Server Message Block: Difference between revisions

Revision as of 23:59, 29 February 2024

Revision as of 20:29, 15 March 2024

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Since the release of Windows 2000, the use of WINS for name resolution has been deprecated by Microsoft, with hierarchical [[Dynamic DNS]] now configured as the default name resolution protocol for all Windows operating systems. Resolution of (short) NetBIOS names by DNS requires that a DNS client expand short names, usually by appending a connection-specific DNS suffix to its DNS lookup queries. WINS can still be configured on clients as a secondary name resolution protocol for interoperability with legacy Windows environments and applications. Further, Microsoft DNS servers can forward name resolution requests to legacy WINS servers in order to support name resolution integration with legacy (pre-Windows 2000) environments that do not support DNS.

[[Network planning and design|Network designers]] have found that [[Network latency|latency]] has a significant impact on the performance of the SMB 1.0 protocol, that it performs more poorly than other protocols like [[File Transfer Protocol|FTP]]. Monitoring reveals a high degree of "chattiness" and a disregard of network latency between hosts.<ref name="barreto">{{cite web|author=Jose Barreto|date=December 9, 2008|title=SMB2, a Complete Redesign of the Main Remote File Protocol for Windows|url=http://blogs.technet.com/josebda/archive/2008/12/05/smb2-a-complete-redesign-of-the-main-remote-file-protocol-for-windows.aspx|access-date=November 1, 2009|publisher=[[Microsoft]] Server & Management Blogs|url-status=dead|archive-url=https://web.archive.org/web/20130112180513/http://blogs.technet.com/b/josebda/archive/2008/12/05/smb2-a-complete-redesign-of-the-main-remote-file-protocol-for-windows.aspx|archive-date=January 12, 2013}}</ref> For example, a [[Virtual private network|VPN]] connection over the [[Internet]] will often introduce network latency. Microsoft has explained that performance issues come about primarily because SMB 1.0 is a block-level rather than a [[Streaming algorithm|streaming]] protocol, that was originally designed for small [[local area network|LANs]]; it has a block size that is limited to 64K, SMB signing creates an additional overhead and the [[TCP tuning|TCP window size]] is not optimized for WAN links.<ref>{{cite web|author=Neil Carpenter|date=October 26, 2004|title=SMB/CIFS Performance Over WAN Links|url=https://docs.microsoft.com/en-us/archive/blogs/neilcar/smbcifs-performance-over-wan-links|url-status=live|archive-url=https://web.archive.org/web/20200213113816/https://docs.microsoft.com/en-us/archive/blogs/neilcar/smbcifs-performance-over-wan-links|archive-date=February 13, 2020|access-date=February 13, 2020|publisher=[[Microsoft]]}}</ref> Solutions to this problem include the updated SMB 2.0 protocol,<ref>{{cite web|title=What's New in SMB in Windows Server|url=https://technet.microsoft.com/en-us/library/hh831474(v=ws.11).aspx|url-status=live|archive-url=https://web.archive.org/web/20170211075409/https://technet.microsoft.com/en-us/library/hh831474(v=ws.11).aspx|archive-date=February 11, 2017|access-date=6 February 2017|website=Microsoft| date=31 August 2016 }}</ref> [[Offline Files]], [[TCP window scale option|TCP window scaling]] and [[WAN optimization]] devices from various network vendors that cache and optimize SMB 1.0<ref>{{cite web|author=Mark Rabinovich, Igor Gokhman|title=CIFS Acceleration Techniques|url=https://www.snia.org/sites/default/orig/sdc_archives/2009_presentations/monday/MarkRabinovich-IgorGokhman-CIFS_Acceleration_Techniques.pdf|access-date=July 6, 2020|publisher=Storage Developer Conference, SNIA, Santa Clara 2009}}</ref> and 2.0.<ref>{{cite web|author=Mark Rabinovich|title=Accelerating SMB2|url=https://www.snia.org/sites/default/orig/SDC2011/presentations/wednesday/MarkRabinovichAccelerating_SMB2.pdf|access-date=July 6, 2020|publisher=Storage Developer Conference, SNIA, Santa Clara 2011}}</ref>

== History ==

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SMB1 is an extremely chatty protocol, which is not such an issue on a [[local area network]] (LAN) with low latency. It becomes very slow on [[Wide area network|wide area networks]] (WAN) as the back and forth handshake of the protocol magnifies the inherent high latency of such a network. Later versions of the protocol reduced the high number of handshake exchanges. One approach to mitigating the inefficiencies in the protocol is to use [[WAN optimization]] products such as those provided by [[Riverbed Technology|Riverbed]], [[Silver Peak Systems|Silver Peak]], or [[Cisco Systems|Cisco]]. A better approach is to upgrade to a later version of SMB. This includes upgrading both NAS devices as well as Windows Server 2003. The most effective method to identify SMB1 traffic is with a network analyzer tool, such as [[Wireshark]]. Microsoft also provides an auditing tool in [[Windows Server 2016]] to track down devices that use SMB1.<ref name="messageanalyzer">{{cite web |last1=Kyttle |first1=Ralph |title=SMB1 – Audit Active Usage using Message Analyzer |url=https://blogs.technet.microsoft.com/ralphkyttle/2017/05/13/smb1-audit-active-usage-using-message-analyzer/ |website=Microsoft TechNet |publisher=Microsoft |access-date=28 March 2019 |date=13 May 2017 |archive-url=https://web.archive.org/web/20190328223802/https://blogs.technet.microsoft.com/ralphkyttle/2017/05/13/smb1-audit-active-usage-using-message-analyzer/ |archive-date=March 28, 2019 |url-status=live }}</ref>

Microsoft has marked SMB1 as [[deprecation|deprecated]] in June 2013.<ref>{{Cite web|title=The Deprecation of SMB1 – You should be planning to get rid of this old SMB dialect – Jose Barreto's Blog|url=https://blogs.technet.microsoft.com/josebda/2015/04/21/the-deprecation-of-smb1-you-should-be-planning-to-get-rid-of-this-old-smb-dialect/|url-status=live|archive-url=https://web.archive.org/web/20170521154946/https://blogs.technet.microsoft.com/josebda/2015/04/21/the-deprecation-of-smb1-you-should-be-planning-to-get-rid-of-this-old-smb-dialect/|archive-date=May 21, 2017|access-date=2019-10-09|website=blogs.technet.microsoft.com|date=21 April 2015 }}</ref> Windows Server 2016 and [[Windows 10 version 1709]] do not have SMB1 installed by default.<ref>{{Cite web|title=SMBv1 is not installed by default in Windows 10 Fall Creators Update and Windows Server, version 1709 and later versions|url=https://support.microsoft.com/en-us/help/4034314/smbv1-is-not-installed-by-default-in-windows|url-status=live|archive-url=https://web.archive.org/web/20191010052046/https://support.microsoft.com/en-us/help/4034314/smbv1-is-not-installed-by-default-in-windows|archive-date=October 10, 2019|access-date=2019-10-09|website=support.microsoft.com}}</ref>

=== CIFS ===

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=== SMB 3.0 ===

SMB 3.0 (previously named SMB 2.2)<ref name="smb3">{{cite web|url=https://cloudblogs.microsoft.com/windowsserver/2012/04/19/smb-2-2-is-now-smb-3-0/|work=Windows Server Blog|title=SMB 2.2 is now SMB 3.0|author=Jeffrey Snover|date=April 19, 2012|access-date=July 6, 2020}}</ref> was introduced with [[Windows 8]]<ref name="smb3"/> and [[Windows Server 2012]].<ref name="smb3"/> It brought several significant changes that are intended to add functionality and improve SMB2 performance,<ref>{{cite web | url=http://www.chelsio.com/chelsio-to-demonstrate-40g-smb-direct-rdma-over-ethernet-for-windows-server-2012/ | title=40G SMB Direct | author=Chelsio Communications | date=2 April 2013 | access-date=June 18, 2013 | archive-url=https://web.archive.org/web/20130907065805/http://www.chelsio.com/chelsio-to-demonstrate-40g-smb-direct-rdma-over-ethernet-for-windows-server-2012/ | archive-date=September 7, 2013 | url-status=live }}</ref> notably in virtualized [[data center]]s:

* the SMB Direct Protocol (SMB over [[remote direct memory access]] [RDMA])

* SMB Multichannel (multiple connections per SMB session),<ref>{{cite web | url=https://www.eiseverywhere.com/file_uploads/b4f7436c4bc86fe545abe9fc042d4a7f_JoseBarreto_SMB3_Remote_File_Protocol_revision.pdf | title=SNIA Tutorial on the SMB Protocol | author=Jose Barreto | date=October 19, 2012 | access-date=November 28, 2012 | publisher=[[Storage Networking Industry Association]] | archive-url=https://web.archive.org/web/20130603133014/https://www.eiseverywhere.com/file_uploads/b4f7436c4bc86fe545abe9fc042d4a7f_JoseBarreto_SMB3_Remote_File_Protocol_revision.pdf | archive-date=June 3, 2013 | url-status=live }}</ref><ref>{{ cite web | url=http://www.snia.org/sites/default/files2/SDC2011/presentations/keynote/ThomasPfenning_The_Future_of_File_Protocols-final.pdf | title=The Future of File Protocols: SMB 2.2 in the Datacenter |archive-url=https://web.archive.org/web/20120720020805/http://www.snia.org/sites/default/files2/SDC2011/presentations/keynote/ThomasPfenning_The_Future_of_File_Protocols-final.pdf |archive-date=2012-07-20 | author=Thomas Pfenning }}</ref>