When dealing with a 350GB fulltext index containing hundreds of thousands of small files, traditional backup methods that require stopping services become impractical. The downtime window grows unacceptably long, and consistency becomes a major concern when files are constantly being modified.

VSS works by creating point-in-time snapshots of volumes while maintaining file system consistency. The key components relevant to our scenario:

Writer: The indexer application (if VSS-aware)
Requester: CommVault Galaxy 7.0 backup software
Provider: Microsoft Software Shadow Copy Provider
Storage: Separate volume for shadow copy storage

For our specific environment (Windows Server 2003 SP2):

1. Configure VSS through Computer Management → Disk Management
2. Select the source volume → Properties → Shadow Copies
3. Set the storage volume (must be different from source)
4. Configure schedule for daily snapshots
5. Set appropriate storage size (minimum 350GB + overhead)

There are multiple ways to access the shadow copies programmatically:

Method 1: Using VSSADMIN Command Line

vssadmin list shadows 
vssadmin create shadow /For=C:

Method 2: VBScript Automation

Set objWMIService = GetObject("winmgmts:\\.\root\cimv2")
Set objShadow = objWMIService.Get("Win32_ShadowCopy")
errResult = objShadow.Create("C:\", "ClientAccessible", strShadowID)

Method 3: PowerShell Alternative

$shadow = (gwmi -list win32_shadowcopy).Create("C:\", "ClientAccessible")
$shadowID = $shadow.ShadowID
$shadowPath = (gwmi win32_shadowcopy | ? {$_.ID -eq $shadowID}).DeviceObject

To make CommVault work with VSS snapshots:

1. Enable "Use Volume Shadow Copy" in backup job properties
2. Configure pre/post commands if special handling needed
3. Set appropriate timeout values for large volumes

For optimal performance with large I/O-heavy volumes:

• Place shadow storage on fast disks (preferably separate array)
• Monitor performance during first few backup cycles
• Consider differential backup strategies between full VSS backups

Some potential problems and solutions:

Insufficient storage space: 
   vssadmin resize shadowstorage /For=C: /On=D: /MaxSize=400GB

Writer timeouts:
   vssadmin list writers
   Check application logs for VSS errors

Backup failures:
   vssadmin list shadows /all
   Verify shadow copies are actually being created

When dealing with large, I/O-intensive volumes - particularly those containing filesystem-based fulltext indexes with hundreds of thousands of small files - traditional backup approaches present significant challenges. Stopping the indexer service for hours during backup operations creates unacceptable downtime, especially when dealing with 350GB+ volumes where backup windows can stretch painfully long.

Windows Volume Shadow Copy Service (VSS) provides the perfect solution by creating point-in-time snapshots that:

• Maintain file consistency without service interruption
• Allow backup operations to run against the snapshot instead of live files
• Eliminate the need for lengthy service outages

Here's how to properly configure VSS for your scenario on Windows Server 2003 SP2:

@echo off
:: Configure VSS settings
vssadmin add shadowstorage /for=C: /on=D: /maxsize=10%
vssadmin create shadow /for=C:

:: Map the shadow copy to a drive letter
setlocal
for /f "tokens=2 delims= " %%A in ('vssadmin list shadows ^| find "Shadow Copy Volume"') do (
    set SHADOW_DEVICE=%%A
)
subst X: %SHADOW_DEVICE%
endlocal

To make your CommVault Galaxy 7.0 backups work with VSS snapshots:

1. Create a pre-backup script that creates the shadow copy
2. Configure your backup job to target the shadow copy drive letter
3. Add a post-backup script to remove the temporary drive mapping

For more robust automation, here's a VBScript solution:

Set objShell = CreateObject("WScript.Shell")
Set objFSO = CreateObject("Scripting.FileSystemObject")

' Create shadow copy
strCommand = "vssadmin create shadow /for=C:"
intReturn = objShell.Run(strCommand, 0, True)

If intReturn <> 0 Then
    WScript.Echo "Error creating shadow copy"
    WScript.Quit 1
End If

' Get shadow copy device path
Set objExec = objShell.Exec("vssadmin list shadows")
strOutput = objExec.StdOut.ReadAll

arrLines = Split(strOutput, vbCrLf)
For Each strLine in arrLines
    If InStr(strLine, "Shadow Copy Volume:") > 0 Then
        strShadowDevice = Trim(Split(strLine, ":")(1))
        Exit For
    End If
Next

' Map drive letter
objShell.Run "subst X: " & strShadowDevice, 0, True

• Schedule snapshots during periods of relatively low I/O activity
• Monitor shadow storage allocation to prevent volume exhaustion
• Test restore procedures regularly to ensure snapshot integrity
• Consider implementing PowerShell scripts for more modern environments

If you encounter problems:

1. Check available storage space in your shadow copy storage area
2. Verify the Volume Shadow Copy service is running
3. Ensure proper permissions for the account running the backup
4. Review event logs for VSS-related errors