How to calculate TBW and DWPD of SSDs?

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How to calculate TBW and DWPD of SSDs?

TBW (Total Bytes Written) - indicates how much data can be written to the drive during the warranty period for the drive to hold its parameters. This is a value calculated based on the DWPD parameter. Very often in the case of SSDs, the manufacturer provides the warranty period or TBW.

How to calculate TBW knowing the DWPD parameter of the drive:

Pattern:

  • DWPD (Drive Writes Per Day) x disk capacity x 365 days (1 year) x (length of warranty)

Example drive:

Calculations:

  • 5DWPD x 1920GB x 365 x 5 = 17.52 PBW (TBW in PB)

DWPD (Drive Writes Per Day) - indicates the number of information that can be written each day to not reach the TBW limit before the end of the warranty.

Method 1

Pattern:

  • disk capacity TB x 1000 / 365 days x how many years x disk capacity GB

Example drive:

Calculations:

  • DWPD = 16700 x 1000 / 365 x 5 x 1920GB
  • 17520000 / 3504000
  • DWPD = 5

Method 2

Pattern:

  • DWPD = TBW dysku w GB / okres gwarancji w dniach

Example drive:

Calculations:

  • 17520000 / 1825 = 9600GB dziennie = 9600 / 1920 = 5 DWPD

Summary

For business applications, TBW and DWPD metrics are important when choosing SSDs:

  • For read-only or OS-only disks, the DWPD parameter can be ~1 DWPD.
  • For disks where writing is done frequently 75:25% (Write:Read), this parameter should be at least 3DWPD.
  • For applications where writing takes place all the time and data is continuously overwritten, this parameter should be at least 10DWPD

The above values are only illustrative and the determination of the required DWPD or TBW parameter should be based on real demand.

Currently, you can find Enterprise drives on the market:

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