/etc/fstab entry for temporary filesystem in linux

Question

Hi Team, /etc/fstab entries for the temporary mount is managed by azure or need to do manually. We are using this temporary storage for the /mnt directory where the azure swap file is configured. We have noticed in fstab that the device path of temp storage was wrong, we have made the changes manually to point to the right one. Is it the proper way to do it. ex. In /etc/fstab earlier entry was /dev/disk/cloud/azure_resource,I have manually changed it to dev/disk/cloud/azure_resource-part1. After that the fs mounted properly and working fine. Is it right way?

Answer 1

Hello vinothkaliaperumal-2643,

It seems like you're discussing the management of temporary storage and the /etc/fstab entries in an Azure environment. Let me address your questions and concerns:

• Managing /etc/fstab Entries: In most cases, /etc/fstab entries for mounting filesystems need to be managed manually. While some cloud platforms provide automation tools or scripts for managing certain mounts, such as Azure's custom script extension or cloud-init, the entries in /etc/fstab are generally controlled by the user or administrator. It's not uncommon for administrators to modify these entries manually to ensure proper mounting.
• Azure Temporary Storage: In Azure VMs, the temporary storage is a local disk that is attached to the VM and can provide high-speed storage for temporary data. This storage is ephemeral, meaning its content is not persisted across VM reboots. It's commonly used for things like swap space or temporary files.
• Modifying /etc/fstab Entries: If you found that the device path in your /etc/fstab entry was incorrect and you manually updated it to the correct path, that's a valid approach. This would ensure that the correct device is mounted at the specified mount point. However, keep in mind that manual changes can introduce human error, so it's important to be cautious when modifying system configuration files.
• Device Path: In your example, it seems that the correct device path is /dev/disk/cloud/azure_resource-part1. If you have confirmed that this is the correct path for the temporary storage device, then updating the /etc/fstab entry to point to this path is appropriate.
• Verifying the Change: After making changes to the /etc/fstab file, it's recommended to test the configuration by rebooting the system or using the mount -a command to apply the changes without a reboot. This will help ensure that the system successfully mounts the temporary storage using the updated configuration.
• Automation: To streamline such changes and ensure consistency across multiple VMs or instances, you might consider using configuration management tools like Ansible, Puppet, or Chef. These tools can help automate the process of managing configuration files, including /etc/fstab entries. Remember that any changes to critical system files like /etc/fstab should be performed carefully and with proper backups or snapshots in place, especially in a production environment. If you have any further questions please let me know.

Answer 2

Hello @Vinoth Kaliaperumal

Thank you for reaching out to the Microsoft Q&A platform.

In Azure, the temporary storage (also known as the ephemeral storage) is provided by the local disk on the virtual machine and is typically mounted at /mnt on Linux-based virtual machines. This temporary storage is not managed by Azure's Disk service and is not persistent; it is meant for temporary data storage and can be used for things like swap files, caching, or other temporary files.

The /etc/fstab file is used to configure the mounting of file systems during the boot process. If the entry for the temporary storage in /etc/fstab was incorrect, and you have manually corrected it to point to the right device path (/dev/disk/cloud/azure_resource-part1 in your case), that's generally the correct way to do it to ensure that the temporary storage is mounted correctly

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