When creating a Linux Azure VM with "temp disk" (locally SSD) such as D2ds_v4, the disk is formatted ext4 and already mounted at /mnt via some mechanism. This is annoying for me because I don't want it formatted ext4, and I certainly don't want it mounted at /mnt (which seems strange: drives should be mounted at a subdirectory of /mnt not at the directory itself). How can I prevent this so I can format the disk myself?

Hi Travis, You can use cloud-init custom data to modify vm provisioning. For example, I just did quick test by using below on Advanced tab when creating VM in portal: #cloud-config device_aliases: {'ephemeral0': '/dev/sdb'} disk_setup: ephemeral0: table_type: mbr layout: True overwrite: False fs_setup: - label: ephemeral0 filesystem: ext3 device: ephemeral0.1 replace_fs: ntfs mounts: - [ ephemeral0, /mnt/resource, auto, "defaults,nofail", "0", "2" ] Please see result in screenshot: Configure partitions and filesystems https://cloudinit.readthedocs.io/en/latest/reference/yaml_examples/disk_setup.html#set-up-the-filesystem Cloud-init Overview https://learn.microsoft.com/en-us/azure/virtual-machines/linux/using-cloud-init Custom data and cloud-init on Azure Virtual Machines https://learn.microsoft.com/en-us/azure/virtual-machines/custom-data Please click Accept Answer and upvote if the above was helpful. Thanks. -TP

Unwanted formatting & mounting of temp drive

Accepted answer

TP 99,371 Reputation points

2024-11-14T20:29:19.3633333+00:00
Hi Travis,

You can use cloud-init custom data to modify vm provisioning. For example, I just did quick test by using below on Advanced tab when creating VM in portal:

#cloud-config device_aliases: {'ephemeral0': '/dev/sdb'} disk_setup: ephemeral0: table_type: mbr layout: True overwrite: False fs_setup: - label: ephemeral0 filesystem: ext3 device: ephemeral0.1 replace_fs: ntfs mounts: - [ ephemeral0, /mnt/resource, auto, "defaults,nofail", "0", "2" ]

Please see result in screenshot:

Configure partitions and filesystems

https://cloudinit.readthedocs.io/en/latest/reference/yaml_examples/disk_setup.html#set-up-the-filesystem

Cloud-init Overview

https://learn.microsoft.com/en-us/azure/virtual-machines/linux/using-cloud-init

Custom data and cloud-init on Azure Virtual Machines

https://learn.microsoft.com/en-us/azure/virtual-machines/custom-data

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP
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Mahesh Goud Juvvadi 1,550 Reputation points Microsoft Vendor

2024-11-15T17:40:20.3966667+00:00

Hi Travis Downs,

Just checking in to see if you have got a chance to see the answer posted by @TP in resolving the issue.

If it was helpful, please click "Upvote and Accept Answer" on his post to let us know.

We're here to help, so if you have any further questions, don't hesitate to ask.

Thank You.

Travis Downs 40 Reputation points

2024-11-15T20:11:01.78+00:00

Thanks, I'm looking at this! One thing I noticed is that the temp drive seems to flip random between /dev/sda or /dev/sdb, i.e., if I start several VMs, some will map the OS drive to a and temp drive to b, and some will use the reverse, so not sure if the mapping part above is reliable.

TP 99,371 Reputation points

2024-11-15T21:32:36.4966667+00:00

You can remove device_aliases line from the above and it still works (I tested). According to the docs there is automatic alias for ephemeral<X>, excerpt below:

For convenience, aliases can be specified for disks using the device_aliases config key, which takes a dictionary of alias:`` ``path mappings. There are automatic aliases for swap and ephemeral<X>, where swap will always refer to the active swap partition and ephemeral<X> will refer to the block device of the ephemeral image.

Mahesh Goud Juvvadi 1,550 Reputation points Microsoft Vendor

2024-11-18T17:17:46.9233333+00:00

Hi Travis Downs,

Just checking in to see if you have got a chance to see the latest comment posted by @TP in resolving the issue.

If it was helpful, please click "Upvote and Accept Answer" on his post to let us know.

Thank you.

Travis Downs 40 Reputation points

2024-11-18T19:20:58.3566667+00:00

It has been very helpful and much appreciated. I haven't tested it yet but I will return and accept it when I complete testing. Thanks!

Mahesh Goud Juvvadi 1,550 Reputation points Microsoft Vendor

2024-11-19T20:28:31.7133333+00:00

Hi Travis Downs,

Thank you for taking time and responding, I hope you have tested it from your end.

If it was helpful, please click "Upvote and Accept Answer" on his post to let us know.

Thank you.

Travis Downs 40 Reputation points

2024-11-21T02:48:44.78+00:00

I accepted this answer although it did not ultimately answer the direct question posed: it is not possible to prevent the formatting of the drive using cloud-init, as far as I can tell, though it does allow you to change how it is formatted. If you configure cloud-init to not format it at all, the drive still appears, now formatted as NTFS.

Mahesh Goud Juvvadi 1,550 Reputation points Microsoft Vendor

2024-11-22T17:32:22.17+00:00

Hi Travis Downs,

I Appreciate your efforts and thanks for sharing your insights.
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