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URL: https://techcommunity.microsoft.com/blog/azurestorageblog/cost-saving-with-standard-ssd-billing-caps/3758792

⇱ Azure Disks Standard SSD billable transaction cap blog


Blog Post

Azure Storage Blog
4 MIN READ

Cost saving with Standard SSD Billing Caps

As part of our commitment to continuously delivering increased value for our Azure Disk Storage customers, we are excited to introduce a cap on the number of billable Azure Standard SSD transactions. As a result, we have made changes to the billable transaction costs per hour that can result in additional cost savings.  

The total cost of Azure Standard SSD Disk Storage depends on the size, number of disks, and the number of transactions. The number of transactions a disk can execute/perform/process is unchanged, so your disk will work as it always has been. However, the cost associated with these transactions is now limited and can help avoid greater costs. 

The table below contains the maximum number of billable transactions for Standard SSD Disk Storage:

Product

LRS Transaction Cap (# of Trx / hr)

ZRS Transaction Cap (# of Trx / hr)

E1

6,800

7,800

E2

13,400

15,400

E3

26,600

30,600

E4

43,400

61,000

E6

81,200

114,400

E10

147,200

214,000

E15

274,000

398,400

E20

502,000

737,600

E30

829,200

1,238,800

E40

893,000

1,344,700

E50

1,578,400

2,405,600

E60

2,777,500

4,243,900

E70

4,379,300

7,353,100

E80

9,478,400

14,706,200

If the number of hourly transactions listed on the table is reached, you will not incur additional transaction costs. The new pricing is effective March 6th, 2023 and applies to all the regions where Standard SSD is currently available.  There is no action needed by users to use these billable caps, as they are enabled by default on all existing and new Standard SSD Azure Disks. These billable caps apply to all Standard SSD disks, including those being used as OS or data disks.Let’s review a few important details associated with this announcement. 

On Azure, input/output operation per second (IOPS) and transactions are similar with one major exception:

A transaction on Azure is an I/O operation less than or equal to 256 KiBs of throughput. If your IO operation is larger than 256 KiBs of throughput, it is considered to require multiple transactions. The number of transactions is calculated by dividing the I/O size by 256 KiBs. 

For example, an IO with the size of 1024 KiBs (1MiB) would be processed as 4 transactions on a Standard SSD disk.

Let's look at an example to see how the new billing cap can help you save money. If you’re using an E4 disk with a block size of 4KiBs that averages 100 IOPS per month. With this block size 1 IO equals 1 transaction. 

Previously without the transaction cap, the 100 transactions/second would have resulted in the following billable transactions:

100 transactions/sec * 60 seconds * 60 minutes/hour = 360,000 Billable transactions
That would have resulted in the hourly cost shown below:
360,000billabletransactions$0.002/10,000Transactions=$0.072perhour
And having that cost over a month would be:
.072*730 hours/month = $52.56 per month

Therefore, without this newly announced transaction cap, you would have been billed around $52 per month for an E4 SSD disk performing an average of 100 IOPS (transactions) for the transaction activity.

Now with the E4 disks having an hourly billable transaction cap of 43,400 transactions in an hour, your hourly bill with a Disk running at 100 IOPs would be:

43,400billabletransactions$0.002/10,000Transactions=$0.0087perhour
And having that cost over a month would be:
$.0087730hours/month=$6.33permonth
And your monthly billing statement would add up to a grand total of $6.33. That’s an 88% reduction in transaction costs based on this example.

Following the same example, let’s evaluate the cost of Standard HDD, which is cheaper per transaction than Standard SSD but does not have a cap on billable transactions:

360,000 billable transactions∗ $0.0005/10,000 Transactions∗ 730 hours/month=$13.31 per month

Your monthly Standard HDD transaction bill would add up to $13.31. That’s more than double the transaction bill would have been with cost you would incur by deploying a Standard SSD disk of the same capacity. 

In addition to the potential cost savings, upgrading from Standard HDD to Standard SSD has the following advantages:

  • Increased service-level availability (SLA) of single-instance VM connectivity from 95 percent to 99.5 percent, improving availability guarantees.
  • Reduced latency by 2X, making data retrieval faster while increasing application performance.
  • Improved consistency of performance in terms of input/output operations and throughput, making your applications run more smoothly.
Updated Jan 10, 2024
Version 2.0