Please clarify my below concerns. If you can help me I would be happy.

Question

We have below VM size and has an OS disk with p40 is attached.

    Size::  Standard_D16s_v3  

vCPU: 16

Memory: GiB: 64

Temp storage (SSD) GiB: 128

Max data disks: 32

Max cached and temp storage throughput: IOPS/MBps (cache size in GiB): 32000/256 (400)

Max burst cached and temp storage throughput: IOPS/MBps2: 32000/800

Max uncached disk throughput: IOPS/MBps: 25600/384

Max burst uncached disk throughput: IOPS/MBps1: 32000/800

In microsoft document, it is saying that Dsv3-series VMs can burst their disk performance and get up to their bursting max for up to 30 minutes at a time.
For the below disk max burst duration is unlimited. We have enabled on demanding on disk

Premium SSD sizes :P40

Disk size in GiB: 2,048

Provisioned IOPS per disk: 7,500

Provisioned Throughput per disk: 250 MB/sec

Max burst IOPS per disk: 30,000*

Max burst throughput per disk: 1,000 MB/sec*

Max burst duration: Unlimited*

Eligible for reservation: Yes, up to one year

I referred some microsoft documents but my below doubts is not clarified from there. Could you please clarify my below doubts one by one.

1. How much time the disk will burst 30 minutes or unlimited?
2. what it mean by vm can burst disk performance upto 30 minutes?
3. what it mean by maximum burst duration of disk is unlimited?
4. After 30 minutes, what will happen to disk?
5. After 30 minute what will happen to the vm?
6. When will ondemanding for disk will start charge? After 30 minutes?
7. If disk burst unlimited, then will it affect the vm performance?
8. Is there any option for changing the burst duration of disk and vm

Answer 1

@Elisha George

I understand you have some questions about how disk bursting works with regards to the VM and disk. The article and link provided above are useful and I do recommend reading through them for a greater understanding.

Please note that bursting is meant to be a temporary thing and I would recommend relying on the baseline performance and monitoring your bursting metrics to make sure it is not fully depleted.

As you have already indicated you have two limits applied to your disks, the individual disk limit and the aggregate VM limit. Both of these will have bursting capabilities dependant on the VM and disk size. P40 disks can only burst if you have enabled on-demand bursting. Is this something that you have done? Otherwise, you cannot exceed the baseline for this single disk.

I will answer the below questions assuming you have enabled on-demand bursting and that you are only utilizing a single disk on the VM.

1. How much time the disk will burst 30 minutes or unlimited?
If you are under 25600 uncached IOPS you can burst unlimited. Once you surpass 25600 you will hit the 30-minute limit of the VM.

2. what it mean by vm can burst disk performance upto 30 minutes?
They can surpass the limit, 25600 uncached IOPS, for 30 mins and burst to 32000IOPS, 30,000 IOPS for your P40 disk configuration.

3. what it mean by maximum burst duration of disk is unlimited?
Meaning you can burst as long as you want when using on-demand, you just pay the cost associated with that. Covered in this section.

4. After 30 minutes, what will happen to disk?
Nothing, as long as you do not surpass the baseline IOPS of 25,600 uncached IOPS.

5. After 30 minute what will happen to the vm?
If you surpass the 25,600 uncached IOPS baseline you will no longer be able to burst and subject to that limit.

6. When will ondemanding for disk will start charge? After 30 minutes?
Billing information is highlighted in this section. You will be charged the flat fee as well as anytime the IOPS exceed the baseline. Please check the example for detailed information

7. If disk burst unlimited, then will it affect the vm performance?
No

8. Is there any option for changing the burst duration of disk and vm
No

Hope this helps!

-------------------------------

Please don’t forget to "Accept the answer" and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.