Exchange 2013 - outlook in LAN environment very slow upload but fast download - not using 'use cached exchange mode'

Hi,

I have Exchange 2013 setup in a new environment (no migration) and it is working great except I just realized there is a big problem.

I notice the following

Problem 1:

Outlook 2010 with sp2 with cached exchange mode on: when I import the pst into outlook, it imports fine but the sync is extremely slow. It uploads to the Exchange 2013 mail server at 20-70KB/sec (bytes) via LAN.

Problem 2:

Outlook 2010 with sp2 with cached exchange mode off: when I import the pst into outlook, it imports extremely slow. It uploads to the Exchange 2013 mail server at 20-70KB/sec (bytes) via LAN.

More info:

-user1 has 1GB of mail and when setting up the user on a new pc with outlook with cached exchange mode on, it downloads the mail very fast. It downloads at 40-80 Mbps/sec (bits).

-I have Exchange 2013 with CU3 with win2k12 non r2.

Why is the download so fast from Exchange 2013 but the upload to Exchange 2013 is extremely slow? How do I fix this?

Thanks

June 11th, 2014 2:08am

Hi

Why don't you import pst files from the server rather than doing it across the network? If you importing mail it will be slow as the DB is busy, if you doing this for multiple users it will be even slower.

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June 11th, 2014 11:11am

Hi DareDevil57,

I just updated from Exchange 2013 CU3 to CU5 and issue remains.

There is another serious problem that needs to be addressed. I also notice that when sending an email with an attachment, it's insanely slow for it to sync up with the mail server as well.

For example with cache exchange mode via LAN or non cached mode via LAN, if I create a new email and attach a 10MB PDF file and click on send, it goes to outbox and then it goes to sent items. Then it syncs up with the mail server at 1Mbps or less a second.

How do I fix this slow connection issue?

I also did another test. I notice that when I use exchange non cached mode, and I export the mailbox to PST, it exports at 1Mbps or less a second.

Something is definitely not working properly and this is is a new setup. How do I troubleshoot this slowness issue? The PC and server are connect via LAN 1Gbps switch. I did a file transfer test via windows file sharing and I can download and upload blazing fast.

June 11th, 2014 3:05pm

Hi,

Bandwidth is not the only factor causing this problem, the hardware performance may also affect.

Disk I/O is an important factor when you uploads the email to exchange server.

I recommend you use performance monitor to check if there is any performance issue when uploading.

Thanks.

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June 12th, 2014 10:10am

Hi Niko,

I have checked the hardware and there are no problems at all.

The Outlook LAN client can only upload to Exchange at 1Mbps or less but when setting up a new Outlook LAN client for cached exchange mode, it can download at 40-80Mbps.

It seems like there is a bug or maybe something is throttling exchange. How do I check this?

I just did another test and importing a 54MB file in Outlook into Exchange without cached mode took 20minutes. Outlook was uploading to Exchange at 50KB (bytes)/sec on avg.

How do I identify the cause of the slow upload? I tested this with Outlook 2010 and 2013 and upload was slow in both. I believe the issue is related to Exchange 2013.

Thanks



  • Edited by kungpow112 Thursday, June 12, 2014 2:29 PM
June 12th, 2014 2:03pm

I just did another test.

I used OWA via LAN and created a draft email and attached a 10MB file and it uploaded instantly at 72Mbps/sec (bits). When doing the same in Outlook, it uploads at 50KB/sec (bytes).

Looks like I have isolated the issue to Outlook 2010/2013. Looks like there is a bug between Outlook 2010/2013 and Exchange 2013. I have not tested Outlook 2007.

How do I fix this slow upload issue in Outlook? Everyone on the LAN with Outlook is having the same issue.

Thanks



  • Edited by kungpow112 Thursday, June 12, 2014 3:04 PM
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June 12th, 2014 3:01pm

Here's another test that I just did.

I just setup another new server with win2k12 non-r2 with exchange 2013 and outlook only uploads at around 50KB/sec (bytes) to exchange as well.

For the outlook test, outlook was setup with cached exchange mode via LAN and I created a draft email with 10MB attachment and it took around 3-5mins for the sync to complete.

How do I fix this slow upload issue?

Thanks

  • Edited by kungpow112 Friday, June 13, 2014 7:17 AM
June 13th, 2014 7:13am

Does anyone else have this problem? How do I fix this?

Thanks

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June 23rd, 2014 3:01pm

kungpow112 -

I too am experiencing the same issue and have not yet found a fix.  Have you made any progress on your issue?

My Environment:
Outlook 2010 SP2 on Server 2008 R2 RDS
Exchange 2013 CU5 on Server 2012 R2
VMware ESXi 5.5 environment

July 31st, 2014 8:40am

ISO-Michael,

My environment is similar to yours. I have not found a fix yet.

Environment:
Outlook 2010 SP2 with win7 pro 64bit sp1
Exchange 2013 CU3 on win2k12 standard non r2 domain controller (VMware ESXi 5.5.0 Free Edition)
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July 31st, 2014 4:50pm

Which VMware network card are you using?

Do you have IPv6 Enabled on your Exchange server?  Have you tried disabling it?

Which specific build of VMware are you running?  I'm at 1746018 (but I know that isn't the latest and I'm working on getting it patched.)

July 31st, 2014 9:00pm

ISO-Michael,

For VMware network card, I am using VMXNET3. The E1000 NIC which is selected by default when creating a virtual machine doesnt work well in win2k12. I notice random disconnects. I see the link down and link up event messages in Event Viewer. I dont see these messages with VMXNET3.

VMware ESXi version, I am on 5.5.0 Build 1331820.
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July 31st, 2014 11:01pm

kungpow112,

I have opened a case with Microsoft on this and I'm working with an engineer now on the issue.  I'll post again when I have more information.

July 31st, 2014 11:18pm

Festivalman pointed me to another Technet forum post: http://social.technet.microsoft.com/Forums/office/en-US/0d45b1b0-3047-4666-ad04-217e98ed8823/slow-online-mode-browsing?forum=exchangesvrclients which is more of a hack than a true fix, but it does fix the issue in the eyes of the users.

In further testing, with Exchange 2013 on Server 2012 R2, the issue doesn't occur on an RDS Server running Server 2012 R2 or Windows 8.1.  I have not yet tested the scenario with Exchange 2013 on a different version of Windows, but I have plans to do so in the near future.

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August 5th, 2014 2:53pm

ISO-Michael,

Did the registry hack fix it for you? Did Microsoft identify the cause and provide a solution?

"In further testing, with Exchange 2013 on Server 2012 R2, the issue doesn't occur on an RDS Server running Server 2012 R2 or Windows 8.1"
-So this happens to you too with windows 7 with outlook 2010?

Thanks
  • Edited by kungpow112 Tuesday, August 05, 2014 4:32 PM
August 5th, 2014 4:30pm

kungpow112,

I was able to replicate the same issue under Windows 7 and Office 2010; however, my users on those platforms use cached mode.  I applied the registry hack on my Terminal Server (Server 2008 R2) and it did solve the issue.  I didn't test on the Windows 7 computer, but I'd expect that it would solve the issue there as well.

The registry hack is applied on the client computer, not the server.  In my case, the "client" computer is a server operating system since it is an RDS environment.

Let me know if you have any questions.

-- Michael

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August 5th, 2014 4:35pm

ISO-Michael,

I haven't tried the registry hack yet but do you have these problems as well?

"I was able to replicate the same issue under Windows 7 and Office 2010; however, my users on those platforms use cached mode."
-I am using cached mode as well but you can still see that it is slow in cached mode by creating say an email with a 20MB attachment. The user doesn't care that it is stuck in the Outbox as eventually it will go out and Outlook is not slow for the user. However, it does get stuck in the outbox for a very long time uploading to the mail server at a very slow speed.

The bigger problem is when you need to import say a 500MB pst into Outlook cached mode. It imports fine but after import you have to leave Outlook on for 24-48hrs for it to sync up the 500MB with Exchange.

Thanks

  • Edited by kungpow112 Tuesday, August 05, 2014 5:47 PM
August 5th, 2014 5:46pm

I did some more testing.

I setup a test environment with:
-Exchange 2013 SP1 on win2k12 r2
-Outlook 2010 SP2 on windows 7 sp1
-Outlook 2010 SP2 on windows 8.1
-Outlook 2013 SP1 on windows 8.1

Both windows 7 and windows 8.1 have the very slow upload issue to Exchange 2013. Windows 7 upload to Exchange 2013 is around 20-70KB/sec (bytes) via LAN. Windows 8.1 upload is a bit more responsive at around 500-600KB/sec (bytes) via LAN.

I changed the TcpAckFrequency to 1 for windows 7 and 8.1 and the problem went away. The upload on both Windows 7 and 8.1 was going at megabytes after the change.

I hope Microsoft fixes this soon.


PowerShell script to have this automated via GPO:
http://community.spiceworks.com/topic/571571-outlook-slow-after-migrating-to-exchange-2013

PowerShell Script:
$strGUIDS=[array](Get-WmiObject win32_networkadapter -filter "netconnectionstatus = 2" | select -expand GUID)
foreach ($strGUID in $strGUIDS) {New-ItemProperty -path HKLM:\System\CurrentControlSet\services\Tcpip\Parameters\Interfaces\$strGUID -propertytype DWORD -name TcpAckFrequency -value 1}




  • Edited by kungpow112 Monday, September 29, 2014 7:10 AM
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September 29th, 2014 6:58am

I just did another test.

Outlook 2013 SP1 32bit on windows 8.1 Pro with the latest updates (Oct 2, 2014) for both the OS and Office and still having the same issue with slow upload to Exchange 2013.

Looks like the registry key TcpAckFrequency has to be used for now until Microsoft comes up with a fix.
October 2nd, 2014 7:03am

Also tested Exchange 2013 slow upload with
-XP SP3 with Outlook 2007 SP3
-XP SP3 with OUtlook 2010 SP2

They have the slow upload issue as well and need the TcpAckFrequency registry key.
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October 5th, 2014 9:14pm

Looks like I have pinpointed the issue.

Exchange 2013 SP1 on win2k12 r2 on a physical server: no slow upload issue.

Exchange 2013 SP1 on win2k12 r2 on VMware ESXi 5.5 U2: has slow upload issue.
-tried E100E & VMXNET3 network adapters, doesn't fix the issue.
-only way to fix the slow upload issue is to modify the registry key TcpAckFrequency on the PC
October 6th, 2014 7:18am

Hi Kumgpow112

thank you for sharing that update. Please let us know if you need any further help. Perhaps try getting hold of the guys that do VMWARE and ask for help. Are the drivers up to date? any newer integration components?

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October 6th, 2014 7:21am

I have found another solution. Instead of modifying the registry key TcpAckFrequency on each PC, you can downgrade VMware Tools to an earlier version.

I have ESXi server running on 5.5 U2 and the Exchange 2013 guest OS is running VMware Tools 5.5 U2. After downgrading the VMware Tools from 5.5 U2 to 5.1 U1, it fixes the TcpAckFrequency issue.

To download an older version of VMware Tools:
http://packages.vmware.com/tools/esx/index.html
  • Edited by kungpow112 Sunday, October 19, 2014 1:58 AM
October 19th, 2014 1:58am

Another solution:

The slow upload issue hasn't been fixed in ESXi 6.0.0.

I have tested this on Exchange 2013 CU9 with win2k12 r2 on ESXi 6.0.0 and removing the following vmware tools features fixes the slow upload issue:
NSX File Introspection Driver
NSX Network Introspection Driver
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September 13th, 2015 2:35am

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