====== Samba - Faster Samba Performance ======

===== CPU =====

SMB is single-threaded.  This means SMB uses only one CPU core to transfer a file.

See:  https://www.samba.org/samba/docs/old/Samba3-Developers-Guide/architecture.html

Usually this is not a problem as SMB does not fully utilize a CPU core.  But on extremely busy systems this could overload your CPU core.

A better CPU, especially a multi-threaded one, will make a huge difference.

==== Bypass single-thread limitation ====

The single-thread limitation of SMB can be bypassed through opening multiple connections to your server.

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===== Samba Configuration =====

Samba’s default configuration is fairly poor.

Options which help speed up Samba:

<code smb>
[global]

# FORCE THE DISK SYSTEM TO ALLOCATE REAL STORAGE BLOCKS WHEN
# A FILE IS CREATED OR EXTENDED TO BE A GIVEN SIZE.
# THIS IS ONLY A GOOD OPTION FOR FILE SYSTEMS THAT SUPPORT
# UNWRITTEN EXTENTS LIKE XFS, EXT4, BTRFS, OCS2.
# IF YOU USE A FILE SYSTEM THAT DOES NOT SUPPORT UNWRITTEN
# EXTENTS, SET "strict allocate = no".
# NOTE: MAY WASTE DRIVE SPACE EVEN ON SUPPORTED FILE SYSTEMS
# SEE: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=798532

   strict allocate = Yes

# THIS IS TO COUNTERACT SPACE WASTAGE THAT CAN BE 
# CAUSED BY THE PREVIOUS OPTION 
# SEE: https://lists.samba.org/archive/samba-technical/2014-July/101304.html

   allocation roundup size = 4096

# ALLOW READS OF 65535 BYTES IN ONE PACKET.
# THIS TYPICALLY PROVIDES A MAJOR PERFORMANCE BENEFIT.

   read raw = Yes

# SERVER SIGNING SLOWS THINGS DOWN WHEN ENABLED.
# THIS WAS DISABLED BY DEFAULT PRIOR TO SAMBA 4.

   server signing = No

# SUPPORT RAW WRITE SMBs WHEN TRANSFERRING DATA FROM CLIENTS.

   write raw = Yes

# WHEN "strict locking = no", THE SERVER PERFORMS FILE LOCK
# CHECKS ONLY WHEN THE CLIENT EXPLICITLY ASKS FOR THEM.
# WELL-BEHAVED CLIENTS ALWAYS ASK FOR LOCK CHECKS WHEN IT IS
# IMPORTANT, SO IN THE VAST MAJORITY OF CASES,
# "strict locking = auto" OR "strict locking = no" IS ACCEPTABLE.

   strict locking = No

# TCP_NODELAY:
#    SEND AS MANY PACKETS AS NECESSARY TO KEEP DELAY LOW
# IPTOS_LOWDELAY:
#    [Linux IPv4 Tweak] MINIMIZE DELAYS FOR INTERACTIVE TRAFFIC
# SO_RCVBUF:
#    ENLARGE SYSTEM SOCKET RECEIVE BUFFER
# SO_SNDBUF:
#    ENLARGE SYSTEM SOCKET SEND BUFFER

   socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=131072 SO_SNDBUF=131072

# SMBWriteX CALLS GREATER THAN "min receivefile size" WILL BE
# PASSED DIRECTLY TO KERNEL recvfile/splice SYSTEM CALL.
# TO ENABLE POSIX LARGE WRITE SUPPORT (SMB/CIFS WRITES UP TO 16MB),
# THIS OPTION MUST BE NONZERO.
# THIS OPTION WILL HAVE NO EFFECT IF SET ON A SMB SIGNED CONNECTION.
# MAX VALUE = 128k

   min receivefile size = 16384

# USE THE MORE EFFICIENT sendfile() SYSTEM CALL FOR EXCLUSIVELY
# OPLOCKED FILES.
# NOTE: ONLY FOR CLIENTS HIGHER THAN WINDOWS 98/Me

   use sendfile = Yes

# READ FROM FILE ASYNCHRONOUSLY WHEN SIZE OF REQUEST IS BIGGER
# THAN THIS VALUE.
# NOTE: SAMBA MUST BE BUILT WITH ASYNCHRONOUS I/O SUPPORT

   aio read size = 16384

# WRITE TO FILE ASYNCHRONOUSLY WHEN SIZE OF REQUEST IS BIGGER
# THAN THIS VALUE
# NOTE: SAMBA MUST BE BUILT WITH ASYNCHRONOUS I/O SUPPORT

   aio write size = 16384
</code>

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===== References =====

https://wiki.samba.org/index.php/Performance_Tuning

https://wiki.samba.org/index.php/Linux_Performance

https://wiki.samba.org/index.php/Server-Side_Copy

https://www.samba.org/~ab/output/htmldocs/Samba3-HOWTO/speed.html

https://www.samba.org/samba/docs/current/man-html/smb.conf.5.html

https://lists.samba.org/archive/samba-technical/attachments/20140519/642160aa/attachment.pdf

https://www.samba.org/samba/docs/Samba-HOWTO-Collection.pdf 

https://codeinsecurity.wordpress.com/2020/05/18/setting-up-smb-multi-channel-between-freenas-or-any-bsd-linux-and-windows-for-20gbps-transfers/

https://www.snia.org/sites/default/files/SDC/2019/presentations/SMB/Metzmacher_Stefan_Samba_Async_VFS_Future.pdf

https://www.heise.de/newsticker/meldung/Samba-4-12-beschleunigt-Verschluesselung-und-Datentransfer-4677717.html