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AlexandrosK-1323 asked SamWu-MSFT commented

SMB & IIS slow performance on load balance

Hi there,

We run 3 Windows 2019 servers. One of them acts as the SMB server, and the other 2 nodes have symlinks pointing to the SMB share. All of them are IIS servers.

Our application is PHP, and we're using Wincache for file system cache, and Opcache for opcode caching.

The problem is that, for the nodes that access the SMB share, the website is significantly slower. About 1 second slower.

All of the nodes have the same CPU/memory/SSD storage.

We verified that this is an SMB issue, by copying files for testing, to the other nodes, and indeed it was as fast as the main server (where the SMB share is located).

Searching around I found that Wincache is supposed to fix that, but it seems that still there's data going back and forth for the SMB share, making the website much slower compared to when the files are local.

Is this an SMB performance issue, or maybe a configuration issue?


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@AlexandrosK-1323 File server performance and available tunings depend on the SMB protocol that is negotiated between each client and the server, and on the deployed file server features. You can check which version of SMB is in use on your network by using Windows PowerShell Get-SMBConnection on clients and Get-SMBSession | FL on servers.

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Hi Sam,

Client: 3.1.1

Server returns something like this:

SessionId : 274945016605
ClientComputerName :
ClientUserName : HTTP-NODE2**
NumOpens : 1831
SecondsIdle : 0
SecondsExists : 41412

The servers are connected via multiple cat6 cables on LAN switch, and LAN teaming is also used. I get 2gbit speeds when copying large files.

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@AlexandrosK-1323 you can try to use latest SMB version.

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