From owner-freebsd-fs Sun Apr 2 6:53:54 2000 Delivered-To: freebsd-fs@freebsd.org Received: from ewok.creative.net.au (ewok.creative.net.au [203.30.44.41]) by hub.freebsd.org (Postfix) with SMTP id 7832537B99A for ; Sun, 2 Apr 2000 06:53:48 -0700 (PDT) (envelope-from freebsd@ewok.creative.net.au) Received: (qmail 52804 invoked by uid 1008); 2 Apr 2000 13:53:24 -0000 Date: Sun, 2 Apr 2000 21:53:24 +0800 From: Adrian Chadd To: vova@express.ru Cc: Bernd Walter , freebsd-fs@FreeBSD.ORG Subject: Re: SCSI bus Message-ID: <20000402215318.E21291@ewok.creative.net.au> References: <20000402110216.A24876@cicely8.cicely.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.95.4i In-Reply-To: ; from vova@express.ru on Sun, Apr 02, 2000 at 03:38:10PM +0400 Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Sun, Apr 02, 2000, vova@express.ru wrote: > On Sun, 2 Apr 2000, Bernd Walter wrote: > > > > > I don't expect this to work because the readonly side can't know when the > > > > incore informations outdates. > > > > > > Yes, it can be a problem, but may be this may be solved by disabling any > > > cache on read-only side (or setting expire time in one sec) ? > > > > You can't diable readcaching completely. > > Say you need the inode, then you will read it and finaly use it. > > You don't reread it for every single byte you access which creates some kind of > > read cache. And there are much more complex points like this sample. > > Ok, have kernel algorithm to "expire" cached vnodes ? Or vnodes only > pushed out by new pages ? > > In my case writes - relative rare case then reads and I can wait for some > timeout while my in-kernel vnodes will dropped to see new from disk Think from a metadata point of view - if you're half way through updating a directory on a write, and you try reading that directory, you are going to get very weird results. You'd need to have a filesystem that supports this kind of access at the very outside. FFS wasn't designed for this. Adrian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message