AWS::EC2::Instance refuses to boot. Mounting the wrong drive as root? - amazon-ec2

Question

I am attempting to provision a few EC2 instances that need multiple EBS drives. I am attempting to define the root volume and 4 other volumes through BlockDeviceMappings.
Problem:
As far as I can tell, the code below conforms to any example I have seen online. But when Windows boots up, it dies instantly. And looking at the EC2 console (screenshot), I can see that the instance has seven EBS volumes attached (instead of 5) and that /dev/xda is set to root instead of /dev/sda1.
"Mappings" : {
"AWSRegionToAMI" : {
"us-east-1" : { "Windows2012R2" : "ami-5d1b984a" },
"us-west-1" : { "Windows2012R2" : "ami-07713767" },
"us-west-2" : { "Windows2012R2" : "ami-241bd844" }
},
"VolumeSize" : {
"DataDrive" : { "Size" : "50" },
"LogDrive" : { "Size" : "50" },
"TempDrive" : { "Size" : "400" },
"BackupDrive" : { "Size" : "100" }
},
"stackmap" : {
"sqlha" : {
"Name": "MS SQL Server 2014 Always On",
"chefjson" : "https://s3.amazonaws.com/[redacted]",
"os" : "win",
"bootstrapurl" : "https://s3.amazonaws.com/[redacted]"
}
}
},
"WSFCNode1": {
"Type": "AWS::EC2::Instance",
"Properties": {
"ImageId" : { "Fn::FindInMap" : [ "AWSRegionToAMI", { "Ref" : "AWS::Region" }, "Windows2012R2" ] },
"InstanceType": { "Ref": "InstanceType" },
"EbsOptimized": "true",
"NetworkInterfaces": [
{
"DeleteOnTermination": "true",
"DeviceIndex": 0,
"SubnetId": { "Ref": "PrivateSubnet1ID" },
"SecondaryPrivateIpAddressCount": 2,
"GroupSet": [
{ "Ref": "WSFCSecurityGroup" },
{ "Ref": "WSFCClientSecurityGroup" }
]
}
],
"BlockDeviceMappings": [
{
"DeviceName": "/dev/sda1",
"Ebs" : {"VolumeSize": "60"}
},
{
"DeviceName": "/dev/xvdb",
"Ebs" : {"VolumeSize": { "Fn::FindInMap" : [ "VolumeSize", "DataDrive", "Size" ]} }
},
{
"DeviceName": "/dev/xvdc",
"Ebs" : {"VolumeSize": { "Fn::FindInMap" : [ "VolumeSize", "LogDrive", "Size" ]} }
},
{
"DeviceName": "/dev/xvdd",
"Ebs" : {"VolumeSize": { "Fn::FindInMap" : [ "VolumeSize", "TempDrive", "Size" ]} }
},
{
"DeviceName": "/dev/xvde",
"Ebs" : {"VolumeSize": { "Fn::FindInMap" : [ "VolumeSize", "BackupDrive", "Size" ]} }
}
],
"KeyName": { "Ref": "KeyPairName" },
"UserData" : { "Fn::Base64" : { "Fn::Join" : ["", [
"<powershell>\n",
"# Disable UAC and allow scripts to run\n",
"New-ItemProperty -Path HKLM:Software\\Microsoft\\Windows\\CurrentVersion\\policies\\system -Name EnableLUA -PropertyType DWord -Value 0 -Force\n",
"Set-ExecutionPolicy Unrestricted -force\n",
"c:\\windows\\System32\\WindowsPowershell\\v1.0\\powershell.exe -noninteractive -noprofile Set-ExecutionPolicy unrestricted -force\n",
"c:\\windows\\syswow64\\windowspowershell\\v1.0\\powershell.exe -noninteractive -noprofile Set-ExecutionPolicy unrestricted -force\n",
"#Change TimeZone\n",
"tzutil /s ", {"Ref" : "Timezone"}, "\n",
"#Run Bootstrap PS1\n",
"$newname = '", { "Fn::Join" : ["", [{"Ref" : "Environment"}, {"Ref" : "Location"}, {"Ref" : "Stack"}, {"Ref" : "Role"} ]]},"'\n",
"$region = '", {"Ref" : "VPCRegion"}, "'\n",
"$role = '", {"Ref" : "Role"}, "'\n",
"$chef_rb = '", { "Fn::FindInMap" : [ "stackmap", { "Ref" : "Role" }, "chefjson"]}, "'\n",
"mkdir 'c:\\temp' -force\n",
"(new-object System.Net.WebClient).DownloadFile( 'https://s3.amazonaws.com/[redacted]', 'c:\\temp\\bootstrap.ps1')\n",
"powershell c:\\temp\\bootstrap.ps1 -newname $newname -region $region -role $role -chef_rb $chef_rb -logfile c:\\temp\\bootstrap.log -verbose true\n",
"#Reboot if needed\n",
"Start-Sleep -s 10\n",
"Restart-Computer\n",
"mkdir 'c:\\temp\\cf_reboot_cmd_ran' -force\n",
"shutdown -r\n",
"mkdir 'c:\\temp\\cf_shut_cmd_ran' -force\n",
"Start-Sleep -s 10\n",
"mkdir 'c:\\temp\\cf_ran_again' -force\n",
"</powershell>"
] ] }
},
"Tags": [
{ "Key": "Name", "Value": "SQL Node 1" }
]
}
},
Confusingly, even when I drop all the extra drives and just do a block device mapping of one disk
"BlockDeviceMappings": [
{
"DeviceName": "/dev/sda1",
"Ebs" : {"VolumeSize": "60"}
}
],
...I still end up with three volumes, and the wrong one (/dev/xda) assigned as root. Screenshot.
Is this a Windows thing? What do my block device mappings need to look like to mount correctly as root (or C:, in this case)?

Answer 1

Nevermind. Root problem was in the AMI I chose. Once I selected a proper Windows AMI, everything worked perfectly.
For anybody else running into this problem, double check your AMI selection.