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Major number for multipath block devices

DISCUSSION Kumar amit mehta 1 participant 2 messages May 7, 2013

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Hi,

I've a query regarding the major numbers for block devices that the block layer would provide (upon invocation of register_blkdev() with '0' as the major number) for the multipath devices, i.e. If I have one logical volume(Talking in LVM terms)and have two paths to the same logical volume, then it seems that the two logical volumes will have the same major number(refer [1]). I think, to achieve this, dm-mapper would consult with dm-multipath, but I'm finding it difficult to locate this piece of interaction (considering that my assumption is true) between the device mapper layer and the dynamic multipath kernel module. Can someone please educate me here.

[1] http://plone.uconn.edu/Members/jar02014/linux-lvm-and-multipath-configration.

-Amit

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Quoted 3 lines · Kumar amit mehta

If I have one logical volume(Talking in LVM terms)and have two paths to the same logical volume, then it seems that the two logical volumes will have the same major number(refer [1]).

My apologies for typo mistake above. I meant, If I have one logical volume(Talking in LVM terms)and have two paths to the same logical volume, then it seems that, there will be "two" entries under /dev (as we have two paths to the same logical volume) and both these block devices (say, /dev/sdk1, /dev/sdk2) have the same major number, and different minor numbers.