NFS versus CIFS for Intensive Filesystem Sharing/Serving Amongst UNIX servers

[Alzhy]

I had posts earlier regaring NFS and CIFS. I thought why not start a thread to get the feel for the virtues and suitability of using NFS or CIFS for filesystems sharing/serving between UNIX servers.

We have a "legacy perception" problem that dates back to something like 5+ years ago that basically favoured CIFS over NFS on HP-UX environments.

What say you and can you please share your rationale for picking one over the other.

Points will be awarded accordingly.

[Arunvijai_4 · Accepted solution]

Hi Nelson,

NFS is prefered over CIFS when it is between UNIX machines. NFS is the first protocol designed for file sharing across the network when UNIX invented.

CIFS is suitable for Unix and Windows file sharing. NFS has the proven ability when it comes to performance.

-Arun

[Arunvijai_4]

Hi Nelson,

Just googled and got interesting links,

http://forums.designtechnica.com/archive/index.php/t-5132.html
http://searchstorage.techtarget.com/expert/KnowledgebaseAnswer/0,289625,sid5_gci1113518_tax289166,00.html
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLJ,GGLJ:2006-08,GGLJ:en&q=NFS+vs+CIFS

-Arun

[eric roseme]

Hi Nelson,

The CIFS Client was originally developed (ported) to HP-UX in response to a particular multi-national customer requirement. They needed to do extensive client-server file sharing over a WAN across multiple continents. This was before NFS TCP on HP-UX. In addition, they required Windows server access from HP-UX. So the CIFS Client was a great solution (TCP session over WAN).

So I would say that the CIFS Client was never intended to supplant NFS UDP/TCP in a data center LAN. Now that we have NFS over TCP, UNIX-UNIX file sharing over a WAN can also be reliably served by NFS. I work with Dave Olker in the HP networking lab ATC (Dave does NFS, I do CIFS), and we agree that NFS is usually the better solution for UNIX-UNIX, and CIFS (server or client) is better for UNIX-Windows.

Eric Roseme

[Alzhy]

Eric Many Thanks!

Would your views on NFS as more appropriate UNIX to UNIX filesystem sharing apply to NFS v3 as well? We are still using 11.11 and cannot go to 11i version 2+ which offers NFS v4 which is reportedly out already and better.

[eric roseme]

Dave is the expert on NFS, but I can safely say that if you can use V3, then do so. I just checked the PV2-PV3 chapter in his book (to CMA), and the last line is "The recommendation is to use NFS PV3 whenever possible."

PV4 is not available on HP-UX at this time, but it is under development. I doubt that it will ever be rolled back to 11i. I know that we are looking for PV4 beta customers on 11.31 only, though (in case you are interested in trying 11.31).

Eric Roseme

[Steven E. Protter]

Shalom,

Version 4 of NFS is available for 11i v2, at least last time I checked with software.hp.com

If its not available at all, its 20 months late according to what I heard.

Don't worry about the legacy perception. NFS does a fine job in many situations and its used on many NAS devices. NFS with TCP should be stable and there is nothing wrong with using it.

There are possible security implications as NFS does not encrypt the actual data its sending back and forth.

SEP

[Dave Olker]

Shalom Stephen,

NFS V4 is not available on HP-UX 11i v2. I wish it were, but it's not. NFS V4 will arrive in 11i v3. Please tell me where on software.hp.com you found a reference to NFS V4 on 11i v2 so that I can get it removed.

NFS V4 *was* originally slated to arrive in 11i v2, along with a completely re-written version of NFS V2/V3 using a much newer code base from Sun. However, that was before the decision was made to completely revamp 11i v2 and get it working on both IA/PA systems.

When the decision was made to add PA support to 11i v2, many features (not just the newer NFS V2/V3 and the introduction of NFS V4) were moved to 11i v3 in order to meet the aggresive 11i v2 IA/PA delivery schedule. This was unfortunate for NFS, but it was the right decision for HP.

Trust me, when HP-UX supports NFS V4 I'll be the first one shouting it from the rooftops.

Regards,

Dave

[Alzhy]

So David,

Which one would you actually suggest we use? We're talking here about UNIX to UNIX Fileserving/Sharing only -- no Windows Server involved at all.

Will I be better off using CIFS (which supposedly is fixed under A.02.01 ?) or stick with what's been the native filesharing protocol of Unices since the epoch?

[Dave Olker]

Nelson,

You're asking an NFS wonk to choose between NFS and CIFS? Would you really trust my answer as being unbiased? :)

For Unix-to-Unix my recommendation is always to use NFS.

I've never been comfortable with the idea of a CIFS client that basically piggy-backs on the NFS client code to do it's work. Too many opportunities for problems - i.e. if you hit an NFS client problem it will masquerade as a CIFS client problem, so how do you know which to fix? Also, if the NFS client is configured poorly for performance it can negatively affect your CIFS client peformance. Again, I just don't care for that design.

If both sides are either UNIX or Linux, my recommendation would be to use NFS. When Windows clients enter the picture then I'd start looking at CIFS for the server side. However, I also know of many customers who run NFS clients on their Windows systems in order to use the same protocol as their UNIX/Linux systems. To each his own.

Regards,

Dave

[Dave Olker]

I just realized I spelled Steven Protter's name wrong in my previous post. I apologize Steven. I should just stick to using SEP. :)

Dave

[Eric Raeburn]

Hello, Nelson,

I was about to reply to your earlier question on the other thread when I saw this one.

I think between Eric Roseme and Dave Olker you've got a lot of good information on which to base your decision.

You may want to try some performance tests. I did some quite a while ago, and though there are many variables beyond the control of any test, we did see a trend where writes were faster with one protocol and reads were faster with the other (can't remember which, sorry). You can try this yourself with simple 'cp' operations in each direction, just remember to remount between tests (so results come over the wire and not from cache), and to try files of different sizes (that makes a difference).

If you start placing Windows systems into the mix, you'd have to consider what version of NFS is available there, and how actively that code is updated and maintained.

I'm not as uncomfortable as Dave is with the CIFS Client's dependency on NFS, since I work with it every day, and it works. However, NFS is all in the kernel, while the HP CIFS Client and Server are in user space. CIFS, as you know from your "cifslogin" post (did you see my long reply, btw?), has a stricter security model. That may or may not be of value in your environment.

Lots to consider. Both solutions work.

-Eric