Date: Thu, 10 Jul 2008 19:25:40 +0530 From: "Tapan Chaudhari" <tapan.list@gmail.com> To: freebsd-geom@freebsd.org Subject: Re: Can GEOM be used to intercept the I/o calls to an existing mounted device? Message-ID: <482257ad0807100655u1a5c660awfad05564e40e9a95@mail.gmail.com> In-Reply-To: <200807102309.03191.mark@legios.org> References: <482257ad0807100541s2d2c3d1eo6cd57c3a1bc338d1@mail.gmail.com> <200807102309.03191.mark@legios.org>
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Thanks Mark, but unmounting will anyways work. But the problem here will be, a new device "/dev/mirror/gm0" and "/dev/mirror/gm0s1" will be created after :- #gmirror label -v -n -b round-robin gm0 /dev/md0 #gmirror load #gmirror configure -a gm0 and "/dev/md0s1" gets deleted. Now I will have to mount the new device "/dev/mirror/gm0s1" to get my original contents. Can't I do it on the fly while the device is already mounted? I just want that all the calls going to the device "/dev/md0s1" first come to me and then it goes to the original device. In short intercepting the i/o calls. Is there some way I can achieve this? Thanks, On Thu, Jul 10, 2008 at 6:39 PM, Mark Gladman <mark@legios.org> wrote: > On Thursday 10 July 2008 22:41:25 Tapan Chaudhari wrote: > > Hi All, > > I am a newbie to FreeBSD and GEOM. I wanted to intercept the i/o > calls > > going to a particular mounted device by writing some driver. > > I came across geom and thought it might work. I tried to create a new > > device, mount it and then tried using gmirror to mirror the device :- > > > > #dd if=/dev/zero of=file1 bs=1M count=10 > > #dd if=/dev/zero of=file2 bs=1M count=10 > > #mdconfig -f file1 > > #mdconfig -f file2 > > #fdisk -B /dev/mirror/md0 > > #newfs /dev/mirror/md0s1 > > #mkdir /mnt/mirror0 > > #mount /dev/mirror/md0s1 /mnt/mirror0/ > > > > #gmirror label -v -n -b round-robin gm0 /dev/md0 > > gmirror: Can't store metadata on /dev/md0: Operation not permitted. > > > > It gave me this error "gmirror: Can't store metadata on /dev/md0: > Operation > > not permitted." > > > > Am I doing something wrong? Or GEOM does not permit me intercept the i/o > > calls? If not geom, is there any other mechanism by which I can achieve > it? > > > > > > Thanks, > > --Tapan. > > _______________________________________________ > > freebsd-geom@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-geom > > To unsubscribe, send any mail to "freebsd-geom-unsubscribe@freebsd.org" > > Hey, > > You're attempting to set up gmirror on a mounted device. > Unmount /dev/mirror/md0s1 then retry the gmirror command and it should > work. > > Cheers! > Mark >
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