[Linux-cluster] Samba Technical thread

[John Newbigin]

Christopher R. Hertel wrote:

> On Tue, Dec 07, 2004 at 03:29:32PM +0800, David Teigland wrote:
> :
> 
>>3. POSIX semantics
>>   GFS semantics aim to copy those of a local fs exactly, while others
>>   like NFS don't, although there's nothing precluding that (NFS4 can
>>   be close if not exact).
> 
> 
> Question on this.  Is there any interest in clustered block media?
> 
> Eg., what if five systems all had access to the same chunk of (virtual)  
> disk via iSCSI.  Is there a way that one of those five could create an
> EXT3 filesystem on that raw block-space such that all of the five 
> clustered systems would see an EXT3 partition (and be able to use it 
> concurrently)?
No (well not for a writable filesystem).  You still need a cluster 
filesystem so you don't trash the filesystem.  I believe that work is 
underway for a cluster raid to run gfs on top of.  This would be good 
for people without shared storage hardware but still want to use GFS.
> 
> Oh... and a side-comment.  CIFS tries, and gets fairly close, to copy 
> lovsl FS semantics.  The problem is that those semantics are DOS, OS/2, 
> and NTFS semantics.  The protocol has support for all of these, and there 
> are some folks who have tried to add Unix semantics as well.
I did the initial implementation of the Unix semantics in the smbfs 
driver.  POSIX semantics just aren't possible over CIFS.  Unlinking an 
open file for example.  I tried for weeks to implement that in smbfs and 
samba.  Windows does not have such a concept so it is very difficult to 
make it work over CIFS.  This means that programs that do stupid NFS 
locking workarounds (like gconfd) won't run with CIFS mounted home 
directories.

John.

> 
> Chris -)-----
> 


-- 
John Newbigin
Computer Systems Officer
Faculty of Information and Communication Technologies
Swinburne University of Technology
Melbourne, Australia
http://www.it.swin.edu.au/staff/jnewbigin