How to lower latency of ultra SSD disk

Question

We have SQL database on a AzureVM. Issue is in the ultra SSD which is a data disk has disk Latency

We ran some database benchmarks.

The time to create a database takes around 90 seconds and the thread speed is around 115 seconds.

Same on a temporary Disk, that speeds are much faster. Around 20 seconds to create a Database and around 28 seconds Threads speed.

How we can reduce the latency of the disk?

Answer 1

@pedri
I understand you are wanting to improve the performance of your ultra disks, in particular the latency.

I think the first thing that needs to be determined is whether there is an IOPS or throughput bottleneck. To do this you can use the Storage IO utilization metrics. This should also run you through performance testing that can be done to determine the max capability of your disks and VM. Please note that VMs and disk have their own separate limits that need to be checked.

Ultra disks are the closest thing Azure offers currently to attached storage. If this does not meet your performance needs you will have to choose a VM with local storage.

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Answer 2

Hi @pedri ,

it seems the VM SKU doesn't offer the IOPS required for the Ultra Disk (IOPS 7500 and 130 MBPS):

https://learn.microsoft.com/en-us/azure/virtual-machines/dv3-dsv3-series#dsv3-series

As far as I know for this VM SKU the disk throughput (IOPS/MBps) is shared between all attached disks and not "per disk".
Some more information you will find here: https://learn.microsoft.com/en-us/azure/virtual-machines/disks-performance

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten