NTFS volume cluster size will incur cost ?

Question

hi friend,

There are two data NTFS volumes, both of which are 16TB. One cluster is 4K, and the other is 8K. Do they incur the same cost? and does cluster size incur a cost?

Answer 1

@Huang, Winston-HR Welcome to Microsoft Q&A Forum, Thank you for posting your Query here!

It's not clear what you mean by "incur the same cost." If you're asking whether the two volumes will cost the same amount to use, then the answer is yes, assuming they are both using the same Azure storage account and access tier.

Regarding your question about cluster size, it does not directly incur a cost. However, the cluster size can affect the amount of space that is used by Azure File Sync metadata and heatstore, as well as the amount of free space that needs to be reserved on the local disk. In general, larger cluster sizes will require more space for metadata and heatstore, and will also require more free space on the local disk.

It's important to note that the cluster size can affect how efficiently space is utilized on the disk. In the context of NTFS, the cluster size determines the smallest amount of disk space that a file can occupy. Smaller cluster sizes can be more efficient for storing small files but may lead to more significant overhead for larger files, as they occupy whole clusters even if they don't fully utilize the space.

Based on your scenario: I would recommned to contact Azure Billing and Subscription team would be the best to provide more insight and guidance on this scenario: https://azure.microsoft.com/en-us/support/options/ it's free, and it's the best choice for you.

Please let us know if you have any further queries. I’m happy to assist you further.

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Answer 2

Hi @Huang, Winston-HR

Yes, different cluster size may incur different cost depending on the type of managed disk and the IO patterns of the workloads running in the VM. The reason for this is with certain managed disk types/configurations you are charged for transactions in addition to the disk size charge and outbound data transfer charges. A transaction is basically anything the VM does with the disk such as read/write/delete.

Depending on how IO is performed, smaller cluster size could result in more transactions, thus increasing cost. Without doing tests with your specific workload(s) you will not know if the difference is significant.

Please see pricing page below for details on transaction costs.

Managed Disks pricing

https://azure.microsoft.com/en-us/pricing/details/managed-disks/

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Thanks.

-TP