Re: [Samba] Difference in Samba and CIFS interms of keeping the deleted files opened
On Tue, Jul 21, 2009 at 12:12 AM, Jeremy Allison j...@samba.org wrote: On Mon, Jul 20, 2009 at 10:14:49PM +0530, Nikhil wrote: Hi, We have a CIFS server running on a NetApp server and a Solaris host running Samba-3.3.2. When we mount both the filesystems to a Drive on a Windows using the net use command and then try to run a java program which basically does nothing but continuosly writes a data chunk to a file. On a side note, these same filesystems are accessible on a Solaris (unix) host too. When the java program is run and a file is being generated, I go to my unix terminal and happen to delete the file generated by the java program. Interestingly, there is an IOexception caught in the java program running on the Windows machine, when the file is deleted on the CIFS based filesystem (available on Solaris as a NFS filesystems) but there is no exception caught when the filesystem happens to be Samba (available on Solaris as /var , a regular partition). I delete the file from Unix as the process demands, but also there is no way to delete a in-use-file in Windows. I would like to understand the differences in Samba and CIFS in this context especially why is that so there is an IOexception for a CIFS based filesystem but not on the samba filesystem. This is reproducible at will. What could be wrong? What could be made to make samba filesystem also behave the same way to throw exceptions (Exceptions are good than that not at all knowing there is a file that is deleted but being still written onto.) Ok, I think the reason that you're having this problem is that you're running Samba on Solaris in this case, sad to say. I don't believe Sun have exposed kernel level oplock (lease) capability to user space processes, so Samba on Solaris has no way of knowing that a unix user deleted the file. Samba running on Linux, (or SGI Irix) has kernel level oplocks, so can detect access from the local filesystem. As the NetApp runs a custom kernel (derived a long time ago from FreeBSD I believe) then their CIFS implementation (like Samba on Linux) knows when a NFS user has modified the file. Jeremy. Thanks Jeremy. Appreciate your response. That actually sounds interesting... do we have this documented or referenced as a bug somewhere that I can lookup? What I see from the CIFS protocol: - When client B opens the file, the server must synchronize with client A in case client A has any buffered locks. Once it is synchronized, client B's open request may be completed. Client B, however, is informed that he has a level II oplock, rather than an exclusive oplock to the file. In this case, no client that has the file open with a level II oplock may buffer any lock information on the local client machine. This allows the server to guarantee that if any write operation is performed, it need only notify the level II clients that the lock should be broken without having to synchronize all of the accessors of the file. The level II oplock may be broken to none, meaning that some client that had the file opened has now performed a write operation to the file. I do not understand whether Solaris fails to respect the level II oplock or how does Samba can be made aware of the kernel level oplocks (is there a no way?). BTW, to check it myself on what you said I ran samba-3.0.25 on a Linux machine with kernel version 2.4.21-47.0.1.ELsmp and ran smbd and then did the same tests. - Ran java program on Windows which writes to the file continuously on a samba exported filesystem from a Linux box - on the Linux terminal, I go and delete the file - Windows does NOT recognise that there is a opened file deleted and the Java program does NOT thrown any exception... sadly. So, I do not have a Linux box with kernel -2.6, so if that means to say that Linux kernel has introduced kernel level oplocks facility in the 2.6 kernel then I would have to try that... Thanks. -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
Re: [Samba] Difference in Samba and CIFS interms of keeping the deleted files opened
On Tue, Jul 21, 2009 at 12:10 PM, Nikhil mnik...@gmail.com wrote: On Tue, Jul 21, 2009 at 12:12 AM, Jeremy Allison j...@samba.org wrote: On Mon, Jul 20, 2009 at 10:14:49PM +0530, Nikhil wrote: Hi, We have a CIFS server running on a NetApp server and a Solaris host running Samba-3.3.2. When we mount both the filesystems to a Drive on a Windows using the net use command and then try to run a java program which basically does nothing but continuosly writes a data chunk to a file. On a side note, these same filesystems are accessible on a Solaris (unix) host too. When the java program is run and a file is being generated, I go to my unix terminal and happen to delete the file generated by the java program. Interestingly, there is an IOexception caught in the java program running on the Windows machine, when the file is deleted on the CIFS based filesystem (available on Solaris as a NFS filesystems) but there is no exception caught when the filesystem happens to be Samba (available on Solaris as /var , a regular partition). I delete the file from Unix as the process demands, but also there is no way to delete a in-use-file in Windows. I would like to understand the differences in Samba and CIFS in this context especially why is that so there is an IOexception for a CIFS based filesystem but not on the samba filesystem. This is reproducible at will. What could be wrong? What could be made to make samba filesystem also behave the same way to throw exceptions (Exceptions are good than that not at all knowing there is a file that is deleted but being still written onto.) Ok, I think the reason that you're having this problem is that you're running Samba on Solaris in this case, sad to say. I don't believe Sun have exposed kernel level oplock (lease) capability to user space processes, so Samba on Solaris has no way of knowing that a unix user deleted the file. Samba running on Linux, (or SGI Irix) has kernel level oplocks, so can detect access from the local filesystem. As the NetApp runs a custom kernel (derived a long time ago from FreeBSD I believe) then their CIFS implementation (like Samba on Linux) knows when a NFS user has modified the file. Jeremy. Thanks Jeremy. Appreciate your response. That actually sounds interesting... do we have this documented or referenced as a bug somewhere that I can lookup? What I see from the CIFS protocol: - When client B opens the file, the server must synchronize with client A in case client A has any buffered locks. Once it is synchronized, client B's open request may be completed. Client B, however, is informed that he has a level II oplock, rather than an exclusive oplock to the file. In this case, no client that has the file open with a level II oplock may buffer any lock information on the local client machine. This allows the server to guarantee that if any write operation is performed, it need only notify the level II clients that the lock should be broken without having to synchronize all of the accessors of the file. The level II oplock may be broken to none, meaning that some client that had the file opened has now performed a write operation to the file. I do not understand whether Solaris fails to respect the level II oplock or how does Samba can be made aware of the kernel level oplocks (is there a no way?). BTW, to check it myself on what you said I ran samba-3.0.25 on a Linux machine with kernel version 2.4.21-47.0.1.ELsmp and ran smbd and then did the same tests. - Ran java program on Windows which writes to the file continuously on a samba exported filesystem from a Linux box - on the Linux terminal, I go and delete the file - Windows does NOT recognise that there is a opened file deleted and the Java program does NOT thrown any exception... sadly. So, I do not have a Linux box with kernel -2.6, so if that means to say that Linux kernel has introduced kernel level oplocks facility in the 2.6 kernel then I would have to try that... Thanks. Jeremy, I looked at the enabling kernel oplocks in the samba configuration file and I have enabled kernel oplocks = yes in the [global] section on both of Linux-2.6.18-92 and Linux-2.4.21-47.0.1.ELsmp kernel machines running the samba and I notice that the behaviour is not as what is said. I still do not see the exception being NOT caught on Windows java program when I delete the file from a Unix terminal. Any idea, where I could be going wrong? -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
Re: [Samba] Difference in Samba and CIFS interms of keeping the deleted files opened
Nikhil, I looked at the enabling kernel oplocks in the samba configuration file and I have enabled kernel oplocks = yes in the [global] section on both of Linux-2.6.18-92 and Linux-2.4.21-47.0.1.ELsmp kernel machines running the samba and I notice that the behaviour is not as what is said. I still do not see the exception being NOT caught on Windows java program when I delete the file from a Unix terminal. Any idea, where I could be going wrong? It sounds more like smbd maintains the opens file descriptor as long as the client has an open file handle. Standard POSIX semantics allow you to delete open files with the inode finally being released after the last open fd is closed. I could speculate that it may be less to do with CIFS and more to do with the server OS. But that is pure speculation. Have you looked at a network trace to see which SMB op caused the IO Exception? Does truncating rather than removing the file change the application behavior? cheers, jerry -- = http://www.plainjoe.org/ What man is a man who does not make the world better? --Balian signature.asc Description: OpenPGP digital signature -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
Re: [Samba] Difference in Samba and CIFS interms of keeping the deleted files opened
On Tue, Jul 21, 2009 at 5:06 PM, Gerald Carter je...@plainjoe.org wrote: Nikhil, I looked at the enabling kernel oplocks in the samba configuration file and I have enabled kernel oplocks = yes in the [global] section on both of Linux-2.6.18-92 and Linux-2.4.21-47.0.1.ELsmp kernel machines running the samba and I notice that the behaviour is not as what is said. I still do not see the exception being NOT caught on Windows java program when I delete the file from a Unix terminal. Any idea, where I could be going wrong? It sounds more like smbd maintains the opens file descriptor as long as the client has an open file handle. Standard POSIX semantics allow you to delete open files with the inode finally being released after the last open fd is closed. I could speculate that it may be less to do with CIFS and more to do with the server OS. But that is pure speculation. Have you looked at a network trace to see which SMB op caused the IO Exception? Does truncating rather than removing the file change the application behavior? cheers, jerry -- = http://www.plainjoe.org/ What man is a man who does not make the world better? --Balian Hi Jeremy, Yeah.. I tried oplocking thing (btw, is there any set-direct-go howto on oplocking configuration parameters to be used smb.conf?) and checked via the smbstatus that the file is being into the samba lock. But when I rm the file from the Unix terminal, the windows program does not detect the file deletion. it may be less to do with CIFS and more to do with the server OS. But that is pure speculation. agreed. I am running Solaris-10 where kernel oplock is not available, so will rule that out. I have linux box with 2.6 kernel and kernel oplocks=yes set in smb.conf; but that still does not help in getting the sync set. Does truncating rather than removing the file change the application behavior? Interesting. I do /bin/cp -f /dev/null /var/tmp/test.log and I notice that ls -l does not show that the file is truncated at all even though I do it multiple times; ls -l still does not show that the file is truncated. Am I missing something that why is rm command or deleting the file behaviour would differ? BTW, this is the output of testparam -s -v | grep -i lock output: Load smb config files from /var/samba/smb.conf Processing section [homes] Processing section [printers] Processing section [tmpdir] Loaded services file OK. Server role: ROLE_STANDALONE kernel oplocks = Yes lock spin time = 200 oplock break wait time = 0 lock directory = /var/samba/locks usershare path = /var/samba/locks/usershares block size = 1024 veto oplock files = blocking locks = Yes fake oplocks = No locking = Yes oplocks = Yes level2 oplocks = Yes oplock contention limit = 2 posix locking = Yes strict locking = Yes Can you please let me know if any of the parameters need something else/need not put? Thanks again, Jeremy. -- Nikhil -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
[Samba] Difference in Samba and CIFS interms of keeping the deleted files opened
Hi, We have a CIFS server running on a NetApp server and a Solaris host running Samba-3.3.2. When we mount both the filesystems to a Drive on a Windows using the net use command and then try to run a java program which basically does nothing but continuosly writes a data chunk to a file. On a side note, these same filesystems are accessible on a Solaris (unix) host too. When the java program is run and a file is being generated, I go to my unix terminal and happen to delete the file generated by the java program. Interestingly, there is an IOexception caught in the java program running on the Windows machine, when the file is deleted on the CIFS based filesystem (available on Solaris as a NFS filesystems) but there is no exception caught when the filesystem happens to be Samba (available on Solaris as /var , a regular partition). I delete the file from Unix as the process demands, but also there is no way to delete a in-use-file in Windows. I would like to understand the differences in Samba and CIFS in this context especially why is that so there is an IOexception for a CIFS based filesystem but not on the samba filesystem. This is reproducible at will. What could be wrong? What could be made to make samba filesystem also behave the same way to throw exceptions (Exceptions are good than that not at all knowing there is a file that is deleted but being still written onto.) I would be willing to work and share the procedure to reproduce this behaviour with anyone aware of the Samba/CIFS protocols. -- Nikhil -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
Re: [Samba] Difference in Samba and CIFS interms of keeping the deleted files opened
On Mon, Jul 20, 2009 at 10:14:49PM +0530, Nikhil wrote: Hi, We have a CIFS server running on a NetApp server and a Solaris host running Samba-3.3.2. When we mount both the filesystems to a Drive on a Windows using the net use command and then try to run a java program which basically does nothing but continuosly writes a data chunk to a file. On a side note, these same filesystems are accessible on a Solaris (unix) host too. When the java program is run and a file is being generated, I go to my unix terminal and happen to delete the file generated by the java program. Interestingly, there is an IOexception caught in the java program running on the Windows machine, when the file is deleted on the CIFS based filesystem (available on Solaris as a NFS filesystems) but there is no exception caught when the filesystem happens to be Samba (available on Solaris as /var , a regular partition). I delete the file from Unix as the process demands, but also there is no way to delete a in-use-file in Windows. I would like to understand the differences in Samba and CIFS in this context especially why is that so there is an IOexception for a CIFS based filesystem but not on the samba filesystem. This is reproducible at will. What could be wrong? What could be made to make samba filesystem also behave the same way to throw exceptions (Exceptions are good than that not at all knowing there is a file that is deleted but being still written onto.) Ok, I think the reason that you're having this problem is that you're running Samba on Solaris in this case, sad to say. I don't believe Sun have exposed kernel level oplock (lease) capability to user space processes, so Samba on Solaris has no way of knowing that a unix user deleted the file. Samba running on Linux, (or SGI Irix) has kernel level oplocks, so can detect access from the local filesystem. As the NetApp runs a custom kernel (derived a long time ago from FreeBSD I believe) then their CIFS implementation (like Samba on Linux) knows when a NFS user has modified the file. Jeremy. -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
