I’ve received quite a few questions from both new and experienced sysadmins about networked filesystems and file sharing protocols. One question that comes up frequently is “What is the difference between CIFS and SMB ?”
There are many idiosyncrasies, and the terminology can be confusing, so I’m going to boil down the essentials in an easy-to-follow blog post.
Here we go.
So what is SMB? SMB stands for “Server Message Block.” It’s a file sharing protocol that was invented by IBM and has been around since the mid-eighties. Since it’s a protocol (an agreed upon way of communicating between systems) and not a particular software application, if you’re troubleshooting, you’re looking for the application that is said to implement the SMB protocol.
The SMB protocol was designed to allow computers to read and write files to a remote host over a local area network (LAN). The directories on the remote hosts made available via SMB are called “shares.”
CIFS stands for “Common Internet File System.” CIFS is a dialect of SMB. That is, CIFS is a particular implementation of the Server Message Block protocol, created by Microsoft.
CIFS vs SMB
Most people, when they use either SMB or CIFS, are talking about the same exact thing. The two are interchangeable not only in a discussion but also in application – i.e., a client speaking CIFS can talk to a server speaking SMB and vice versa. Why? Because CIFS is a form of SMB.
While they are the same top level protocol, there are still differences in implementation and performance tuning (hence the different names). Protocol implementations like CIFS vs SMB often handle things like file locking, performance over LAN/WAN, and mass modification of file differently.
CIFS vs SMB: Which One Should I Use?
In this day and age, you should always use the acronym SMB.
I know what you’re thinking – “but if they’re essentially the same thing, why should I always use SMB?”
1.) The CIFS implementation of SMB is rarely used these days. Under the covers, most modern storage systems no longer use CIFS, they use SMB 2 or SMB 3. In the Windows world, SMB 2 has been the standard as of Windows Vista (2006) and SMB 3 is part of Windows 8 and Windows Server 2012.
2.) CIFS has a negative connotation amongst pedants. SMB 2 and SMB 3 are massive upgrades over the CIFS dialect, and storage architects who are near and dear to file sharing protocols don’t appreciate the misnomer. It’s kind of like calling an executive assistant a secretary.
Samba and NFS: Bonus Material
CIFS and SMB are far from the entirety of file sharing protocols and if you’re working to make legacy systems interoperate, it is quite likely that you’re also going to run into situations where others are necessary. Two other prominent file sharing protocols you should know about are Samba and NFS.
What is Samba? Samba is a collection of different applications with when used together let a Linux server perform network actions like file serving, authentication/authorization, name resolution and print services.
Like CIFS, Samba implements the SMB protocol which is what allows Windows clients to transparently access Linux directories, printers and files on a Samba server (just as if they were talking to a Windows server).
Crucially, Samba allows for a Linux server to act as a Domain Controller. By doing so, user credentials on the Windows domain can be used instead of needing to be recreated and then manually kept in sync on the Linux server.
The acronym NFS means “Network File System.” The NFS protocol was developed by Sun Microsystems and serves essentially the same purpose as SMB (i.e., to access files systems over a network as if they were local), but is entirely incompatible with CIFS/SMB. This means that NFS clients can’t speak directly to SMB servers.
So what does NFS mean in terms of your network communications toolkit? You should use NFS for dedicated Linux Client to Linux Server connections. For mixed Windows / Linux environments use Samba.
Practical Next Steps
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Other CIFS and SMB Resources
- Why You Should Never Again Utter the Word, “CIFS”
- Wikipedia: Server Message Block (SMB)
- Wikipedia: Networked File System (NFS)
- List of Products that Support SMB
- The Official Samba 4 How-To
- Windows NFS Performance vs. Windows File Sharing
- Best File Sharing Protocol for Windows clients?