Merge pull request #57819 from SibonayK/patch-1

v4 cloud tiering changes

Author: PRMerger6

articles/storage/files/storage-sync-cloud-tiering.md

@@ -26,6 +26,8 @@ Azure File Sync does not support tiering files smaller than 64 KiB as the perfor
 ### How does cloud tiering work?
 The Azure File Sync system filter builds a "heatmap" of your namespace on each server endpoint. It monitors accesses (read and write operations) over time and then, based on both the frequency and recency of access, assigns a heat score to every file. A frequently accessed file that was recently opened will be considered hot, whereas a file that is barely touched and has not been accessed for some time will be considered cool. When the file volume on a server exceeds the volume free space threshold you set, it will tier the coolest files to Azure Files until your free space percentage is met.
 
+In versions 4.0 and above of the Azure File Sync agent, you can additionally specify a date policy on each server endpoint that will tier any files not accessed or modified within a specified number of days.
+
 <a id="afs-volume-free-space"></a>
 ### How does the volume free space tiering policy work?
 Volume free space is the amount of free space you wish to reserve on the volume on which a server endpoint is located. For example, if volume free space is set to 20% on a volume that has one server endpoint, up to 80% of the volume space will be occupied by the most recently accessed files, with any remaining files that do not fit into this space tiered up to Azure. Volume free space applies at the volume level rather than at the level of individual directories or sync groups. 
@@ -38,12 +40,22 @@ When a server endpoint is newly provisioned and connected to an Azure file share
 ### How is volume free space interpreted when I have multiple server endpoints on a volume?
 When there is more than one server endpoint on a volume, the effective volume free space threshold is the largest volume free space specified across any server endpoint on that volume. Files will be tiered according to their usage patterns regardless of which server endpoint to which they belong. For example, if you have two server endpoints on a volume, Endpoint1 and Endpoint2, where Endpoint1 has a volume free space threshold of 25% and Endpoint2 has a volume free space threshold of 50%, the volume free space threshold for both server endpoints will be 50%. 
 
+<a id="date-tiering-policy"></a>
+### How does the date tiering policy work in conjunction with the volume free space tiering policy? 
+When enabling cloud tiering on a server endpoint, you set a volume free space policy. It always takes precedence over any other policies, including the date policy. Optionally, you can enable a date policy for each server endpoint on that volume, meaning that only files accessed (that is, read or written to) within the range of days this policy describes will be kept local, with any staler files tiered. Keep in mind that the volume free space policy always takes precedence, and when there isn’t enough free space on the volume to retain as many days worth of files as described by the date policy, Azure File Sync will continue tiering the coldest files until the volume free space percentage is met.
+
+For example, say you have a date-based tiering policy of 60 days and a volume free space policy of 20%. If, after applying the date policy, there is less than 20% of free space on the volume, the volume free space policy will kick in and override the date policy. This will result in more files being tiered, such that the amount of data kept on the server may be reduced from 60 days of data to 45 days. Conversely, this policy will force the tiering of files that fall outside of your time range even if you have not hit your free space threshold – so a file that is 61 days old will be tiered even if your volume is empty.
+
 <a id="volume-free-space-guidelines"></a>
 ### How do I determine the appropriate amount of volume free space?
 The amount of data you should keep local is determined by a few factors: your bandwidth, your dataset's access pattern, and your budget. If you have a low-bandwidth connection, you may want to keep more of your data local to ensure there is minimal lag for your users. Otherwise, you can base it on the churn rate during a given period. For example, if you know that about 10% of your 1 TB dataset changes or is actively accessed each month, then you may want to keep 100 GB local so you are not frequently recalling files. If your volume is 2TB, then you will want to keep 5% (or 100 GB) local, meaning the remaining 95% is your volume free space percentage. However, we recommend that you add a buffer to account for periods of higher churn – in other words, starting with a lower volume free space percentage, and then adjusting it if needed later. 
 
 Keeping more data local means lower egress costs as fewer files will be recalled from Azure, but also requires you to maintain a larger amount of on-premises storage, which comes at its own cost. Once you have an instance of Azure File Sync deployed, you can look at your storage account’s egress to roughly gauge whether your volume free space settings are appropriate for your usage. Assuming the storage account contains only your Azure File Sync Cloud Endpoint (that is, your sync share), then high egress means that many files are being recalled from the cloud, and you should consider increasing your local cache.
 
+<a id="how-long-until-my-files-tier"></a>
+### I’ve added a new server endpoint. How long until my files on this server tier?
+In versions 4.0 and above of the Azure File Sync agent, once your files have been uploaded to the Azure file share, they will be tiered according to your policies as soon as the next tiering session runs, which happens once an hour. On older agents, tiering can take up to 24 hours to happen.
+
 <a id="is-my-file-tiered"></a>
 ### How can I tell whether a file has been tiered?
 There are several ways to check whether a file has been tiered to your Azure file share: