CODEWITHSUNDEEP
amazon-web-servicessnapshot
user1154422
user1154422

Reputation: 656

Creating a complete copy of an AWS EBS volume from a snapshot

To Devs, I am getting lazy reads when I create an EBS volume from a snapshot and attach it to an EC2 node.
I would like to create an EBS volume with a complete copy so that the first read is not slow.
Is there a way to do this? Thanks, Marc

Upvotes: 3

Views: 923

Answers (1)

guest
guest

Reputation: 76

You and everybody else. According to an AWS rep that I talked with at the AWS Summit in NYC, Amazon is well aware of the issue. Of course, there's a difference between "being aware" of an issue and actually fixing it ...

For now, the best you can do is follow the AWS instructions and use dd or fio to touch every block on the device before it's mounted. The benefit of fio is that it will run parallel threads.

Beware that you will be limited by the IO performance of your volume. One IO is 16k on an gp2 volume, so divide your volume size by that to determine how many IOs it will take to touch every block, and then divide that by the IOPS for your volume (taking into account burst IOPS).

For example (and these are rough numbers!), a 1 TB volume will require 67,108,864 IOs to read fully. The default non-provisioned performance of a 1TB gp2 volume is 3,000 IOPS, this will take 22,369 seconds or somewhat more than 6 hours. Smaller volumes will be able to use burst IOPS to get above their basic allotment, but may run into throughput limits.

Upvotes: 6

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