Does FSx Gatway transfer writes to AWS FSx immediately?


We are interested to use AWS FSx for Windows plus install FSx File Gateway at our main site. There will be multiple users using the File System, some from within the site and others will be accessing FSx directly from the internet. Our concern is whether a change made from a user on-site will be synchronized immediately and be visible to other users, or if there is a delay.

What is the minimum time does the FSx Gateway send its changes to the main AWS FSx? Is it near real-time, or more (like minutes)? Does a "write" stay on the FSx Gateway cache for a while or is it written immediately to the FSx?

Thanks in advance.

asked 6 months ago119 views
1 Answer

It depends on your network and bandwidth. You can monitor the CachePercentDirty CW metric to get an idea.


  • If the CachePercentDirty metric is 80 or greater, your file gateway is writing data faster to disk than it can upload the data to Amazon S3. Consider increasing the bandwidth for upload from your file gateway, adding one or more cache disks, or slowing down client writes.

  • If the CachePercentDirty metric is low, check the IoWaitPercent metric. If IoWaitPercent is greater than 10, your file gateway might be bottlenecked by the speed of the local cache disk. We recommend local solid state drive (SSD) disks for your cache, preferably NVM Express (NVMe). If such disks aren't available, try using multiple cache disks from separate physical disks for a performance improvement.***

You also should be aware of users writing/changing files on the FSx file system directly, and those changes being available on the gateway. This is the "Automated cache refresh settings" option. See: (THis is for Storage Gateway but the same concept applies for FSx)

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answered 6 months ago

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