Slow Azure File Share Upload

AlphonseG 191

I have an Azure File share (large file shared disabled) via my MSDN subscription, that I've been using for several years now. I've always been able to see a constant upload speed of 70-90 mbps (via Task Manager network performance). Suddenly, I'm only getting 20-35 and very erratic, not constant.
Uploading to OneDrive, I see the 70.
Same for both uploads, on another (new) machine, so don't see it being my machine.
This is all the same whether I use the Azure portal upload feature or map a drive on my machine and drag/drop files.
I've tried creating additional file shares using various different settings (different locations, large file share enabled, etc.). Any improvement is marginal.
The Azure troubleshooting wizard has no suggestions.
How can I determine the cause of the slowdown, so I can look for a solution?

AlphonseG 191 Reputation points

2022-05-31T14:46:19.3+00:00

Update:
In Jan, I was finally able to set up a support case with Microsoft.
After 5 months, many sessions and many engineers/techs from different teams, they gave up.
Even though the issue does not occur with other cloud storage providers.
Their conclusion was "it had been an internal change, as there were no changes from your end and we are not notified of internal changes nor are we able to gather such information".
The only way to get around the issue is by using AzCopy or Microsoft Azure Storage Explorer, which itself uses AzCopy.
AzCopy gets around it by using multiple threads.

2 answers

Devaraj G 2,091 Reputation points

2021-12-19T02:50:44.493+00:00

Hi, Thanks for posting.

Performance bottleneck issues are tricky. Can cause form multiple angle. In Azure there is no separate throttling.
have you checked your speed using azure speed ? : https://www.azurespeed.com/Azure/Download

Something similar discussed here with good artefacts: Please have look.
https://learn.microsoft.com/en-us/answers/questions/621022/slow-upload-speed-azure-file-share-network-drive.html
Please sign in to rate this answer.
AlphonseG 191 Reputation points

2021-12-20T14:49:03.327+00:00

Thanks for the quick response. I had replied yesterday (had to wait for my upload to finish before running any tests), but apparently, my response got lost.
Download test is good 80-90 mbps. Upload, however, is only about 3.3 mbps.
Using AzCopy, however. I get 80-90 mbps upload.
So, it seems like the issue has to do with uploading via Windows Explorer (drag/drop, copy/paste, file copy via .Net code).
It had been working great for several years, then suddenly, a couple of weeks ago, slowed down. So, something has changed. Since I can duplicate on 2 machines (one is brand new), I'm thinking, it is either some Windows update, or Azure. Not sure what to do next.

Devaraj G 2,091 Reputation points

2021-12-21T01:28:59.063+00:00

Hi @AlphonseG , there could be multiple reason why the file explorer copy method is slow. endpoint,patch,antivirus,drivers etc.
I would recommend to use azcopy going forward to avoid any potential behavior bottleneck.

AlphonseG 191 Reputation points

2021-12-21T01:33:11.523+00:00

Thanks, I'd like to not resort to that, but may have to. It really bothers me that it's worked so well for so many years, then all of a sudden it doesn't.
Sign in to comment
Alan Kinane 16,791 Reputation points MVP

2021-12-20T14:55:12.913+00:00

Depending on how often you do these uploads and if it needs to be programmatic or not I would recommend using Azure storage explorer - https://azure.microsoft.com/en-us/features/storage-explorer/#overview

You should see much better performance with this application.
Please sign in to rate this answer.
Alan Kinane 16,791 Reputation points MVP

2021-12-20T10:20:52.84+00:00

Is this a standard tier Azure files share? If so, please bear in mind this is HDD based storage so you will not get consistent performance due to the nature of spinning disks. I would also recommend to enable large file shares. This will give you a higher maximum IOPS and throughput capacity.

It can also depend on the application that you are using to upload and what features that supports. This article will provide a number of useful troubleshooting tips: https://learn.microsoft.com/en-us/azure/storage/files/storage-troubleshooting-files-performance

AlphonseG 191 Reputation points

2021-12-20T15:20:12.56+00:00

Thanks for both responses.
Yes, it's standard tier, however, I've tried creating new shares with many various configurations, including tiers and always get the same results.
My main usage is via a little .NET app I built that uses file copy to transfer files. So, the Azure Storage Explorer won't do it. This has been working fine for several years, then suddenly, a couple of weeks ago, slowed down. So, something has changed.
Testing with AzCopy, I get 80-90 mbps upload. So, I think that would eliminate storage type and related issues.
It seems to have to do with the copy method. All of my other testing has been done manually.
Since I can duplicate on 2 machines (one is brand new), I'm thinking, it is either some Windows update, or Azure. I'll follow the link you provided later. Other than that, not sure what to do next.
Sign in to comment