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Attaching a disk to a VM

You can attach a disk to either a running or stopped virtual machine.

For a disk to be successfully attached to a running VM, the operating system must be ready to accept commands to attach disks. Before attaching a disk, make sure that the OS is loaded or stop the virtual machine, otherwise the attach disk operation fails. If an error occurs, stop the VM and repeat the operation.

When you select a disk to attach to a VM, you can specify whether that disk should be deleted when deleting the VM. You can choose this option when creating a VM, updating it, or attaching a new disk to it.

Attaching a disk

To attach a disk to a VM:

  1. Select the folder the VM belongs to.
  2. Select Yandex Compute Cloud.
  3. Go to Disks.
  4. Under Disks, select an unmounted disk or create a new one.
  5. Next to the desired disk, click and select Attach.
  6. In the window that opens:
    • In the VM field, select the virtual machine you want to mount your disk to.
    • Enter a Device name.
    • Select the value of the Delete automatically parameter.
  7. Click Attach.

If you don't have the Yandex.Cloud command line interface yet, install and initialize it.

The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name or --folder-id parameter.

  1. View a description of the CLI attach disk command:

    $ yc compute instance attach-disk --help

  2. Get a list of VMs in the default folder:

    $ yc compute instance list
+----------------------+-----------------+---------------+---------+----------------------+
|          ID          |       NAME      |    ZONE ID    | STATUS  |     DESCRIPTION      |
+----------------------+-----------------+---------------+---------+----------------------+
| fhm0b28lgfp4tkoa3jl6 | first-instance  | ru-central1-a | RUNNING | my first vm via CLI  |
| fhm9gk85nj7gcoji2f8s | second-instance | ru-central1-a | RUNNING | my second vm via CLI |
+----------------------+-----------------+---------------+---------+----------------------+

  3. Select the VM ID or NAME (for example, first-instance).

  4. Get a list of disks in the default folder:

    yc compute disk list

    Result:

    +----------------------+--------------+-------------+---------------+--------+----------------------+-------------------------+
|          ID          |     NAME     |    SIZE     |     ZONE      | STATUS |     INSTANCE IDS     |       DESCRIPTION       |
+----------------------+--------------+-------------+---------------+--------+----------------------+-------------------------+
| a7lqgbt0bb9s40tifuhc | first-disk   | 20401094656 | ru-central1-a | READY  | a7lcvu28njbhnkcteb5n |                         |
| a7lv5j5hm1p1hppprga7 | second-disk  | 21474836480 | ru-central1-a | READY  |                      |                         |
+----------------------+--------------+-------------+---------------+--------+----------------------+-------------------------+

  5. Select the ID or NAME of the required disk (for example, first-disk). To view a list of disks attached to the VM, run the command:

    $ yc compute instance get --full first-instance

  6. Attach the disk to the VM:

    $ yc compute instance attach-disk first-instance \
    --disk-name first-disk \
    --mode rw

    To automatically delete the disk when deleting the VM, set the --auto-delete flag.

    Note

    Empty disks do not have a file system. If you attach an empty disk, partition and mount it manually. Alternatively, instead of attaching an empty disk, you can create a snapshot of the boot disk and create a VM based on the snapshot.

    If an error occurs, stop the virtual machine:

    $ yc compute instance stop first-instance

    Then reattach the disk.

  7. If the virtual machine was stopped, restart it:

    $ yc compute instance start first-instance

Use the attachDisk method for the Instance resource.

Mounting a disk created from a snapshot or image

To use the attached disk:

Mount the disk:

  1. Connect to the VM via SSH.

  2. Run the blkid command and make sure that there are no partitions with duplicate UUIDs:

    $ sudo blkid
/dev/vda2: UUID="0d6dfef0-542d-47ba-b55b-18ab5f5f9210" TYPE="ext4" PARTUUID="752aa845-94ee-4850-9188-71c2f919ee7b"
/dev/vdb2: UUID="0d6dfef0-542d-47ba-b55b-18ab5f5f9210" TYPE="ext4" PARTUUID="752aa845-94ee-4850-9188-71c2f919ee7b"
...

  3. If there are, generate a new UUID for the duplicates that come last in the blkid command output. In the example from the previous step, you need to generate a UUID for the /dev/vdb2 partition:

    $ sudo e2fsck -f /dev/vdb2
$ sudo tune2fs -U $(uuidgen) /dev/vdb2

    This method works for partitions with ext2, ext3, and ext4 file systems. The latter is used in the Linux images provided by Yandex.Cloud. The file system type is returned by the blkid command in the TYPE parameter.

    If you use another filesystem, run the suitable command. For example, to generate a UUID for XFS, run the following:

    $ sudo xfs_admin -U generate /dev/vdb2

    To see if the UUID changed, run the blkid command again:

    $ sudo blkid
/dev/vda2: UUID="0d6dfef0-542d-47ba-b55b-18ab5f5f9210" TYPE="ext4" PARTUUID="752aa845-94ee-4850-9188-71c2f919ee7b"
/dev/vdb2: UUID="ea004485-07fb-4128-b20d-e408db1e8ae8" TYPE="ext4" PARTUUID="752aa845-94ee-4850-9188-71c2f919ee7b"

    When creating a snapshot or image in Linux, the UUID and PARTUUID of disk partitions are saved. Linux uses this data when mounting partitions, including the root one, so the IDs must be unique. For example, if you clone a boot disk and attach it to the same VM, two partitions with the same UUIDs appear on the VM. As a result, after starting the VM, the root partition may not be the one you specified as the boot disk.

  4. Mount disk partitions using the mount utility. For example, mount the vdb2 partition to the /mnt directory:

    sudo mkdir /mnt
sudo mount /dev/vdb2 /mnt

  5. Run the df command to check the state of the file system.

  1. Connect to the VM via RDP.

  2. Assign a letter to the attached disk. For information about how to do this, see the Microsoft documentation.

Partitioning and mounting an empty disk

To partition and mount an empty disk yourself:

  1. Check if the disk is attached as a device and get its path in the system:

    lsblk

    Command execution result:

    NAME   MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda    252:0    0  13G  0 disk
├─vda1 252:1    0   1M  0 part
└─vda2 252:2    0  13G  0 part /
vdb    252:16   0   1G  0 disk

    An empty disk is usually labeled /dev/vdb.

  2. Partition your disk. To do this, create partitions using cfdisk, fdisk, or parted.

  3. Format the disk for the appropriate file system. For example, you can use the mkfs utility.

  4. Mount disk partitions using the mount utility. For example, mount the vdb2 partition to the /mnt directory:

    sudo mkdir /mnt
sudo mount /dev/vdb2 /mnt

  5. Check the file system status:

    df

    Command execution result:

    Filesystem     1K-blocks    Used Available Use% Mounted on
udev              989424       0    989424   0% /dev
tmpfs             203524     816    202708   1% /run
/dev/vda2       13354932 2754792  10015688  22% /
tmpfs            1017608       0   1017608   0% /dev/shm
tmpfs               5120       0      5120   0% /run/lock
tmpfs            1017608       0   1017608   0% /sys/fs/cgroup
tmpfs             203520       0    203520   0% /run/user/1000
/dev/vdb2         523260    3080    520180   1% /mnt

  1. Run the Computer Management tool as an administrator.

  2. Under Storage, select Disk Management.

  3. Initialize the disk. To do this, right-click on the empty disk and select Initialize Disk. This opens the Initialize Disk dialog.

  4. Select a partition style and click ОК.

  5. Create partitions on the disk. To do this, right-click on the empty disk and select New Simple Volume.

  6. Use the New Simple Volume Wizard to set the desired partition size, assign a drive letter, and specify the file system type.

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