Split database backup file using PowerShell and merge it back - windows

Question

I am new to PowerShell having some issues with getting corrupted files when splitting and re attaching files back together using PowerShell.
I have a remote server from which I need to download a .bak file with the size of 44GB. To be able to do this I am splitting the files in to smaller (100mb) pieces using this script.
$from = "D:\largebakfile\largefile.bak"
$rootName = "D:\foldertoplacelargebakfile\part"
$ext = "PART_"
$upperBound = 100MB
$fromFile = [io.file]::OpenRead($from)
$buff = new-object byte[] $upperBound
$count = $idx = 0
try {
do {
"Reading $upperBound"
$count = $fromFile.Read($buff, 0, $buff.Length)
if ($count -gt 0) {
$to = "{0}{1}{2}" -f ($rootName, $idx, $ext)
$toFile = [io.file]::OpenWrite($to)
try {
"Writing $count to $to"
$tofile.Write($buff, 0, $count)
} finally {
$tofile.Close()
}
}
$idx ++
} while ($count -gt 0)
}
finally {
$fromFile.Close()
}
After this is done and the "PART_" files are downloaded to local computer I use this script to merge the files back together to 1 .bak file.
# replace with the location of the "PARTS" file
Set-Location "C:\Folderwithsplitfiles\Parts"
# replace with the SQL backup folder in your computer.
$outFile = "C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\Backup\newname.bak"
#The prefix for all PARTS files
$infilePrefix ="C:\Folderwithsplitfiles\Parts\PART_"
$ostream = [System.Io.File]::OpenWrite($outFile)
$chunkNum = 1
$infileName = "$infilePrefix$chunkNum"
$offset = 0
while(Test-Path $infileName) {
$bytes = [System.IO.File]::ReadAllBytes($infileName)
$ostream.Write($bytes, 0, $bytes.Count)
Write-Host "read $infileName"
$chunkNum += 1
$infileName = "$infilePrefix$chunkNum"
}
$ostream.close();
#Get-FileHash $outfile | Format-List
When trying to restore database in SSMS I get an error basically saying that the file is corrupted and can't be restored.
I have been struggling with this a couple of days now and don't seem to get my head correct.
Everything seems like its working but something is causing me these errors. Does anyone have any ideas?

Answer 1

Might I suggest you look at Background Intelligent Transfer Service, you should be able to download the whole file in one piece to save over complicating anything. (Also supports starting/stopping the transfer etc.)