I am sort of confused about two AWS::EC2::Instance properties:
BlockDeviceMappings
and Volumes
.
I have read documentation a number of times but still don't really understand the difference.
Here is my template:
{
"AWSTemplateFormatVersion" : "2010-09-09",
"Description" : "kappoowTest",
"Mappings" : {
"AmazonLinuxAMI" : {
"eu-west-1" :
{ "AMI" : "ami-d8f9f1ac" },
"us-west-1" :
{ "AMI" : "ami-b63210f3" }
}
},
"Resources" : {
"SomeInstance" :{
"Type" : "AWS::EC2::Instance",
"Properties" : {
"AvailabilityZone" : "eu-west-1a",
"BlockDeviceMappings" : [
{
"DeviceName" : "/dev/sdc",
"Ebs" : { "VolumeSize" : "50" }
},
{
"DeviceName" : "/dev/sdd",
"Ebs" : { "VolumeSize" : "100" }
}
],
"DisableApiTermination" : "true",
"EbsOptimized" : "true",
"ImageId" : { "Fn::FindInMap" : [ "AmazonLinuxAMI", { "Ref" : "AWS::Region" }, "AMI" ]},
"InstanceType" : "m1.large",
"KeyName" : "mongo_test",
"Monitoring" : "true",
"SecurityGroups" : [ "default" ],
"Volumes" : [
{ "VolumeId" : { "Ref" : "NewVolume" }, "Device" : "/dev/sdk" }
]
}
},
"NewVolume" : {
"Type" : "AWS::EC2::Volume",
"Properties" : {
"Size" : "100",
"AvailabilityZone" : "eu-west-1a"
}
}
}}
Here I have created 3 volumes. 2 with
"BlockDeviceMappings" : [
{
"DeviceName" : "/dev/sdc",
"Ebs" : { "VolumeSize" : "50" }
},
{
"DeviceName" : "/dev/sdd",
"Ebs" : { "VolumeSize" : "100" }
}
]
and another one with:
"Volumes" : [
{ "VolumeId" :
{ "Ref" : "NewVolume" }, "Device" : "/dev/sdk" }
]
CloudFormation ran fine, but I fail to see the difference.
Could someone tell me what which way is better of adding EBS volumes to EC2 instance and what is the difference between these two methods ?