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Re: ataraid(4) and VOP_OPENing the same block device

On Sep,Saturday 13 2008, at 2:26 AM, Thor Lancelot Simon wrote:

On Fri, Sep 12, 2008 at 02:51:27PM -0700, Bill Stouder-Studenmund wrote:
On Fri, Sep 12, 2008 at 05:09:52AM +0200, Quentin Garnier wrote:

IIUC, the controller allows you to slice disks: e.g., take two halves out of each, build a RAID1 with one set, and a RAID0 with the other. In
this case both disks belong to each array.

Then the right thing to do is somehow export those slices. It makes sense
that different slices can be in different RAIDS, but any given slice
should be in only one.

Yes.  What concerns me is that I'd thought Elad had added code to the
security policy which would in fact make it impossible to use one slice
twice like this -- I'm not sure why what Juan is doing now works.

In device-mapper I use almost the same approach like Juan in ataraid code.
I open physical device once and then I'm using this device for multiple
virtual devices (Logical volumes in lvm) and it works. I'm not sure if is
possible to make device-mapper to work in other way.



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