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The 2007 Linux Storage and File Systems WorkshopThe 2007 Linux Storage and File Systems WorkshopPosted Mar 20, 2007 9:16 UTC (Tue) by hein.zelle (guest, #33324)Parent article: The 2007 Linux Storage and File Systems Workshop
NFS developments>
Our current solution (nfs for linux/linux and samba for linux/windows) gives all kinds of problems, ranging from no proper authentication for nfs shares, and non-functional access control when trying to mount samba shares from windows machines.
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The 2007 Linux Storage and File Systems Workshop Posted Mar 20, 2007 17:16 UTC (Tue) by bronson (subscriber, #4806) [Link] There's no good solution today. The Samba team, however, is working very hard to make CIFS the best Unix<->Unix and Unix<->Windows network filesystem. We'll see when Samba 4 ships... So far, it's looking very promising.
The 2007 Linux Storage and File Systems Workshop Posted Mar 20, 2007 20:03 UTC (Tue) by k8to (subscriber, #15413) [Link] The piece I haven't seen so far is "here's how to configure samba to remove all the crap you don't care about if you haven't got windows". Granted, the Samba 4 hasn't shipped, but a document or setting along those lines would be useful *now*. Does it exist?
When I went looking I found a whole lot of complexity. I was really *not* interested in learning all the details of SMB and windows networking, I just wanted my Linux machines to share files.
The 2007 Linux Storage and File Systems Workshop Posted Mar 20, 2007 23:25 UTC (Tue) by drag (subscriber, #31333) [Link] I doubt it's usefull for large numbers of users, but for my personal stuff the fuse-based Sshfs is a superior replacement to NFS or Samba.
Faster, strong encryption, strong authentication aviable, trivially easy to setup. Robust.
The downside is that you can't use it for anything that requires special file typs, like named pipes. So ~/ is out. No booting from it. But for serving up large media files or sharing abritrary directories between computers it's great.
The 2007 Linux Storage and File Systems Workshop Posted Mar 21, 2007 12:25 UTC (Wed) by nix (subscriber, #2304) [Link] Of course, you can't usefully store named pipes or devices on NFS-shared filesystems, either...
The 2007 Linux Storage and File Systems Workshop Posted Mar 21, 2007 15:53 UTC (Wed) by k8to (subscriber, #15413) [Link] You've mentioned this before in response to my discussing of issuses encountered trying to use NFS for similar purposes.
My response is still that sshfs is a great thing, and pretty useful for trivial tasks, or remote manipulation of low-bandiwidth, high-latency small set sof files. It's much easier to edit some remote configuration thing with a local tool via sshfs than most anything else.
But sshfs still can't handle a variety of normal file sharing activities reasonably. It fails entirely on mmap and large files make it choke because it hasn't got sufficient cache sophistication. Over a LAN you'll never get 10% of your throughput while maxing your CPUs on the ciphers. If the ssh link actually goes down (this happens), the whole thing gets very unhappy and it is impossible to recover.
Basically the only thing that makes sshfs "better" than the traditional lousy network filesystems we love to hate is that it has a well defined focus. It's a no-server-configuration filesystem for accessing small numbers of smallish files without high performance expectations. It is a remarkably pleasant tool when used inside its scope, but one of the reasons it is pleasant is it has a much narrower scope.
The 2007 Linux Storage and File Systems Workshop Posted Mar 21, 2007 0:02 UTC (Wed) by saffroy (subscriber, #43999) [Link] "There's no good solution today."
Of course there is one, it's called OpenAFS. Except installing and managing an AFS cell is not quite easy (although the Debian packager provides useful scripts to quickly start a simple server)...
But AFS has its share of good features:
...and more. :)
I've used OpenAFS on Linux for years, and never complained (it helps that I have a competent and knowledgeable admin).
The 2007 Linux Storage and File Systems Workshop Posted Mar 21, 2007 2:54 UTC (Wed) by drag (subscriber, #31333) [Link] OpenAFS is, indeed, very nice.
But it's Windows support is crap. Not because OpenAFS is not cool, but because Window uses SMB or Microsoft's DFS to do it's thing and nobody else's. OpenAFS has to use a sort of SMB emulation were it deals with AFS stuff then translates that to something that the system can use.
But if your just dealing with Linux clients then that's not a problem.
Also the file and directory permission model is bizzare and isn't realy compatable with just standard Unix-style ACL (user/group/world read/write/execute) model. So people used to Linux permissions have to relearn how to deal with AFS permissions.
It's not posix, and it's not compatable with special file types like named pipes.
Also there is no real way to access your data unless your AFS server stuff is actually running. OpenAFS tends to incure a higher amount of knowledge and administration stuff isn't very easy to deal with.
Then it's large file performance is realy bad. It's just plain slow and the volumes are very limited in size.
What it's VERY good for is if you have a large distributed network.
Say you have a wireless network or a WAN-wide thing were you have a entire campus of computers to take care off. It handles disconnection very well, it's caching support is very good for semi-offline work (ie you can still edit a file even if you temporarially lost contact with the servers.
It's security stuff is nice. The volume management is very nice, snapshotting and mirroring stuff. It's safe to use over the internet and unencrypted wireless networks.
And as a special bonus it's /afs/ directory tree is very handy. It allows people to move volumes around, change servers, setup mirrors, and all sorts of stuff without having to have the clients know of any of these changes. Were as with NFS or SAMBA if you change out file servers or whatnot then the clients all have to be reconfigured to know the new locations and names of the servers and directories. With OpenAFS this is not nessicary.
But considuring the lack of posix support and poor large file performance as well as permission issues it's not realy a replacement for NFS. It's a alternative that is usefull in places were NFS is not.
And it's poor Windows support means that it's not usefull as a replacement for Samba.
But it's nice.
The OpenAFS points out a huge problem for Linux in general though. AFS is ancient. It's old old old. It's like X Windows/Athena/Kerberos ancient. Still, even with it's age, it's still MUCH more sophisticated then NFS or SMB network protocols. Nobody has realy produced anything better.
Lustre, maybe. It certainly has a lot of cool features and is fast. But I don't think that it has any security.
Supports lots of stuff. TCP networking, ininaband, and all sorts of other bizzare interconnects.
Supports ACLs, extended ACLs, extended attributes. Lots of high aviability and high performance features. Failover, extra redudancy. You can use it as root FS. It supports Quotas.
It doesn't require special patches and kernel recompiles for Linux client support.
The only thing that it lacks is robust security. They plan on supporting GSSAPI and Kerberos with the 1.8.0 release. This is due out by the end of this year according to their roadmap...
The 2007 Linux Storage and File Systems Workshop Posted Mar 21, 2007 13:47 UTC (Wed) by saffroy (subscriber, #43999) [Link] It's nice that you mention Lustre, actually I was kind of surprised that it would not be mentioned in this article. Lustre definitely has a great potential (great scalability, sequential I/O performance, client cache, excellent POSIX conformance), and I feel it could be a good general purpose global fs someday.
That is, if its creators (CFS) let it grow out of its niche HPC market: at the moment, I feel they're more concerned about implementing the features asked by their paying customers, which are big supercomputing centers. I'm certainly not blamining them for that, but for instance, they are more sensitive to large file throughput (tens of GB/s) than to file creation rates (Lustre is still damn slow here).
If the community or the customers push in the right direction, Lustre can become an excellent distributed fs for nearly everyone, but I feel it has yet to happen -- and I hope it will.
Oh, and don't take CFS roadmaps too seriously. ;-)
The 2007 Linux Storage and File Systems Workshop Posted Mar 22, 2007 2:01 UTC (Thu) by drag (subscriber, #31333) [Link] I don't take them too seriously. :)
But they aren't to far off. One thing worth noting is that Ext4 integration isn't mentioned anywere on them, but it's obvious that Ext4 is going to play a large part in it.
One thing about CFS, which I think is important to keep in mind, is that they are decendents of the failed Coda and then the Intermezzo projects. I don't know the exact relationships, but I think that they were developers in those projects.
The thing is is that they learned the hard way that distributed network file system protocols aren't a easy thing to make, even if you are good at it. It takes a lot of time and effort to get anything going and a long time of development to get to the point were you can actually release anything.
So it's not something that lends itself to the Linux-style development proccess of 'release early', 'release often'.
So they formed CFS to pursue the money nessicary to support themselves while they hacked on Lustre full time. The HPC market is the easiest and most profitable place to target for this sort of stuff, and they know that from Beowolf stuff that open source and distributed computing can lead to dramatic results.
The 2007 Linux Storage and File Systems Workshop Posted Mar 22, 2007 11:56 UTC (Thu) by nix (subscriber, #2304) [Link] Of course Coda itself was an enhancement of AFS (losing most of its scalability in the process, though)...
The 2007 Linux Storage and File Systems Workshop Posted Mar 22, 2007 17:08 UTC (Thu) by jwb (subscriber, #15467) [Link] What do you mean by Ext4 integration? Lustre already includes all Ext4 features and then some. In fact you might say that Ext4 is just rolling features into the mainline kernel that have long been used in Lustre. mballoc, delalloc, and extents have all been in Lustre for years.
The 2007 Linux Storage and File Systems Workshop Posted Mar 22, 2007 10:20 UTC (Thu) by wingo (subscriber, #26929) [Link] This would be a nice topic to revisit in an article -- networked filesystems. Samba for unix<->unix is something I'd like to know more about.
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