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kumarkaushal-1277 asked SadiqhAhmed-MSFT commented

Question on Azure Site Recovery limits

I went through the below article where it clearly illustrates the below :

https://docs.microsoft.com/en-us/azure/site-recovery/azure-to-azure-troubleshoot-replication

Premium P20 or P30 or P40 or P50 disk 16 KB or greater 20 MB/s 1684 GB per disk

Change the tier of the disaster recovery storage disk: This option is possible only if the disk data churn is less than 20 MB/s. For example, a VM with a P10 disk has a data churn of greater than 8 MB/s but less than 10 MB/s. If the customer can use a P30 disk for target storage during protection, the problem can be solved. This solution is only possible for machines that are using Premium-Managed Disks. Follow these steps:

Go to Disks of the affected replicated machine and copy the replica disk name.
Go to this replica of the managed disk.
You might see a banner in Overview that says an SAS URL has been generated. Select this banner and cancel the export. Ignore this step if you don't see the banner.
As soon as the SAS URL is revoked, go to Configuration for the managed disk. Increase the size so that Site Recovery supports the observed churn rate on the source disk.


My question is :
If the Data disk writes bytes /sec is like 100 MB/s an average for p30 and data change rate is greater than 20 Mb/s .. What we will do in case ? Because the above solution only applies to p10 ,p20 disk with smaller size where we raise the size at the destination .

Is that i have to access the workload with the VM to find as to why such large change rate and that is only option ? How should i solve this problem .

Why i am asking this question :
I had 3 Vm's which had Recovery point generation failed and Data change rate beyond supported limits in the site recovery logs. 2 of the VM's has p10 disk and we took the call to raise the size at the destination . But the last VM has p30 disk .

azure-site-recovery
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@SadiqhAhmed-MSFT ... Any help with the above please ?

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Hi,

@SadiqhAhmed-MSFT

Can you advise if this has been implemented yet?

Thanks

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Could you please elaborate your ask?

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Appologies, I should have been more clear, I was just wondering if the "High Churn Support" feature is availiable yet?

I was querying your below comment:


SadiqhAhmed-MSFT avatar image SadiqhAhmed-MSFT kumarkaushal-1277 · Jul 02 2021 at 9:05 AM

@kumarkaushal-1277 We are working on a feature for higher churn support. I shall get back to you once it is in preview.
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SadiqhAhmed-MSFT answered kumarkaushal-1277 commented

@kumarkaushal-1277 If data change rate is greater than 20 mbps per disk, then that is not supported today.


If the response helped, do "Accept Answer" and up-vote it.

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@SadiqhAhmed-MSFT .. Thank you for your response. What can we do in that case if we are seeing that behavior with p30 disk ? Any inputs would be appreciated . Why i am asking this is i am seeing Recovery point generation failed and Data change rate beyond supported limits when their is a Crash consistent checkpoints being initiated and it just does not happen every time. The disk that it complains when we look at Data rate beyond supported limits is P30 disks.

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@kumarkaushal-1277 We are working on a feature for higher churn support. I shall get back to you once it is in preview.

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@SadiqhAhmed-MSFT .. thank you for the information

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You are welcome. Let me know if you have any further questions we can help with.

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ShahDarshanContractor-8585 avatar image
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ShahDarshanContractor-8585 answered

Hello,

I'm also facing same issue with SQL database VM.

I have enabled replication for VM. but since long time it is showing waiting for recovery point and not come to Protected state. Any hint or any workaround for this ?

• Replication Health Errors
• Error ID
153018
• Error Message
The data change rate (write bytes/sec) for server-disk-2 has exceeded ASR supported limits. This could be due to high I/O operations on disk caused by applications on the guest OS.
• Possible causes
The data change rate (observed for 60 mins) on the below disks of the virtual machine is more than the Azure Site Recovery supported limits for the target storage type. 1. server-disk-2, Churn rate : 20.37MBps, Observation start time : 01/25/2022 07:33:38 UTC, Churn rate limit : 20MBps
• Recommendation
1. Review the Azure Site Recovery supported limits at https://aka.ms/asr-a2a-target-limits. Ensure that the target storage type (Standard or Premium) is provisioned as per the churn rate requirement at source. 2. If you are already replicating to a premium disk, ensure that the size of disk supports the observed churn rate. Learn how to resize replica disk at https://aka.ms/increase-replica-disk-size 3. If the observed churn is temporary, wait for a few hours for the pending data upload to catch up and to create recovery points 4. Learn how to monitor churn activity while replication is in progress http://aka.ms/asr-a2a-churn-monitoring
• Related links
o https://aka.ms/asr-a2a-target-limits
o https://aka.ms/increase-replica-disk-size
o http://aka.ms/asr-a2a-churn-monitoring
• First Seen At
1/25/2022, 7:06:25 PM

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