S3 continuous backup growing month over month


I have AWS backup plan setup to backup a few S3 resources using continuous backup with 35 day retention to a backup vault with lock enabled.

The s3 buckets are approx. 7.5 TB in size total.

I started backing up some time in March. Every month since my AWS backup bill increases in size while the size of my S3 buckets have remained fairly consistent (if not reduced in size).

april: $0.05 per GB-month for warm backup storage for S3 -- 10,726.497 GB-month may: 13,587.932 GB-month jun: 14,464.78 GB-month jul: 16,523.482 GB-month

For example. In July my S3 storage was just about 7.1 TB according to billing yet billed s3 backup storage was 16TB. I understand that the PITR backups will be larger due to changes but I don't understand why it's 10TB larger and growing consistently each month. There does not appear to be any reliable to check backup vault/job size when continuous backups are involved.

Is there something I'm missing here or perhaps some issue with using locked vaults in conjunction with continuous backups?

asked 8 months ago422 views
1 Answer
  1. Go to Cost Explorer -> Choose Date Range in right pane
  2. Granularity -> Daily
  3. Dimension -> Usage Type
  4. Service -> Backup

This would show you what are the things, that are getting billed under AWS backup.

On your question, total s3 storage is ~7TB and AWS back up is charging for ~16TB:

It'd depend on what type of backup you have configured with AWS backup, continuous backups and periodic backups. AWS backup works with versioned bucket and if you'd have chosen continuous backup, then there are fair chances that, even with total s3 storage of 7TB, AWS backup would have backed up much more data as it takes back up for point in time recovery.

If you have configured periodic backup, then also, what is the back up frequency depending upon that, AWS back up would have backed up much more data than total s3 storage.

AWS backup pricing is based on multiple factors and storage, expected data change rate, retention period are some of the major factors. On these factors AWS backup takes backup and charge accordingly.

I'd suggest you to revise your AWS backup configuration, if you think, this is backing up quite frequently, too much of data then tweak the configuration and monitor it for subsequent days.

I'd strongly recommend you to do a rough estimate of back up pricing from AWS Backup pricing calculator page. Also refer AWS Backup pricing and examples given at the very last of this page.

Hope this explanation helps you in understanding why you see much more backed up data by AWS backup than actual total s3 storage.

Comment here if you have additional questions, happy to help.


profile pictureAWS
answered 8 months ago
  • The only backup enable for S3 is the continuous backup with 35 day retention. Unfortunately the price calculator does not support continuous backup.

    Cost explorer with daily on range from april 1st to today basically just shows a consistent uptrend from approx $15/day to $30/day

    I still don't understand how or why the backup size is growing and never going down.

  • What is backup frequency?

  • The frequency was set to weekly but I've recently changed it to monthly. Although it's not clear to me how the frequency impacts continuous backups (if at all).

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