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Feedback: Volume Mounting Conflict Due to Duplicate Filesystem UUID
Dear AWS Support,
I’d like to report a situation that I believe warrants additional safeguards on the AWS platform. I recently launched a new EC2 Ubuntu 22.04 instance from an AMI that was created from another instance’s root volume. The original instance mounted a root volume and a backup volume, the latter of which was identified by a UUID. Because /etc/fstab was the same on both instances, the new instance inherited the same filesystem UUID for the backup volume, due to the AMI being a snapshot of the original root volume. (The original root volume was not specified using a UUID.)
This caused a conflict where the original instance was no longer able to mount the backup volume (with a matching XFS UUID), even though the second instance never successfully mounted it. The resulting error was confusing and disrupted operations until we realized that the duplicate UUIDs were the cause.
While I acknowledge that system design is ultimately the user’s responsibility, this kind of conflict is subtle and hard to anticipate. I suggest that AWS consider implementing a safeguard such as: • Warning users when launching an instance from an AMI that shares a filesystem UUID with an actively mounted volume • Offering an option to automatically randomize or regenerate UUIDs for volumes when creating AMIs • Adding volume-level UUID conflict detection on instance launch or attachment
Preventing or flagging these conditions could help avoid data disruption and make troubleshooting easier for users.
Thank you for your consideration.
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Volume Mounting Conflict Due to Duplicate Filesystem UUIDs in Cloned Instances
To AWS Support,
I'd like to report a volume-mounting issue that may warrant deeper safeguards within the AWS platform.
Issue Summary: I recently launched a new EC2 Ubuntu 22.04 instance from an AMI created from another EC2 instance’s root volume. Both the original and clone instances were configured to mount:
A root volume (not referenced by UUID)
A backup volume (referenced in /etc/fstab by UUID)
Because the clone’s root volume was created via snapshot from the original instance, both ended up with identical XFS filesystem UUIDs.
Although the clone instance never successfully mounted the backup volume, the original instance’s mount operation failed with a UUID conflict error. It took significant investigation to determine that this was due to the duplicate UUIDs originating from the AMI creation process.
Impact: The original instance's backup volume could no longer be mounted
This resulted in operational disruption and downtime
The issue was not intuitive and required manual UUID regeneration (xfs_admin -U) and system reconfiguration
🛠️ Suggestions for AWS Safeguards: Launch-Time Conflict Warnings: Detect and warn users if an instance is about to mount a volume with a duplicated filesystem UUID from another active instance.
Optional UUID Regeneration During AMI Creation: Add an option during AMI or snapshot creation to regenerate UUIDs, especially for volumes intended for reuse.
Attachment-Level UUID Detection: At the time a volume is mounted or attached, detect UUID conflicts and offer safe guidance or block the mount temporarily.
Conclusion: While users bear responsibility for managing volume configurations, this is a non-obvious failure mode that can seriously impact operations — especially in environments where AMIs are regularly cloned for scaling, failover, or testing.
Thanks for considering these enhancements. Adding safeguards would reduce downtime and significantly improve the user experience for EC2-based deployments.
Sincerely, [Your Name / AWS Account ID if needed]
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