on individual transistors, cannot be destroyed by the degausser.
  3. Shredding 
    A shredder is used to physically crush and grind a device into small fragments.  This option works on most storage devices such as HDD, SSD, USB drive, memory card, mobile phone, etc.  To avoid causing any damage to the shredder, plastic parts and sticky labels must be removed before putting the device into the shredder and this operation must be carried out by trained CSC personnel.


  Wiping Degaussing Shredding
Device reusable Yes No No
Remove data in HDD Yes* Yes Yes
Remove data in SSD Yes* No Yes
Destroy data on CD/DVD/memory card/USB thumb drive/mobile phone N/A N/A Yes
Time to take  A few hours <10 sec <10 sec

*  Device needs to be in working condition

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