Saving files to File Share is extremely slow

Dear ZsCaler community, Still not able to resolve my slow file access latency over smb2 issues. Has anyone experienced the same issue. Saving a file stored at smb network Share is extremely slow it takes upto 40seconds or more. it has been more 8 weeks now zscaler support not able to resolve this. Any help or guidance will be appreciated

Are you using smb2 or SMB3.1 as vs 3 has improvements for WAN.

Hi @FirstVoid we are using smb2. i will enable smb3 and retest it. i will post the results

Just out of curisity can you check your MTU size and the latency on the path where possible? If you have latency above 30ms then you will see huge impacts with SMB. If you test with a sharepoint (HTTPS) or onedrive you will see a huge diffrence. SMB has never been good over SMB. This is why companies like riverbed exist.

@FirstVoid Connection from my laptop to Zscaler connector is 30ms. SMB3 not impreved anything

Strange question, do you have any DLP client running next to ZCC ?
I only ask because we had fileshare slowness with 30kb files which was caused by our third party DLP solution. Might not be related but worth checking.

Hi @murat. Now do you have any solution ? I found the same problem like you. If you can sloved it, please help to share me.

I have managed to reduce slowness from 40sec-50sec. to 10-12sec. it was antivirus. But 12 sec still long still investigating

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What i suggest maybe you could also check on the diagnostics for the broker that is connected to between your user towards the broker and from your broker to your App connector it might be due to the broker connection might not be optimal which is why you may face this issue.

We having been facing this same issue, specifically with the Miami III DC and lasts ~1.5 hours. So only our Florida users are impacted. Client machines would lock up and saving files takes ages for such small files. Local ISP isn’t the issue as when ZPA is disabled and switched to an alternate remote access solution, problem is not there.

It has happened 4 times now - twice in March 2021, last week and just today. It doesn’t affect all users so it seems to be related to a specific cluster node.

We have a high priority ticket open on this already and provided logs but support is still not able to identify the root cause. The was a patch installed on the Miami ZEN back in March which was due to a memory leak. Not sure if there are still issues going on which are not identifiable.

It’s very frustrating since the issue cannot be identified and nothing is posted on the Trust portal indicating a possible issue.

For those experiencing the slowness issues, what DC/Broker are you connecting to when the issue is occurring?

I have similar issue : opening XLS files from file sharing is extremely slow.
users are based in Canada, using SMB v2 file sharing server.
same issue with mac and windows users.
tested with 2008R2 and 2016 servers with same results.
The connector is local ( in the same LAN as the file servers )
Do you think that putting in place a local broker can solve this issue ?

We are experiencing the same issue. Our users are connecting to several different European broker. In the best cases we have only a delay of about 6 seconds when saving an empty Excel file to a share. In our tests we compared the performance to a traditional vpn where the files took less than a second to save. We also saw slowness when we just renamed files on a share which took a couple of seconds with zpa and was instant with vpn.

We’ve provided all requested information, logs and packet captures to the support and are since waiting for an answer. We also asked if a private service edge could help with this issue but the support could not answer that.

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Hello Murat , could you please confirm if the issue is only related to XLS files ? or also XLSX ?
can you send me your ticket ID with Zscaler support ?

@Taieb. It is both extension. I am also running application .exe file which connects to database to returns a login prompt and takes up to 5 min.
ticket number are

Alright, thanks for these details.

We are looking at standing up a SMB file share in the Cloud through Azure.
At the current rate, this is very slow you are talking sub 200-300 KB/s.

Any suggestion on where to start - only a issue as it’s going through ZPA.

Hey John,

we use Azure Storage Sync Services via a dedicated Azure Windows VM as SMB provider and cache and Azure Storage as backend. All through ZPA. We got about 5-10 MB/s (40-80 Mbit/s) up and down. Right now it fully uitlizes my upload bandwith at home.

Do you use a similar setup?


Oddly - SMB access even SMB2 or SMB3 is quite slow. Even with the connector placed as close to the SMB share but could just be the way the protocol behaves. Any ideas any tweaks/adjustments we can make to improve the lag?

The solution/workaround we have put in place to enhance the performance is a private service edge ( local broker )

We have users in Peru and Columbia that are facing performance issues over ZPA. Sao Paolo, Brazil is the only the only DC (SAO4) / Public Service Edge (SA-BR) in South America.

I presume implementing the same solution/workaround of deploying a Private Service Edge on the west coast countries would help us too.