LVM on dmraid breakage

[Luca Berra]

On Wed, Aug 01, 2007 at 04:19:59PM -0400, Phillip Susi wrote:
>I am investigating a bug report involving the combination of lvm and 
>dmraid, and it seems to me that the problem is that lvm is detecting the 
>underlying partition on the primary disk and accessing it directly 
>rather than going through the raid device made by dmraid.  I think that 
>the problem is there is no facility for dmraid to "claim" the physical 
>disk so that lvm does not look at it, and also to have lvm scan the raid 
>device for physical volumes.
>
>Does anyone have any thoughts on how this might be accomplished?

Two things come to mind
1) dmraid should use ioctl BLKPG_DEL_PARTITION, to clean up any eventual
partition table on component devices

2) lvm tool filter could be modified to check if a device has been
already claimed by device-mapper.

something along the lines of:
ioctl DM_LIST_DEVICES
while (...)
  ioctl DM_TABLE_DEPS

the above would probably require a cache.


i believe that manual use of partx or lvm filters is sub-optimal
L.



-- 
Luca Berra -- bluca at comedia.it
        Communication Media & Services S.r.l.
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