Dealing with intermittent CIFS share disconnections can be particularly frustrating when your Windows Server 2008 R2 systems suddenly can't access a SAN-hosted share while all indicators suggest normal operation. The error message System.IO.IOException: The specified network name is no longer available appears when applications try to access files, though direct IP access remains functional.

Instead of rebooting the entire server, try restarting the Workstation service:

net stop workstation
net start workstation

This approach has proven effective in our environment where:

• Multiple app servers experience this issue independently
• SAN hardware shows no signs of stress
• Basic network connectivity remains intact

While the exact cause remains unclear, evidence points to potential SMB command queue exhaustion. The Windows Server 2008 R2 default setting for MaxCmds (50) might be insufficient for high-volume operations (~2500 ops/sec).

To check current connections and commands:

net statistics workstation

Consider increasing MaxCmds in the registry:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters]
"MaxCmds"=dword:00000100

Then restart the Workstation service. Note that values higher than 255 may cause issues.

When working with network shares in .NET, implement proper error handling and retry logic:

public byte[] GetFileWithRetry(string uncPath, int maxRetries = 3)
{
    int attempt = 0;
    while (true)
    {
        try
        {
            return File.ReadAllBytes(uncPath);
        }
        catch (IOException ex) when (ex.Message.Contains("network name is no longer available") && attempt < maxRetries)
        {
            attempt++;
            Thread.Sleep(1000 * attempt);
        }
    }
}

When hostname access fails, consider these alternatives:

1. Use IP-based UNC paths (\\192.168.1.100\share)
2. Map a persistent drive with proper reconnect flags
3. Implement a local cache for frequently accessed files

To catch these issues proactively:

• Set up performance counters for Workstation service
• Monitor Event ID 3019 in the System log
• Create a scheduled task to test share accessibility periodically

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When working with high-volume CIFS shares (especially in .NET applications serving numerous file operations), administrators occasionally encounter the frustrating error:

System.IO.IOException: The specified network name is no longer available

This typically manifests when:

• Application servers maintain sustained high connection rates (2500+ ops/sec in our case)
• Using both hostname (\\san-name) and IP address (\\x.x.x.x) access methods
• Windows Server 2008 R2 systems accessing EMC NX4 SAN storage

Restarting the Workstation service proves effective as a temporary solution:

net stop workstation /y
net start workstation

For PowerShell users:

Restart-Service -Name Workstation -Force

The issue stems from Windows' internal SMB command limit. The default MaxCmds registry value (typically 15) becomes insufficient under heavy loads. To check current settings:

reg query HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters /v MaxCmds

Increase the value to accommodate your workload (we recommend 50-100 for high-throughput scenarios):

reg add HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters /v MaxCmds /t REG_DWORD /d 50 /f

For PowerShell implementation:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters" -Name "MaxCmds" -Value 50 -Type DWord

To inspect current SMB connections before they fail:

net use

For detailed SMB session information:

Get-SmbConnection | Format-Table -AutoSize

When programming file access in .NET, implement retry logic:

public byte[] ReadFileWithRetry(string path, int maxRetries = 3)
{
    int attempt = 0;
    while (true)
    {
        try
        {
            return File.ReadAllBytes(path);
        }
        catch (IOException ex) when (ex.Message.Contains("network name is no longer available") && attempt < maxRetries)
        {
            attempt++;
            Thread.Sleep(1000 * attempt);
        }
    }
}

For deeper investigation:

# Check SMB client configuration
Get-SmbClientConfiguration | Select-Object -Property *

# View SMB session statistics
Get-SmbSession | Format-Table -AutoSize

# Monitor real-time SMB traffic
netsh trace start scenario=netconnection capture=yes tracefile=c:\temp\smbtrace.etl
# (Reproduce issue)
netsh trace stop

Consider implementing failover mechanisms in your code:

public string GetSanPath(bool useIp = false)
{
    return useIp ? @"\\192.168.1.100\share" : @"\\san-name\share";
}

// Usage with fallback
try 
{
    return ReadFile(GetSanPath());
}
catch (IOException)
{
    return ReadFile(GetSanPath(true));
}