Troubleshooting full disks and disk resizing

Linux

This page describes common issues that you might run into when resizing a persistent disk or when your persistent disk is full, and how to fix each of them.

Before you begin

If you want to use the command-line examples in this guide, do the following:
1. Install or update to the latest version of the Google Cloud CLI.
2. Set a default region and zone.
If you want to use the API examples in this guide, set up API access.
Always create a snapshot of your disk before performing any troubleshooting steps to ensure that your data is backed up.

Disk capacity errors

Full disks

The following are common errors you might encounter when your persistent disk reaches full capacity. You might see these errors appear in a number of places, such as in your serial console output or in application logs.

No space left on device

Not enough storage is available to process this command

To resolve this issue, do the following:

Create a snapshot of the disk.
Delete files that you don't need on the disk to free up space.
If your disk requires more space after this, resize the disk.

Inaccessible VM due to full boot disk

Your VM might become inaccessible if its boot disk is full. This scenario can be difficult to identify; it's not always obvious when the VM connectivity issue is due to a full boot disk. The following are examples of common errors you might encounter if you cannot access your VM from the Google Cloud CLI because the boot disk is full:

  Network error: Software caused connection abort

  ERROR: (gcloud.compute.ssh) Could not SSH into the instance.  It is possible
  that your SSH key has not propagated to the instance yet. Try running this
  command again.  If you still cannot connect, verify that the firewall and
  instance are set to accept ssh traffic.

  You cannot connect to the VM instance because of an unexpected error. Wait a
  few moments and then try again.

```
  No space left on device
  
```

  ERROR Exception calling the response handler. [Errno 2] No usable temporary
  directory found in ['/tmp', '/var/tmp', '/usr/tmp', '/']...

To resolve the above issues, do the following:

Confirm that the VM's SSH failure is due to a full boot disk:
```
gcloud compute instances tail-serial-port-output VM_NAME
```
If the boot disk is full, the resulting output will contain the message No space left on device.
If you have not already done so, create a snapshot of the VM's boot disk.
Try to restart the VM.
If you still can't access the VM, do the following:
1. Stop the VM:
```
gcloud compute instances stop VM_NAME
```
  Replace VM_NAME with the name of your VM.
2. Increase the size of the boot disk:
```
gcloud compute disks resize BOOT_DISK_NAME --size DISK_SIZE
```
  Replace the following:
  - BOOT_DISK_NAME: the name of your VM's boot disk
  - DISK_SIZE: the new larger size, in gigabytes, for the boot disk
  For example, to resize a disk named example-disk-1 to 6GB, run the following command:
```
gcloud compute disks resize example-disk-1 --size=6GB
```
3. Start the VM:
```
gcloud compute instances start VM_NAME
```
Reattempt to SSH to the VM. If you still can't access the VM, do one of the following:
- Create a new disk from a snapshot. For more information, see Recovering an inaccessible VM or a full boot disk.
- Boot the VM temporarily in rescue mode, using open source GCE Rescue tool and perform the steps available in File system issues.

File system issues

File system resize

After you resize a VM boot disk, most VMs resize the root file system and restart the VM. However, for some VM images types, you might have to resize the file system manually. If your VM does not support automatic root file system resizing, or if you've resized a data (non-boot) persistent disk, you must manually resize the file system and partitions.

To check if your root file system expanded automatically after you resized your VM boot disk, do the following:

Check if your VM resized the boot disk using one of the following methods:
- Inspect your serial port output. Look for a line that indicates the root partition was resized.
  
  For example, on VMs with Debian images, if the automatic resize was successful then the console logs include the line ... expand-root.sh[..]: Resizing ext4 filesystem on /dev/sda1.
- If you can connect to a Linux VM using SSH, run the command df -h to check if there is free disk space.
  
  For example, this output shows that the root file system is 92% full:
```
Filesystem                                    Size  Used Avail Use% Mounted on
udev                                           63G     0   63G   0% /dev
tmpfs                                          13G  1.4M   13G   1% /run
/dev/sda1                                     339G  315G   24G  92% /
```
If your VM didn't resize the root file system, manually resize the file system and partitions.