i am using this template to create aws resources. my count is 2, every thing is getting created as per plan,, i am attaching a 2nd ebs volume of 1 gb to both machines, which is also happening well, but the only issue is when i try to delete one ec2 instance by below cmd,, both of the 2nd ebs volume of 1gb are getting destory,,i checked they are connected on seperate instances.

THis is the main.tf

# Define webserver inside the public subnets 
resource "aws_instance" "jumpserver" {
  count                       = "${var.num_of_instances}"
  ami                         = "${var.ami}"
  instance_type               = "t2.micro"
  key_name                    = "${aws_key_pair.ProdKeypair.id}"
  subnet_id                   = "${aws_subnet.public_subnet.id}"
  vpc_security_group_ids      = ["${aws_security_group.sg_internet_facing.id}"]
  associate_public_ip_address = true
  source_dest_check           = false
  #   user_data = "${file("install.sh")}"

  root_block_device = {
    volume_type           = "gp2"
    volume_size           =  "8"  
    delete_on_termination = "${var.delete_on_termincation}"
  }

  tags {
    Name = "${format("jump-%01d",count.index+1)}"
  }

  provisioner "remote-exec" {
    inline = ["sudo apt-get  -y install python"]

    connection {
      type        = "ssh"
      user        = "ubuntu"
      private_key = "${file(var.private_key_path)}"
    }
  }
}

resource "aws_ebs_volume" "vol_generic_data" {
  size              = "1"
  count             = "${var.num_of_instances}"
  type              = "gp2"
  availability_zone = "${element(aws_instance.jumpserver.*.availability_zone, count.index)}"

 tags = {
    Name = "${format("jump-%01d",count.index+1)}"
  }
}


resource "aws_volume_attachment" "generic_data_vol_att" {
  device_name = "/dev/xvdf"
  volume_id   = "${element(aws_ebs_volume.vol_generic_data.*.id, count.index)}"
  instance_id = "${element(aws_instance.jumpserver.*.id, count.index)}"
  count       = "${var.num_of_instances}"
}


# Define webserver inside the private subnet
resource "aws_instance" "backendserver" {
  ami                         = "${var.ami}"
  instance_type               = "t2.micro"
  key_name                    = "${aws_key_pair.ProdKeypair.id}"
  subnet_id                   = "${aws_subnet.private_subnet.id}"
  vpc_security_group_ids      = ["${aws_security_group.sg_backend.id}"]
  associate_public_ip_address = false
  source_dest_check           = false
  user_data                   = "${file("install.sh")}"

  tags {
    Name = "backendserver"
  }
}

I am using a terraform template to create AWS resources. My count is 2, everything gets created as per plan, and, I am attaching a 2nd EBS volume of 1 GB to both machines, which is also happening well.

However, the only issue is when I try to delete one EC2 instance using the command below, both of the 2nd EBS volumes of 1 GB are getting destroyed. I checked they are connected on separate instances.

This is the main.tf:

    # Define webserver inside the public subnets 
    resource "aws_instance" "jumpserver" {
      count                       = "${var.num_of_instances}"
      ami                         = "${var.ami}"
      instance_type               = "t2.micro"
      key_name                    = "${aws_key_pair.ProdKeypair.id}"
      subnet_id                   = "${aws_subnet.public_subnet.id}"
      vpc_security_group_ids      = ["${aws_security_group.sg_internet_facing.id}"]
      associate_public_ip_address = true
      source_dest_check           = false
      #   user_data = "${file("install.sh")}"
    
      root_block_device = {
        volume_type           = "gp2"
        volume_size           =  "8"  
        delete_on_termination = "${var.delete_on_termincation}"
      }
    
      tags {
        Name = "${format("jump-%01d",count.index+1)}"
      }
    
      provisioner "remote-exec" {
        inline = ["sudo apt-get  -y install python"]
    
        connection {
          type        = "ssh"
          user        = "ubuntu"
          private_key = "${file(var.private_key_path)}"
        }
      }
    }
    
    resource "aws_ebs_volume" "vol_generic_data" {
      size              = "1"
      count             = "${var.num_of_instances}"
      type              = "gp2"
      availability_zone = "${element(aws_instance.jumpserver.*.availability_zone, count.index)}"
    
     tags = {
        Name = "${format("jump-%01d",count.index+1)}"
      }
    }
    
    
    resource "aws_volume_attachment" "generic_data_vol_att" {
      device_name = "/dev/xvdf"
      volume_id   = "${element(aws_ebs_volume.vol_generic_data.*.id, count.index)}"
      instance_id = "${element(aws_instance.jumpserver.*.id, count.index)}"
      count       = "${var.num_of_instances}"
    }
    
    
    # Define webserver inside the private subnet
    resource "aws_instance" "backendserver" {
      ami                         = "${var.ami}"
      instance_type               = "t2.micro"
      key_name                    = "${aws_key_pair.ProdKeypair.id}"
      subnet_id                   = "${aws_subnet.private_subnet.id}"
      vpc_security_group_ids      = ["${aws_security_group.sg_backend.id}"]
      associate_public_ip_address = false
      source_dest_check           = false
      user_data                   = "${file("install.sh")}"
    
      tags {
        Name = "backendserver"
      }
    }