Date: Tue, 15 Jul 2008 00:35:06 +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: <482257ad0807141205i1d5e2c2co4b609a9f5b7015b@mail.gmail.com> In-Reply-To: <482257ad0807111209g20cdb0f6j9f7000fd57a7287a@mail.gmail.com> References: <482257ad0807100541s2d2c3d1eo6cd57c3a1bc338d1@mail.gmail.com> <200807102309.03191.mark@legios.org> <482257ad0807100655u1a5c660awfad05564e40e9a95@mail.gmail.com> <482257ad0807111129i66ac4372sbc9b4d4ef7675e9d@mail.gmail.com> <482257ad0807111209g20cdb0f6j9f7000fd57a7287a@mail.gmail.com>
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Hi All,
I am not able to find ways to intercept the i/o calls. I will need your
help to move ahead.
One thing to mention is 'mirror' is just an example. I want to write a new
driver which will intercept the i/o calls. This is the first major milestone
to achieve. Needed your help. Any pointers and directions will do.
Thanks,
--Tapan.
On Sat, Jul 12, 2008 at 12:39 AM, Tapan Chaudhari <tapan.list@gmail.com>
wrote:
> Hi,
> I got the problem resolved of not getting mails. It was the stupid of me
> that changed the settings :-).. I have unchecked the digest.
>
> Did Ivan sent some attachment with the mail? An attachment was scrubbed in
> the digest I received. Sorry for the trouble but still, can anyone resend
> it?
> Expecting some help regarding "interception mechanism" from all of you.
>
>
> Thanks,
> --Tapan.
>
>
> On Fri, Jul 11, 2008 at 11:59 PM, Tapan Chaudhari <tapan.list@gmail.com>
> wrote:
>
>> Hey guys,
>> First of all, I was not able to receive your replies to my mail. I
>> don't know the reason but I am already subscribed to the list. I got to know
>> about your replies from the digest i received today. I have written a mail
>> to the mailing list owner describing this problem. Hope this does not happen
>> again.
>>
>>
>> Well regarding GEOM as Poul mentioned he has already done this
>> interception mechanism in GEOM, Poul can you please help me out by giving
>> some directions as to how to move ahead and implement the interceptions of
>> i/o to a particular device? I would be really happy to get any help
>> regarding the interception mechanism.
>>
>> Thanks,
>> --Tapan.
>>
>>
>> On Thu, Jul 10, 2008 at 7:25 PM, Tapan Chaudhari <tapan.list@gmail.com>
>> wrote:
>>
>>> 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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