[Samba] Need SMB server / client tuning help

Swapneel More swapmore15 at gmail.com
Thu Apr 6 21:37:41 UTC 2023


I am seeking your help to resolve a problem I am facing with the network
throughput of an SMB share.

We have two SMB shares: one containing files which are bigger in size and
the other containing a large number of small files. Both share sizes are in

While mapping the SMB share with large files on a Windows host and copying
files and directories, we observe a good network throughput of more than
300MB/s. However, when we map the other SMB share with a large number of
small files and attempt to copy files and directories, we experience a
significantly reduced network throughput of around 10MB/s.

Both SMB server and client are using SMB3 protocol.

The "EnableMultichannel" parameter has been configured to 'True' on the
Windows SMB client, but it is unclear how many channels will be created or
if multiple channels have been established between the SMB client and
server. A Wireshark dump on the SMB client side shows only eight
connections with single client and single server IP addresses. Although the
SMB client has only two NIC cards, the dump indicates only one IP address
for the client in the source address of the TCP connection. There is little
knowledge on optimizing multichannel and how many NICs are required on both
the SMB client and server to achieve optimal network throughput.
Additionally, the number of SMB/TCP connections needed between the SMB
client and server to transfer terabytes of data at a high throughput rate
remains unknown.

We have configured the following parameters on our Windows SMB client host.

PS C:\Users > Get-SmbClientConfiguration

ConnectionCountPerRssNetworkInterface : 8
DirectoryCacheEntriesMax                         : 4096
DirectoryCacheEntrySizeMax                     : 65536
DirectoryCacheLifetime                               : 60
DormantFileLimit                      : 1023
EnableBandwidthThrottling             : False
EnableByteRangeLockingOnReadOnlyFiles : True
EnableInsecureGuestLogons             : True
EnableLargeMtu                        : True
EnableLoadBalanceScaleOut              : True
EnableMultiChannel                    : True
EnableSecuritySignature               : True
ExtendedSessionTimeout                : 1000
FileInfoCacheEntriesMax               : 32768
FileInfoCacheLifetime                 : 60
FileNotFoundCacheEntriesMax           : 32768
FileNotFoundCacheLifetime             : 60
KeepConn                              : 600
MaxCmds                               : 32768
MaximumConnectionCountPerServer       : 64
OpLocksDisabled                       : False
RequireSecuritySignature              : False
SessionTimeout                        : 60
UseOpportunisticLocking               : True
WindowSizeThreshold                   : 1

PS C:\Users >

Any advice on the optimal SMB tuning parameters and their respective values
for both the SMB client and server sides would be highly appreciated. This
is necessary to address the issue at hand and to achieve optimal network
throughput on an SMB share that contains a large number of small files.
Please provide recommendations on any other settings that may be relevant
in this context.

Your assistance in this matter would be highly valued.

Thanks & regards,
Swapnil M.

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