Oplocks - when do they help
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From: Volker Lendecke on 22 May 2010 13:00 On Sat, May 22, 2010 at 06:21:52PM +0300, Uri Simchoni wrote: > I googled around and the general wisdom seems to be that > oplocks provide a performance gain if files are accessed > by a single client at a time (that is, if the oplock does > not break). > > What I can't figure out is what test can show this > performance gain. I mean, theoretically, document-editing > applications (Word,excel) save and load whole files and > hence do not benefit from oplocks. Applications which do > modify portions of a file usually flush buffers to > maintain transactional integrity and hence should not > benefit from oplocks either. > > So, how can I demonstrate the benefit of oplocks? Use an Access .mdb file. Volker -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
From: Uri Simchoni on 22 May 2010 13:20 So a single-user mdb benefits from oplocks, multi-user mdb suffers from oplocks, and applications that load/store whole files are indifferent to it? Thanks, Uri. > Date: Sat, 22 May 2010 18:55:02 +0200 > From: Volker.Lendecke(a)SerNet.DE > To: uri_simchoni(a)hotmail.com > CC: samba(a)lists.samba.org > Subject: Re: [Samba] Oplocks - when do they help > > On Sat, May 22, 2010 at 06:21:52PM +0300, Uri Simchoni wrote: > > I googled around and the general wisdom seems to be that > > oplocks provide a performance gain if files are accessed > > by a single client at a time (that is, if the oplock does > > not break). > > > > What I can't figure out is what test can show this > > performance gain. I mean, theoretically, document-editing > > applications (Word,excel) save and load whole files and > > hence do not benefit from oplocks. Applications which do > > modify portions of a file usually flush buffers to > > maintain transactional integrity and hence should not > > benefit from oplocks either. > > > > So, how can I demonstrate the benefit of oplocks? > > Use an Access .mdb file. > > Volker _________________________________________________________________ Hotmail: Free, trusted and rich email service. https://signup.live.com/signup.aspx?id=60969 -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
From: Volker Lendecke on 22 May 2010 13:30 On Sat, May 22, 2010 at 08:10:09PM +0300, Uri Simchoni wrote: > So a single-user mdb benefits from oplocks, multi-user mdb > suffers from oplocks, and applications that load/store > whole files are indifferent to it? Not necessarily. I do know that MS Access suffers a lot without oplocks, I have seen a factor of 10 between an oplocked file and one without oplocks. This happened both against Windows and also against Samba. Everything else very much depends on the application. Without oplocks the Windows redirector (the compontent that makes d: come from the net) passes the Win32 API calls directly to the wire. So if the application decides to read a gigabyte large file byte by byte, then it will severely suffer from missing oplocks. With oplocks the Windows redirector will coalesce and pre-read much larger blocks. If your application at hand however at the win32 level already reads in large chunks, you will see not much difference. Can you take a look at your applications and see what they do? Volker -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
From: Uri Simchoni on 22 May 2010 13:40 > Date: Sat, 22 May 2010 19:21:32 +0200 > From: Volker.Lendecke(a)SerNet.DE > To: uri_simchoni(a)hotmail.com > CC: samba(a)lists.samba.org > Subject: Re: [Samba] Oplocks - when do they help > > On Sat, May 22, 2010 at 08:10:09PM +0300, Uri Simchoni wrote: > > So a single-user mdb benefits from oplocks, multi-user mdb > > suffers from oplocks, and applications that load/store > > whole files are indifferent to it? > > Not necessarily. I do know that MS Access suffers a lot > without oplocks, I have seen a factor of 10 between an > oplocked file and one without oplocks. This happened both > against Windows and also against Samba. > > Everything else very much depends on the application. > Without oplocks the Windows redirector (the compontent that > makes d: come from the net) passes the Win32 API calls > directly to the wire. So if the application decides to read > a gigabyte large file byte by byte, then it will severely > suffer from missing oplocks. With oplocks the Windows > redirector will coalesce and pre-read much larger blocks. If > your application at hand however at the win32 level already > reads in large chunks, you will see not much difference. > > Can you take a look at your applications and see what they > do? > > Volker What I'm really after is whether I should worry about oplocks in a Samba server or just turn them off. The reason for worrying is that I have the same file accessed using 2 shares: one "normal" and one that sits upon a special file system (linux fuse-based) that's really a layer above the normal file system. I cannot say what types of applications access these shares - they are for general use. What I understand is that I should make oplocks work if possible (I understand that for starters, that dev/inode pair through both access points should be the same). Thanks for the quick reply! Uri. _________________________________________________________________ Hotmail: Powerful Free email with security by Microsoft. https://signup.live.com/signup.aspx?id=60969 -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba
From: Fred Kienker on 23 May 2010 07:30
> -----Original Message----- > > Use an Access .mdb file. > > Volker > -- > To unsubscribe from this list go to the following URL and read the > instructions: https://lists.samba.org/mailman/options/samba > Volker: I've been setting up Samba servers for years under the impression (delusion) that Samba can't handle multiple users on Access .mdb files correctly with op locks turned on. Has this changed in the 3.5.x branch? Best regards, Fred Fred Kienker AT4B "Advanced Technologies for Business" This transmission may contain information that is privileged, confidential and/or exempt from disclosure under applicable law. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or use of the information contained herein (including any reliance thereon) is STRICTLY PROHIBITED. If you received this transmission in error, please immediately contact the sender and destroy the material in its entirety, whether in electronic or hard copy format. Thank you. -- To unsubscribe from this list go to the following URL and read the instructions: https://lists.samba.org/mailman/options/samba |