On Fri, 29 Apr 2011 05:39:40 +0100, Ben Hutchings <ben@xxxxxxxxxxxxxxx> wrote: > On Wed, 2011-04-27 at 09:19 -0700, Jameson Graef Rollins wrote: > > I run what I imagine is a fairly unusual disk setup on my laptop, > > consisting of: > > > > ssd -> raid1 -> dm-crypt -> lvm -> ext4 > > > > I use the raid1 as a backup. The raid1 operates normally in degraded > > mode. For backups I then hot-add a usb hdd, let the raid1 sync, and > > then fail/remove the external hdd. > > Well, this is not expected to work. Possibly the hot-addition of a disk > with different bio restrictions should be rejected. But I'm not sure, > because it is safe to do that if there is no mounted filesystem or > stacking device on top of the RAID. Hi, Ben. Can you explain why this is not expected to work? Which part exactly is not expected to work and why? > I would recommend using filesystem-level backup (e.g. dirvish or > backuppc). Aside from this bug, if the SSD fails during a RAID resync > you will be left with an inconsistent and therefore useless 'backup'. I appreciate your recommendation, but it doesn't really have anything to do with this bug report. Unless I am doing something that is *expressly* not supposed to work, then it should work, and if it doesn't then it's either a bug or a documentation failure (ie. if this setup is not supposed to work then it should be clearly documented somewhere what exactly the problem is). > The block layer correctly returns an error after logging this message. > If it's due to a read operation, the error should be propagated up to > the application that tried to read. If it's due to a write operation, I > would expect the error to result in the RAID becoming desynchronised. > In some cases it might be propagated to the application that tried to > write. Can you say what is "correct" about the returned error? That's what I'm still not understanding. Why is there an error and what is it coming from? jamie.
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