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WEC7 - TexFAT - How to verify USB Flash Drive supports Atomic Sector Writes? RRS feed

  • Question

  • Hi,

    From the statement in Windows Compact Documentation (see picture below and link) seems like:

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    • The Flash Driver provided in WEC7 supports Atomic Sector Writes.
    • That most Flash hardware (I'm using USB flash Drive - SanDisk 3.0 #SCDZ43) provide atomic sector writes.

    My Specific Questions:

       1.)  Does WEC7's flash driver provide Atomic Sector Writes?

       2.)  How can I determine if my USB flash drive supports Atomic Sector Writes? (spec sheet, test with scope?)

    Thank you again so much!

    WillieJoe

    Microsoft Documentation about TexFAT and Atomic Sector Writes

    Wednesday, December 14, 2016 6:52 PM

Answers

  • Hi Willie Joe,

    You already have the answer to 1 as yes but the answer to 2 is something for the drive manufacturer. Specifically:

    "Some hard disk drives report the physical sector size of the disk incorrectly. For example, the drive is released a "4K" drive without reporting that it is indeed a 4K drive. Applications use the reported physical sector size as a notion of atomicity and perform I/O based on this. The most basic example is a database-style application will only store one commit record within the unit of atomic write for fear of loss if power is lost or if a physical sector becomes physically bad. When the reported physical sector size is not the unit of atomicity, serious reliability concerns can arise in scenarios where power is lost such as: Applications can fail to recover, and users will need to restore from backup. Applications can fail to recover, but the application will need to perform a lengthy consistency check. Corruption of metadata, log file data, user data, or even data from other applications." (From https://msdn.microsoft.com/en-us/windows/hardware/commercialize/design/compatibility/device-storage )

    Sincerely,

    IoTGirl

    • Marked as answer by WillieJoe2 Thursday, January 5, 2017 7:31 PM
    Friday, December 23, 2016 4:20 AM
    Moderator

All replies

  • Hi Willie Joe,

    You already have the answer to 1 as yes but the answer to 2 is something for the drive manufacturer. Specifically:

    "Some hard disk drives report the physical sector size of the disk incorrectly. For example, the drive is released a "4K" drive without reporting that it is indeed a 4K drive. Applications use the reported physical sector size as a notion of atomicity and perform I/O based on this. The most basic example is a database-style application will only store one commit record within the unit of atomic write for fear of loss if power is lost or if a physical sector becomes physically bad. When the reported physical sector size is not the unit of atomicity, serious reliability concerns can arise in scenarios where power is lost such as: Applications can fail to recover, and users will need to restore from backup. Applications can fail to recover, but the application will need to perform a lengthy consistency check. Corruption of metadata, log file data, user data, or even data from other applications." (From https://msdn.microsoft.com/en-us/windows/hardware/commercialize/design/compatibility/device-storage )

    Sincerely,

    IoTGirl

    • Marked as answer by WillieJoe2 Thursday, January 5, 2017 7:31 PM
    Friday, December 23, 2016 4:20 AM
    Moderator
  • Thanks for the confirmation, WillieJoe2!
    Thursday, January 5, 2017 9:19 PM
    Moderator