CODEWITHSUNDEEP
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Deb
Deb

Reputation: 337

EBS volume resize precautions

On one of my AWS instances running Ubuntu 16.04, I've a MySQL replica database on a 1TB ext4 EBS volume. I plan to increase it to 2TB. Before I increase the size of the volume and extend the filesystem using the resize2fs command, do I need to take any precautions? Is there any possibility of data corruption? If so would it be sane to create a EBS snapshot of this volume?

Upvotes: 0

Views: 569

Answers (1)

Michael - sqlbot
Michael - sqlbot

Reputation: 179124

Do I need to take any precautions?

You shouldn't need to take any unusual precautions -- just standard best practices, like maintaining backups and having a tested recovery plan. Anything can go wrong at any time, even when you're sitting, doing nothing.

Important

Before modifying a volume that contains valuable data, it is a best practice to create a snapshot of the volume in case you need to roll back your changes.

https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ebs-modify-volume.html

But this is not indicative of the operation being especially risky. Anecdotally, I've never experienced complications, and have occasionally resized an EBS volume and then its filesystem under a live, master, production database.

Is there any possibility of data corruption?

The possibility of data corruption is always there, no matter what you are doing... but this seems to be a safe operation. The additional space becomes available immediately, and there is no I/O freeze or disruption.

If so would it be sane to create a EBS snapshot of this volume?

As noted above, yes.

Concerns about errors creeping in later are valid, but EBS maintains internal consistency checks and will disable a volume if this fails to help avoid further scrambling of data so that you can do a controlled recovery and repair operation.

This would not help if EBS is prefectly storing data that was corrupted by something on the instance, such as might be caused by a defect in resize2fs, but it seems to be a solid utility. It doesn't move your existing data -- it just fleshes out the filesystem structures as needed to the filesystem use the entire free space that has become available.

Upvotes: 1

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