Windows Vista Forums

LastWriteTime and Locating the drive letter of a flash drive.

  1. #1


    Fred J. Guest

    LastWriteTime and Locating the drive letter of a flash drive.

    Part 1
    Is the Get-ChildItem property 'lastwritetime' equivalent to explorer's
    'Date Modified'?
    Part 2
    I am running Windows XP. I back up my files to a flash drive. My
    current 'cmd' script blindly erases the files from my flash drive and
    then 'copies' my working set from my hard drive to the flash drive.

    I am writing a PS script that compares the 'lastwritetime' date
    between the two media. Interesting enough I have stumbled upon this;
    The lastwritetime as it appears on the flash drive is usually 1 to 2
    seconds later than the lastwritetime on the hard drive. As I
    understand it, these are not the physical times that the files were
    copied, but rather when they were modified. So I am wondering why
    this inconsistency occurs?

    To accommodate this I do something like;

    if ($timediff.totalseconds -le 60)
    {write-Host "dont copy file $hdFilePath"
    $CurrentFileCount++
    }
    else {
    write-Host "copy required for $hdFilePath"
    copy-Item $hdFilePath -destination $fdDir
    if ($?) {
    write-Host "Copy ok for $hdfilepath to $fdDir"
    $UpdateCount++
    }else {
    read-Host -prompt "FAILURE on Copy of $hdfilepath to
    $fdDir"}
    }

    Part 3
    Depending on the current state of chaos, my flash-drive's drive letter
    may change. So I try to dope out the drive letter of the flash drive
    by doing something like;
    get-psdrive | foreach-object {if($_.description -like "lexar")
    {$flashdrive= $_.name}}

    Are there other alternatives and what property suggests that the flash
    drive is 'Removable Storage' as described in 'My Computer?

    Thank you,
    Fred J.


      My System SpecsSystem Spec

  2.   


  3. #2


    Kiron Guest

    Re: LastWriteTime and Locating the drive letter of a flash drive.

    Part 1
    LastWriteTime is equivalent to Date Modified

    Part 2
    Maybe this KB support article helps
    http://support.microsoft.com/kb/299648

    Part 3
    To get the type of drive use System.IO.DriveInfo.GetDrives Method:

    [io.driveinfo]::getDrives() | format-table Name, DriveType -auto

    To get all removable drives:

    [io.driveinfo]::getDrives() | where-object {$_.DriveType -eq 'Removable'} |
    select-object Name

    http://msdn2.microsoft.com/library/S...GetDrives.aspx
    http://msdn2.microsoft.com/en-us/lib...drivetype.aspx
    http://msdn2.microsoft.com/en-us/lib...drivetype.aspx

    --
    Kiron


      My System SpecsSystem Spec

  4. #3


    gelyon@gmail.com Guest

    Re: LastWriteTime and Locating the drive letter of a flash drive.

    Part 2:
    FAT32 timestamp resolution = 2 seconds.
    NTFS timestamp resolution = 100 nanoseconds.



      My System SpecsSystem Spec

  5. #4


    Fred J. Guest

    Re: LastWriteTime and Locating the drive letter of a flash drive.

    On Jul 11, 3:41 pm, "Kiron" <K...@HighPlainsDrifter.com> wrote:
    > Part 1
    > LastWriteTime is equivalent to Date Modified
    >
    > Part 2
    > Maybe this KB support article helpshttp://support.microsoft.com/kb/299648
    >
    > Part 3
    > To get the type of drive use System.IO.DriveInfo.GetDrives Method:
    >
    > [io.driveinfo]::getDrives() | format-table Name, DriveType -auto
    >
    > To get all removable drives:
    >
    > [io.driveinfo]::getDrives() | where-object {$_.DriveType -eq 'Removable'} |
    > select-object Name
    >
    > http://msdn2.microsoft.com/library/S...drivetype.aspx
    >
    > --
    > Kiron


    Thank you,
    Fred Jacobowitz


      My System SpecsSystem Spec

  6. #5


    Fred J. Guest

    Re: LastWriteTime and Locating the drive letter of a flash drive.

    On Jul 11, 6:47 pm, gel...@gmail.com wrote:
    > Part 2:
    > FAT32 timestamp resolution = 2 seconds.
    > NTFS timestamp resolution = 100 nanoseconds.


    Thank you. I don't understand why the time resolution on a copy file
    should be skewed (I can understand lastwritetime when a file is
    modified) but it does appear to be.
    Fred J


      My System SpecsSystem Spec


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