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LastWriteTime and Locating the drive letter of a flash drive.

F

Fred J.

#1
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 Computer

K

Kiron

#2
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/System.IO.DriveInfo.GetDrives.aspx
http://msdn2.microsoft.com/en-us/library/system.io.driveinfo.drivetype.aspx
http://msdn2.microsoft.com/en-us/library/system.io.drivetype.aspx

--
Kiron
 

My Computer

F

Fred J.

#4
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/...ft.com/en-us/library/system.io.drivetype.aspx
>
> --
> Kiron


Thank you,
Fred Jacobowitz
 

My Computer

F

Fred J.

#5
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 Computer

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