 Mathew George Sr. Software Engineer Microsoft Corporation ES23

North America EuropeAsiaSouth America Mean Std dev Min Max Continental Bandwidth (Mb/s) North America EuropeAsia Mean Std dev Min205 Max Continental Latencies (ms) Connectivity from branch offices to nearest data center, Fall 2007

Application Client Cache SMB Redirector Network SMB Server Server Cache Disk Filesystem Win32/NT File I/O APIs SMB Client Network Stack File Server

Application Client Cache SMB Redirector Network SMB Server Server Cache Disk Filesystem Win32/NT File I/O APIs SMB Client Network Stack File Server

Robocopy throughput comparison between Windows Server 2003 and Windows Server 2008 transferring a 4.5 GB file over a 1 Gbps WAN link. Pull = Copy from server to local disk Push = Copy from local disk to server

The effect of pipelining on network utilization IdleUtilized Non-pipelinedPipelined

CreateFile( GENERIC_READ | GENERIC_WRITE ) Granted batch oplock ReadFile CloseHandle ClientServer WriteFile Break Oplock Flush cached data CreateFile( GENERIC_READ ) WriteFile No more caching ! Create completes ReadFile completes. Data is cached. Close is not sent out on wire. CreateFile( GENERIC_READ | GENERIC_WRITE ) Cached handle is re-used. Data is written to cache. Cache is destroyed.

CreateFile( GENERIC_READ | GENERIC_WRITE ) Granted lease ReadFile CloseHandle ClientServer CreateFile( GENERIC_READ ) WriteFile Create completes ReadFile completes. Data is cached. Close is not sent out on wire. Cached handle is re-used. Data is written to cache. WriteFile

Windows 7 Server High latency Low-bandwidth WAN link Client 1Client 2 Windows 7 Clients First access to a file on the server pulls down the file over the slow WAN link (WAN access) Second access to the same file from another user in the branch is satisfied from the peer (local subnet access) Subsequent access from the same client is satisfied from the transparent cache (local machine access)

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