Clarification on Azure SMB file share transactions

I have previously written about the flexibility of Azure SMB file shares:

Creating an SMB file share

Azure SMB file shares – price and performance


Upon revisiting the Azure price calculator I now note there are three options when it comes to calculating operations costs on these file shares.

Each operation consists of units of 10,000 transactions. However, my questions was what actually constitutes a transaction? If I copy 10,001 files into an Azure SMB file share, is that 10,001 transactions or just one because it is a bulk operation?

So the answer (as I understand it) is that ANY file operation constitutes a transaction. For example, copy 10,001 file to Azure SMB file share = 10,001 transactions (cost = 2 operations = $ 0.0382 (put operation)). For example, do a directory listing of those 10,001 files once they have been copied to the Azure SMB file share = 10,001 transactions (cost = 2 operations = $ 0.0382 (list operation)). The only thing that won’t cost you a transaction is a delete operation.

With this in mind let’s try and cost out a generalised scenario. Let’s say you set up a 1TB Azure SMB file share for 50 users. That will cost you A$114.78 in storage. Now let’s say that your 50 users work on an average of 50 files a day. This means, your business is working with 2,500 files per day. Let’s now say that on average there are 4 transactions per file (list, open, put, list) per day. Thus, we now have an average of 10,000 transactions across your organisation for this Azure SMB file share per day. Thus, that means we get about 300,000 transactions per month on average. So this means we get 300,000 divided by 10,000 operations per month = 30. The total cost of these transactions over the month is then 30 x $ 0.0191 = A$0.57.

That means the cost of such an Azure SMB file share is: storage + operations = A$114.78 + (300,000/10,000) x A$0.0191 = A$114.78 + A$0.57 = A$115.35 per month. Remember, that this price also EXCLUDES any bandwidth costs to an on premises location.

That equates to about A$3.85 per month per user cost for such Azure SMB file storage.

The hardest thing about determining such pricing is clearly the number of operations (i.e. number of 10,000 transactions) that will take place on the data in the Azure SMB file share. However, what is important to remember here is that if you have a very active Azure SMB file share with lost of users ensure you need to keep a close eye on your operations (i.e. file transaction) costs because they can become quite expensive if you have lots and lots of them. For example, if we say we got 1,000 times more transactions a month (i.e. 300 million per month) that equates to 30,000 operations per month (i.e. 300,000,000/10,000), which is A$573 in transaction costs alone. Suddenly the Azure SMB file share option becomes a tad expensive. 

Azure SMB file shares are a great solution but like everything in Azure they may not be appropriate in all situations. In the case of high volume file transactions perhaps an Azure VM with a traditional file share would be more cost effective. Of course, there are other cost factors to consider with an Azure VM including the compute monthly cost, maintenance, etc. To provide a true comparison you need to ensure you consider all the relevant costs.

A future blog post will compare the costs of doing a file share from a traditional Azure VM so that you have a comparison to what’s been discussed here. So stay tuned for more on that real soon.

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