Date: Sat, 20 Sep 2003 23:10:06 -0500 (CDT) From: Chris Dillon <cdillon@wolves.k12.mo.us> To: Mark Bojara <mark@aboutit.co.za> Cc: freebsd-questions@freebsd.org Subject: Re: write behind caching Message-ID: <20030920224159.Y66088@duey.wolves.k12.mo.us> In-Reply-To: <20030918160749.C353-100000@opium.co.za> References: <20030918160749.C353-100000@opium.co.za>
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Moved to freebsd-questions, which is more appropriate... On Thu, 18 Sep 2003, Mark Bojara wrote: > One of our clients is running a FreeBSD 4.8 server with Samba for > his Windows based financial system. He is having problems that the > index files get corrupt. He phoned support for the financial system > they told him he must disable "Write behind caching" on the server, > However this is for a M$ server. Is there something equivilent for > FreeBSD? This is almost always due to an application programming error, but you can't tell the developers that, and instead of fixing their problem, the developers nearly always tell you to turn off "write caching". What they really mean to say is "opportunistic locking". Turn that off in Samba and things will work smoothly, though much slower. This has _ABSOLUTELY NOTHING_ to do with any write caching performed by the server OS or storage subsystem, nor with their "sync" behaviours. This is entirely client-side caching (though server-orchestrated) and has only to do with SMB file locking and a _client_ performing write caching on a network file while other clients are performing read caching on the same file, and the whole ballet of cache flushings don't happen when they're supposed to. Or something like that. Before you turn off opportunistic locking, though, if the application uses the Microsoft Data Access Components (MDAC) and/or Jet for its database backend, download the latest MDAC and/or Jet release from Microsoft's web site and install it on _every_ workstation. That kind of thing is ideal to put in a login script while using the silent install option. I believe the latest MDAC release is 2.8, and the latest Jet is 4.0 SP7. It will never hurt to install both, even if it turns out your application uses neither. -- Chris Dillon - cdillon(at)wolves.k12.mo.us FreeBSD: The fastest and most stable server OS on the planet - Available for IA32, IA64, PC98, Alpha, and UltraSPARC architectures - x86-64, PowerPC, ARM, MIPS, and S/390 under development - http://www.freebsd.org Q: Because it reverses the logical flow of conversation. A: Why is putting a reply at the top of the message frowned upon?
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