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--- windows_wiki:powershell_-_write_zeroes_to_drive [2016/06/13 15:24]
vitrek [Write Zeroes to Drive]
+++ windows_wiki:powershell_-_write_zeroes_to_drive [2019/05/25 23:50]
@@ Line 1: / Line 1: @@
-====== Powershell - Write Zeroes To Drive ======
-**General Information**
-This script is intended for usage when you have a clustered or shared volume that is connected to a san that is reporting full even though Windows has data free on the drive.
-This behavior is due to windows not wiping freespace on the drive. Most san's do not understand free space if the space does not contain only 0's
-====== Write Zeroes to Drive ======
-Section 1 content.
-<file>
-<#
-.SYNOPSIS
- Writes a large file full of zeroes to a volume in order to allow a storage
- appliance to reclaim unused space.
-.DESCRIPTION
- Creates a file called ThinSAN.tmp on the specified volume that fills the
- volume up to leave only the percent free value (default is 5%) with zeroes.
- This allows a storage appliance that is thin provisioned to mark that drive
- space as unused and reclaim the space on the physical disks.
-.PARAMETER Root
- The folder to create the zeroed out file in.  This can be a drive root (c:\)
- or a mounted folder (m:\mounteddisk).  This must be the root of the mounted
- volume, it cannot be an arbitrary folder within a volume.
-.PARAMETER PercentFree
- A float representing the percentage of total volume space to leave free.  The
- default is .05 (5%)
-.EXAMPLE
- PS> Write-ZeroesToFreeSpace -Root "c:\"
- This will create a file of all zeroes called c:\ThinSAN.tmp that will fill the
- c drive up to 95% of its capacity.
-.EXAMPLE
- PS> Write-ZeroesToFreeSpace -Root "c:\MountPoints\Volume1" -PercentFree .1
- This will create a file of all zeroes called
- c:\MountPoints\Volume1\ThinSAN.tmp that will fill up the volume that is
- mounted to c:\MountPoints\Volume1 to 90% of its capacity.
-.EXAMPLE
- PS> Get-WmiObject Win32_Volume -filter "drivetype=3" | Write-ZeroesToFreeSpace
- This will get a list of all local disks (type=3) and fill each one up to 95%
- of their capacity with zeroes.
-.NOTES
- You must be running as a user that has permissions to write to the root of the
- volume you are running this script against. This requires elevated privileges
- using the default Windows permissions on the C drive.
-#>
-param(
-  [Parameter(Mandatory=$true,ValueFromPipelineByPropertyName=$true)]
-  [ValidateNotNullOrEmpty()]
-  [Alias("Name")]
-  $Root,
-  [Parameter(Mandatory=$false)]
-  [ValidateRange(0,1)]
-  $PercentFree =.05
-)
-process{
-  #Convert the $Root value to a valid WMI filter string
-  $FixedRoot = ($Root.Trim("\") -replace "\\","\\") + "\\"
-  $FileName = "ThinSAN.tmp"
-  $FilePath = Join-Path $Root $FileName
-  #Check and make sure the file doesn't already exist so we don't clobber someone's data
-  if( (Test-Path $FilePath) ) {
-    Write-Error -Message "The file $FilePath already exists, please delete the file and try again"
-  } else {
-    #Get a reference to the volume so we can calculate the desired file size later
-    $Volume = gwmi win32_volume -filter "name='$FixedRoot'"
-    if($Volume) {
-      #I have not tested for the optimum IO size ($ArraySize), 64kb is what sdelete.exe uses
-      $ArraySize = 64kb
-      #Calculate the amount of space to leave on the disk
-      $SpaceToLeave = $Volume.Capacity * $PercentFree
-      #Calculate the file size needed to leave the desired amount of space
-      $FileSize = $Volume.FreeSpace - $SpacetoLeave
-      #Create an array of zeroes to write to disk
-      $ZeroArray = new-object byte[]($ArraySize)
-      #Open a file stream to our file
-      $Stream = [io.File]::OpenWrite($FilePath)
-      #Start a try/finally block so we don't leak file handles if any exceptions occur
-      try {
-        #Keep track of how much data we've written to the file
-        $CurFileSize = 0
-        while($CurFileSize -lt $FileSize) {
-          #Write the entire zero array buffer out to the file stream
-          $Stream.Write($ZeroArray,0, $ZeroArray.Length)
-          #Increment our file size by the amount of data written to disk
-          $CurFileSize += $ZeroArray.Length
-        }
-      } finally {
-        #always close our file stream, even if an exception occurred
-        if($Stream) {
-          $Stream.Close()
-        }
-        #always delete the file if we created it, even if an exception occurred
-        if( (Test-Path $FilePath) ) {
-          del $FilePath
-        }
-      }
-    } else {
-      Write-Error "Unable to locate a volume mounted at $Root"
-    }
-  }
-}
-</file>
-See https://www.dokuwiki.org/wiki:syntax#syntax_highlighting for supported syntax highlighting.