Currently, the most interesting type of storage for the IT professional is Azure File storage. File storage in Azure refers to cloud-based Server Message Block (SMB) or Common Internet File System (CIFS) such as that provided by traditional Windows or Samba fileservers. Like an SMB share, an Azure Storage share can be used from multiple computers and by multiple users simultaneously. The difference is that the users don't have to be connected to the company network anymore.

Azure file shares are commonly used for so called lift-and-shift migrations, where the on-premises app is basically copied to the cloud as-is. This is often fast and easy, but not always the most cost-efficient solution. Other scenarios are shares for diagnostics or debugging data, shared application files, or simply temporary storage:

In the preceding diagram, the different logical levels of Azure file storage are shown. Directories and files are optional. Therefore, it's enough to create a share and connect to it, to start working with file storage. But there are also several downsides to the current file share implementation. Currently, there are only two important downsides to consider:

• Storage limit: In addition to the 500 TB per storage account and the limit of 200 storage accounts per subscription, there are also limits on file shares. The maximum size of a file share is 5 TB and the maximum size per file in a file share is 1 TB. On the other hand, there is no limitation on the number of files in total, if you stick to the file and file share size.
• Latency between location and Azure Storage: Because we are still talking about SMB traffic, and with that a protocol which is not WAN-optimized, we are struggling with latencies. Normally, you say every latency above 16 ms is not feasible for an SMB share. To solve that issue, you should consider using Azure File Sync and keep a file server in your location. 

The only ways to authenticate for file share access are access keys and shared access signatures (SAS). An SAS is basically a link that can be generated if someone needs limited access to a storage resource. They can be limited by time and storage service type (queue, table, blob, file). Basic permissions such as read, write, delete, and so on can also be defined when generating an SAS. An SAS should be used for untrusted external staff, temporary development test, or for customers for tests.

At the time of writing, Microsoft has started to work on a premium version of Azure file shares. The following table shows the most significant changes to standard file shares:

Access keys will be discussed in the next section.