Azure VM on Blob Storage Billing Question

Question

I heard that Azure Iaas VM uses Blob Storage to store the VHD. A few questions:

- Will we be charged by the Blob Storage capacity?

- Will we be charged by storage transaction each time we perform an access to Azure VM?

Answer 1

Hi,

Yes, You will be charged for the Storage Capacity you are using for storing your VHD files in Blobs.

Regarding the transactions,If your VM and the Storage accounts are present in the same datacentre you will not chaged.

following link may help you.

http://blogs.msdn.com/b/windowsazurestorage/archive/2010/07/09/understanding-windows-azure-storage-billing-bandwidth-transactions-and-capacity.aspx

one more forum question is closely related to yours. follow it to know more.

http://social.msdn.microsoft.com/Forums/en-US/windowsazuredata/thread/7dafd1d4-c915-404a-8fe6-6bb2de52bdda

---

I hope it helps!! If you found this post useful, Please "Mark as answer" or "Vote as Helpful". Thanks! VIJAY.

Answer 2

2 corrections/updates:

Yes, You will be charged for the Storage Capacity you are using for storing your VHD files in Blobs.

[Update] Since VHDs are stored as page blobs, you will only be charged for the data you're storing. Let's say you created a 30 GB VHD but storing only 1 GB of data in it, you will only be charged for 1 GB. All empty pages are not charged.

Regarding the transactions,If your VM and the Storage accounts are present in the same datacentre you will not chaged.

[Correction] This is incorrect. You're always charged for storage transactions. You're not charged for data egress if both your VM and storage accounts are in the same data center.

Answer 3

[Update] Since VHDs are stored as page blobs, you will only be charged for the data you're storing. Let's say you created a 30 GB VHD but storing only 1 GB of data in it, you will only be charged for 1 GB. All empty pages are not charged.

What happenned if my 30GB VHD full? Is it possible to increase it again WITHOUT any downtime?

If we are not charged for empty, why not we just always create the MAX size (say 1 TB)? Wouldn't it good as I don't have to worry about if it reach the size that I defined?

Answer 4

The default and MAX size of one Storage account is 1 TB . You cannot define manually the  

size manually. They grow as and when your storage capacity expands and there is no downtime while it expands.  This should be clear.

Answer 5

I don't think it is correct. To the best of my knowledge, Windows Azure does not support dynamic VHDs yet. I think once the VHD is used completely, you would need to transfer the data out to a bigger sized VHD manually.

One more thing, VHDs are stored as page blobs in Windows Azure Storage. Based on the documentation a page blob can be resized programmatically however if we do the same on a VHD, the VHD will become corrupted because the API does not know if the page blob is a VHD or not. When you request an increase in size, Storage API just adds bytes to the end of the page blob which messes up the 512 byte footer of the VHD.

Answer 6

Ok i get it. But VHD is a part of the storage and the MAx size is 1TB shouldn't it grow?

Whenever a VHD grows it should expand. I don't know if this is a design consideration not to expand?

But if so this has to be changed . I am sure we do't want to be called in middle of night asking dev guys to expand the storage when logs are failing to write.

Can you point to the documentation please? That would be helpful.

Answer 7

Please take a look at this blog post from Windows Azure Storage Team about supporting only fixed VHDs: http://blogs.msdn.com/b/windowsazurestorage/archive/2012/06/28/exploring-windows-azure-drives-disks-and-images.aspx

As far as Max size of 1 TB is concerned, I believe you can create an empty VHD of up to 1 TB in size and you will get billed only for the bytes you actually use in that VHD. This applies only to data disks. If the VHD is an OS Disk (i.e. hosting the operating system), then I believe the limit is 127 GB.

Hope this helps.