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Cloud Storage Gateway Benefits Abound

Last time, I gave a overview on cloud storage gateways. This time, I'll talk about the benefits you can get from using a CSG as your storage target for your image-based VM backups, and how your backup software can make the solution more effective.

CSGs are used to transfer data, including backup images, to a storage-as-a-service provider. CSGs can run on physical or virtual machines and hold data on the LAN until it is time to transfer to the cloud. Users access data through the LAN connection, instead of the slower WAN.

Speed is one of the big benefits to using a CSG together with an image-based backup solution. There are cost and convenience benefits as well – provided the backup solution has the features and functionality needed to optimize CSG use.

So, what are the benefits of using a cloud storage gateway with image-level backups? I see four major ones:

  1. When you go to the cloud, you might be able to leave your tape behind. Using a CSG allows you to keep your backups off site and recover them locally, even at the image or file level. Cloud CSGs also provide a DR option, because most of them can be installed in another location, and allow you to connect to your existing data in the cloud. Once you have a CSG set up and working with your image-level backups and you can restore images or files from this configuration, it might be time to think twice about tapes.
  2. Adding distance doesn't add time. Even when the images are moved off site to your cloud storage provider, file-level recovery will be nearly instant. Because your image-based backup solution should only request the blocks needed to recover the files you're asking for (instead of the complete backup job), and because nowadays downloads are faster than uploads, your recovery process should be nearly instantaneous. Think about how this compares to trying to locate a tape that was moved off site to fill the same request -- recovery could be days instead of minutes.
  3. Only pay for what you need to recover. Since image-based backup can restore files and images from a single image, you're going to save lots of bandwidth on cloud transfer and storage costs. Traditional backup products store files and images side-by-side, which results in more to recover and takes more of your money for bandwidth and storage.
  4. Time pressure is reduced. CSGs work on the principal that they have a local cache to allow data to come into the cloud storage gateway as fast as possible over the LAN before it's sent off to the cloud storage provider via the WAN. This is great because you're not compromising your image-based backup window to get your backup data into cloud storage.

  When I talk about the benefits of using the two technologies together I'm assuming that the VM backup software has the following capabilities that support efficient operations:

  • The ability to skip deleted data during backup. This is big. I recently did a test and found that skipping deleted data for 35 VMs with only Windows installs came out to a savings of 20 GB. That's 20 GB of data that doesn't need to be sent over the WAN to your cloud storage vendor and 20 GB that doesn't need to be paid for. Some cloud storage provides charge for both data transfer and storage, so skipping deleted data can mean a big savings.
  • Turning off compression during backup is also advantageous for minimizing file sizes. Most cloud storage gateways have their own de-duplication and compression features. If you've ever re-zipped a zip file you might have seen it get bigger. The same problem applies when cloud storage gateways de-dupe and compress previously compressed backups.
  • Enabling file-level restore from the backup image. If this process is done correctly, the backup software should only request the blocks needed to reassemble the requested files. In a CSG environment, the CSG will only request the necessary blocks from the cloud storage provider – as opposed to requesting the whole archive, whose size might be measured in gigs. File-level restores help keep transfer costs down and allow faster restores.

Like much about the cloud, CSGs are relatively new and subject to change. These are my initial observations and lessons learned about using image-based backup with cloud storage gateways; please share yours.

Posted by Jason Mattox on 02/03/2011 at 12:49 PM


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