SmsProxy.exe eating up all RAM during SMS file migration and crashing target server — how to tune buffer size ah?

Question

SmsProxy.exe eating up all RAM during SMS file migration and crashing target server — how to tune buffer size ah?

Hakim Ismail 20

Guys, need some advice here.

Currently doing a file server migration using SMS, but halfway through the copy phase, the SmsProxy.exe process on the destination node got massive memory leak.

The moment the sync job starts traversing deep directory trees, the RAM usage jumps straight to 100%, then the target server hangs/BSODs. Walaueh, cannot complete the cutover like this.

Anyone know how to manually throttle or tune the SMS transfer buffer size? Looking for a way to restrict the proxy memory allocation so it won't crash the box during deep-path transfers. Thanks in advance!

Best regards, Hakim.

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Answer 1

Hello @Hakim Ismail

I wouldn't try to tune an undocumented SmsProxy.exe transfer-buffer or memory-limit registry value. Microsoft doesn't document a supported Storage Migration Service setting for manually capping the proxy process's RAM usage.

What you're describing: SmsProxy.exe continuously consuming memory until the destination reaches 100% and eventually hangs/BSODs. This should be treated as an abnormal SMS Proxy condition, not normal transfer behavior.

First, make sure the orchestrator and destination server are fully patched. Microsoft notes that Storage Migration Service fixes are delivered through Windows Server cumulative updates, and the current troubleshooting guidance recommends checking OS compatibility and current servicing levels.

Then capture the SMS logs while reproducing the issue:

Get-WinEvent -LogName "Microsoft-Windows-StorageMigrationService-Proxy/Admin" |
    Export-Clixml C:\Temp\SMSProxy-Admin.xml
Get-WinEvent -LogName "Microsoft-Windows-StorageMigrationService-Proxy/Debug" |
    Export-Clixml C:\Temp\SMSProxy-Debug.xml

Microsoft specifically identifies these event channels for troubleshooting the destination proxy.

I'd also monitor the process during a controlled reproduction:

Get-Process Microsoft.StorageMigration.Proxy.Service |
    Select-Object Id,WorkingSet64,PrivateMemorySize64,VirtualMemorySize64

If memory increases continuously and isn't released as directories/files complete, stop the migration before the server becomes unstable and capture the relevant SMS Proxy events and, ideally, a process dump.

Microsoft's documentation also states that Windows Server 2019 and later destinations use the built-in SMS Proxy specifically for improved transfer performance.

I would not recommend arbitrary registry edits or attempting to throttle an undocumented SMS buffer. If the problem reproduces on a fully patched server, particularly with specific deep directory structures, this warrants Microsoft investigation as a potential SMS Proxy defect.

Please post the Windows Server version/build, SMS Proxy events around the memory spike, approximate file count, and whether RAM grows progressively or jumps immediately. That should help determine whether this is workload-related or an actual proxy memory leak.

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