Date: 05 Sep 2002 10:26:57 -0400 From: Lowell Gilbert <freebsd-questions-local@be-well.no-ip.com> To: freebsd-questions@freebsd.org Subject: Re: mount(8) mount_union(8) and the slippery wet floor... Message-ID: <44bs7c1phq.fsf@be-well.ilk.org> In-Reply-To: <20020905091754.GE10717@freepuppy.bellavista.cz> References: <5.1.0.14.0.20020904132723.00bc28e8@mail.lusidor.nu> <20020904124832.GA15994@submonkey.net> <44y9ahecn2.fsf@be-well.ilk.org> <20020905091754.GE10717@freepuppy.bellavista.cz>
next in thread | previous in thread | raw e-mail | index | archive | help
Roman Neuhauser <neuhauser@bellavista.cz> writes: > # freebsd-questions-local@be-well.no-ip.com / 2002-09-04 16:13:53 -0400: > > Ceri Davies <setantae@submonkey.net> writes: > > > > > On Wed, Sep 04, 2002 at 01:46:42PM +0200, Jimmy Lantz wrote: > > > > Hi, > > > > > > > > My question is: > > > > Is the mount union mentioned in MOUNT(8) also affected by the > > > > slippery wet floor in MOUNT_UNION(8)?? > > > > Or can I safely use the mount with the option union? > > > > > > They are the same thing. > > > > For the record, they are *not* the same thing. > > could you elaborate? I'm not 100% sure that I completely understand the technical details, but I'll give it a shot. You could go check the archives of the freebsd-fs list for more authoritative information on the subject. Very briefly, they implement similar functionality through different abstractions. mount_union is a filesystem in its own right -- it "stacks" on top of other filesystem types and uses their capabilities to perform the I/O operations, but to the system I/O code, it looks like a filesystem. The union mount option is visible at a higher level; the filesystem code itself doesn't know about the shadowing. Or something like that. At any rate, they don't seem to share any code. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?44bs7c1phq.fsf>