Average image file sizes and compression rates

Hello, I'm trying to figure out how much storage space we'd need to purchase if we adopted the following backup & collapsing process using ShadowProtect Server edition:

Specifically, I'm trying to come up with a metric/multiplier/percentage that I can use to figure out how much storage would be required to accommodate the initial base image, and what the file sizes we could expect to see with each of the various daily/weekly/monthly synthetic incremental backup files.

Has anybody developed any rules of thumb to size a storage device based on the initial base image size, accounting for compression, collapsing regime, data growth, etc?

For example, consider the following backup regime for a server with a 100GB base image:

  • Initial base image (kept indefinitely)
  • Hourly incrementals (kept for 7 days)
  • Synthetic Daily Incrementals (kept for 14 days)
  • Synthetic Weekly Incrementals (kept for 5 weeks)
  • Synthetic Monthly Incrementals (kept for 12 months) 

How much storage space would I need to purchase to accomplish this?I realize that this is largely dependent on the amount of data that is changed on the server, but I'm hoping that folks can share what they're seeing in their environments so I can come up with some rough guidelines. Even better, would be a handy chart direct from StorageCraft that I could use to estimate storage capacities taking in to account incremental file size (relative to the base image) with and without average compression rates.Thanks in advance,




Re: Average image file sizes and compression rates

 I have two comments for you.

First, the current implementation of ImageManager never deletes any of the older synthetic incrementals.  It only deletes the older intra-daily (non-synthetic) incrementals, per the policy that you specify.  This ensures that you will always have at least one end-of-day backup for every single day back to the base (assuming that ShadowProtect generated at least one intra-daily (non-synthetic) incremental for each day).  We are planning on adding additional functionality which will enable you to prune out older daily and older weekly synthetic incremental backups per a policy that you set.

Secondly, it's an unfortunate fact that, as you say, the required storage space is "largely dependent on the amount of data that is changed."  In fact, this is such an over-arching factor in determining the required space that it is impossible to accurately determine the required space without a detailed knowledge of your particular use case and exactly how much data changes on your disk each day, and how much of that changed data is new data vs modified data.  If you can work out these two numbers, then you should be able to calculate the required capacity of your repository.

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