About the UUID
hi, Philipp.
Now drbd-0.8.x uses UUID instead of GC as the data-relationship-detection -tool, right? Its logic seems clearer than GC. However, I am confused about the UUID in the two-primaries-healedpartition scenario.
Given the original uuids below (both nodes are connected):
P <5,0,0,0> S <5,0,0,0>
then, I plug out the wire of the primary node (disconnected):
P <6,5,0,0> S <5,0,0,0>
I let the downgraded secondary become new primary, UUID should become:
P <6,5,0,0> S <6,5,0,0>
Finally, I recover the wire of primary. And Now, there comes my problem. Accordding to the UUID algorithm, when Cs == Cp, no resynchronisation necessary. However it is obviously split-brain, and drbd ignores it.
Why?
BTW, I did not test such scenario, because I can't compile drbd-0.8.x in my RedHat AS4 distro. I just browsed the doc & code. :-)
Regards,
luo.jinhua
Lars Ellenberg
maintainer/ 2006-12-20 15:06:57 +0800
\ home_king:
Quoted 6 lines
hi, Philipp.
Now drbd-0.8.x uses UUID instead of GC as the data-relationship-detection -tool, right? Its logic seems clearer than GC. However, I am confused about the UUID in the two-primaries-healedpartition scenario.
Quoted 6 lines
Given the original uuids below (both nodes are connected):
P <5,0,0,0> S <5,0,0,0>
then, I plug out the wire of the primary node (disconnected):
P <6,5,0,0> S <5,0,0,0>
I let the downgraded secondary become new primary, UUID should become:
P <6,5,0,0> S <6,5,0,0>
no. these small digits are only more readable examples. our UUIDs are 63bit random numbers.
they may clash, and we have to fix that somewhen. but that is not very likely.
we probably should change the example to read more like head -c8 /dev/urandom | hd
<3cecd7aed66ff5ad,0,0,0> <3cecd7aed66ff5ad,0,0,0>
<dc855810336641b6,3cecd7aed66ff5ad,0,0> <3cecd7aed66ff5ad,0,0,0>
<dc855810336641b6,3cecd7aed66ff5ad,0,0> <44dc24617bd63967,3cecd7aed66ff5ad,0,0>
to make this more obvious.
Quoted 2 lines
BTW, I did not test such scenario, because I can't compile drbd-0.8.x in my RedHat AS4 distro.
works for me.
Signature · 3 lines
: Lars Ellenberg Tel +43-1-8178292-55 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Vivenotgasse 48, A-1120 Vienna/Europe http://www.linbit.com :