[Samba] Re: Samba 2.2.3 Oplock problem...

Rashkae rashkae at wealthmap.ca
Wed Feb 6 08:39:27 GMT 2002

Home drives or files that are opened by only one user at a time would see
the greatest benefit of oplocks.  In this case, oplock can dramatically
improve both read and write performance with caching on the client.

On Wed, 6 Feb 2002, Noel Kelly wrote:

So, Martyn would it be true to say this:

Oplocks should only really be used in situations where a server is sharing
program files or other relatively static data ?

Home drives and other files which are primarily only opened by one user at a
time would see no value in oplocks ?

Databases and other dynamic data shares which can be altered by many users
should certainly have oplocks disabled ?

Thanks for your insight.

-----Original Message-----
From: Martyn Ranyard [mailto:ranyardm at lineone.net]
Sent: 06 February 2002 13:02
To: Russell Senior; jra at samba.org
Cc: Samba Maillist (E-mail)
Subject: Re: [Samba] Re: Samba 2.2.3 Oplock problem...

I remember a talk at our lug about oplocks,  If I remember correctly then
the following is true :

A client takes the file, caches it at client side, and oplocks it.
The server then gets a different request to read the file, asks the client
to send it's latest version.
Here, two things can happen, 1. the client responds with changes, which the
server reflects or 2. the client doesn't respond in time, in which case the
server breaks the oplock and reverts the file to it's unchanged
state.  This is the way SMB oplocks work AFAIK

Network problems can cause delays and therefore timeouts will timeout (it
is their job, afterall).  This is why leaky networks cause oplock problems.

I contribute this hazy knowledge to the public domain, mainly to save
Jeremy some time!

At 08:59 AM 2/5/02 -0800, Russell Senior wrote:
> >>>>> "Jeremy" == Jeremy Allison <jra at samba.org> writes:
>Jeremy> Most oplock problems are due to bad network setups (client
>Jeremy> drivers, hubs etc). I haven't seen any evidence other than one
>Jeremy> person having oplock problems (which is not unusual given the
>Jeremy> state of many networks) that this is anything other than the
>Jeremy> usual network related oplock woes.
>Can you elaborate on this?  As I understand it, the oplock break
>messages are getting lost, but aren't they sent over the TCP socket?
>Won't the regular TCP reliability guarantees ensure it gets resent if
>not ACK'd?  How can network problems interfere?
>Russell Senior         ``The two chiefs turned to each other.
>seniorr at aracnet.com      Bellison uncorked a flood of horrible
>                          profanity, which, translated meant, `This is
>                          extremely unusual.' ''
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Martyn Ranyard

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