From http://blogs.technet.com/b/diegoviso/archive/2015/12/11/migrating-asm-to-arm.aspx

MigrateASMtoARM.ps1

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# Connect to an Azure subscription
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Login-AzureRmAccount

# Select your subscription if required
Select-AzureRmSubscription -SubscriptionId "yoursubscriptionid"

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# Copy a Vhd from an existing storage account to a new storage account
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# Source VHD
$srcVhd = "https://sourcesa.blob.core.windows.net/vhds/sourcevhd.vhd"

# Destination VHD name
$destVhdName = "destvhd.vhd"

# Destination Container Name 
$destContainerName = "vhds"

# Source Storage Account and Key
$srcStorageAccount = "sourcesa"
$srcStorageKey = "sourcesakey"

# Target Storage Account and Key
$destStorageAccount = "destsa"
$destStorageKey = "destsakey"

# Create the source storage account context (this creates the context, it does not actually create a new storage account)
$srcContext = New-AzureStorageContext -StorageAccountName $srcStorageAccount -StorageAccountKey $srcStorageKey

# Create the destination storage account context 
$destContext = New-AzureStorageContext -StorageAccountName $destStorageAccount -StorageAccountKey $destStorageKey

# Start the copy  
$blob1 = Start-AzureStorageBlobCopy -Context $srcContext -AbsoluteUri $srcVhd -DestContainer $destContainerName -DestBlob $destVhdName -DestContext $destContext -Verbose 

# check status of copy
$blob1 | Get-AzureStorageBlobCopyState

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# Create a Virtual Machine from an existing OS disk
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$resourceGroupName= "dest-rg"
$location= "SouthEastAsia"
$storageAccountName= "destsa"
$vmName= "destvm"
$vmSize="Standard_A1"
$vnetName= "dest-vnet"

# Get storage account configuration for the target storage account
$StorageAccount = Get-AzureRmStorageAccount -ResourceGroupName $resourcegroupName -AccountName $storageAccountNAme 

#Get Virtual Network configuration
$vnet = Get-AzureRmVirtualNetwork -Name $vnetName -ResourceGroupName $resourceGroupName 

# Create VM from an existing image
$OSDiskName="$vmName-C-01"
$vm = New-AzureRmVMConfig -vmName $vmName -vmSize $vmSize
$nic = New-AzureRmNetworkInterface -Name $nicName -ResourceGroupName $resourceGroupName -Location $location -SubnetId $vnet.Subnets[1].Id 
$vm = Add-AzureRmVMNetworkInterface -VM $vm -Id $nic.Id 
$destOSDiskUri = "https://destsa.blob.core.windows.net/vhds/destvhd.vhd"
$vm = Set-AzureRmVMOSDisk -VM $vm -Name $OSDiskName -VhdUri $destOSDiskUri -Windows -CreateOption attach
New-AzureRmVM -ResourceGroupName $resourceGroupName -Location $location -VM $vm

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