Unearthing the Impact of Sanitize on Performance and Latency in embedded storage

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Publish Date: 
Wednesday, September 29, 2021
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It is broadly known that in an operating system, if any file is deleted, Discard will be issued to underlying storage device. When user deletes file through Operating system, it is not physically deleted from the storage medium, as a matter of fact, this file data is marked as Invalid but remains in the unmapped address space. In another instance, when host performs over write on the previously written logical space and then this previously written memory space can be invalidated by discard operation. These all cases may create lot of fragmentation in device and eventually make the system slow i.e. user starting seeing lag in application, performance drop, high write latency etc. In order to handle this unmapped address space effectively there is provision in JEDEC specification and that is called “Sanitize”. In a nutshell, sanitize process removes the data from the unmapped address space either by performing Physical erase of all the blocks or vendor defined method. To unearth the impact of sanitize, various real time work load taken from different automotive host patterns and examined along with FTL data extracted using debugging Firmware. This study helps to understand how seasonably use of sanitize helps in reduce the latency, better user experience with applications and improve the performance etc. Sanitize utilized in accordance with storage device policy will significantly improve QoS (Quality of Service) i.e. better consistency and predictability of latency (storage response time) and performance while serving read/write commands.

  • How sanitize process helps in improving user experience.
  • Performance and latency improvement
  • Benefit of adding Discard in mount options
  • Impact of unmapped user space in real world scenario
  • Impact on the Lifetime of the device when sanitize is done regularly

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