AWS – Making AWS FSx for Windows Highly Available through Multi AZ Resilience – Part 7: Costs and Considerations

Now that we have demonstrated fully implementing a highly available multi AZ FSx for Windows solution, this section will briefly review some of the costs that FSx can incur and also some considerations that should be kept in mind while implementing this solution in a production system.


As FSx is a fully managed solution provided by AWS, there is a premium cost attached, however depending on your desire to manage as little as possible within your infrastructure, it may be a premium thats highly worth paying. Our solution has 3 key cost areas; FSx for Windows, DFS Nameserver Instances (if you use on-premise servers, this may not apply to you) and also data transfer costs.

For our solution , we would have the following charges:

  • 2x FSx Cost (one per AZ)
  • 2x Instance Cost (one per AZ for namespace servers)
  • Data Transfer Costs – Replication traffic between filesystems
  • Data Transfer Costs – Outbound traffic

Its important to understand that by having “multi AZ” it is effectively doubling your costs in order to enable high availability and in turn piece of mind!

How to estimate FSx Costs

The cost for FSx for Windows is variable depending on your requirements for the solution, in the form of

  • Amount of provisioned data – Per GB/Month – This is how much data you intend your filesystem to be able to support, rather than how much data you are physically storing. For example, if you provision 500GB of storage, but only store 100GB of data, you still pay for the full 500GB you have provisioned.
  • Throughput required – Per MB/s Month – This is how quickly do you need to access your data, the throughput selected is PER filesystem (this throughput will have to be able to support all users accessing the filesystem).
  • Backup Storage – Per GB/Month – This is the amount of backup storage you require, its important to know that FSx uses a incremental backup strategy to ensure that you don’t have duplicated data.

For our multi AZ solution, both FSx systems will be identical copies within the same region so can assume the costs will be similar.

For example, if we provision 300GB of Storage with 8MBs of throughput and estimate 100GB of changes for our backup solution in London region, the cost would be:

  • Storage – $0.151 x 300 = $45.30
  • Throughput – $2.401 x 8 = $19.208
  • Backup – $0.053 x 100 = $5.30

Total Single FSx Cost: $69.81 per Month

Important Considerations

When looking at implementing FSx, some items that should be considered:

  1. How much data do you expect to grow too? – Provision for what you may use, not what you currently use as you may quickly outgrow your storage, and storage cannot be expanded on an existing filesystem
  2. How much throughput will all of your users need combined? – As with storage, provision for what you may use as you grow, throughput cannot be changed on an existing filesystem.
  3. Maintenance and backup schedules – You can configure maintenance windows for AWS to perform important tasks and maintenance on the filesystem. Pick times that have least impact on your usage of data. If you are using Multi AZ, make sure maintenance schedules don’t overlap to provide uninterrupted access to your data.
  4. Shadow Copies take up provisioned space. – If you have 300GB provisioned, and expect around 50GB to be used by shadow copies, you will only have 250GB of usable storage, plan accordingly.
  5. DFS Namespace Servers – Its important to size these instances appropriately for your end solution.
  6. Only make important data HA – As HA can double your FSx costs, if you need to keep costs low, ensure that you provision storage for important data and keep other data to a single AZ