[Samba] Need SMB server / client tuning help

[Peter Milesson]

On 06.04.2023 23:37, Swapneel More via samba wrote:
> Greetings!!
>
> 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
> terabytes.
>
> 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.
Hi Swapnil,

I guess this is the classic file copy performance problem. The OS 
overhead for storing a small file is the same as for a large file, 
particularly if there are classic hard disks involved. The hard disk 
mechanics sets physical limits for what is achievable. I had a look at 
the Hitachi Vantara HNAS specifications, and Samba isn't mentioned even 
once in that documentation. So your best bet is Hitachi support, or the 
Hitachi community forums.

Best regards,

Peter