Hi David,
Thanks for the info.
Could I assume that if use active/passive multipath with rbd exclusive lock  
then all targets which support rbd(via block) are safe?


发件人:David Disseldorp <dd...@suse.de>
发送时间:2018-03-08 08:47
主题:Re: [ceph-users] iSCSI Multipath (Load Balancing) vs RBD Exclusive Lock
抄送:"Mike Christie"<mchri...@redhat.com>,"Lazuardi 
Nasution"<mrxlazuar...@gmail.com>,"Ceph Users"<ceph-users@lists.ceph.com>

Hi shadowlin, 

On Wed, 7 Mar 2018 23:24:42 +0800, shadow_lin wrote: 

> Is it safe to use active/active multipath If use suse kernel with 
> target_core_rbd? 
> Thanks. 

A cross-gateway failover race-condition similar to what Mike described 
is currently possible with active/active target_core_rbd. It's a corner 
case that is dependent on a client assuming that unacknowledged I/O has 
been implicitly terminated and can be resumed via an alternate path, 
while the original gateway at the same time issues the original request 
such that it reaches the Ceph cluster after differing I/O to the same 
region via the alternate path. 
It's not something that we've observed in the wild, but is nevertheless 
a bug that is being worked on, with a resolution that should also be 
usable for active/active tcmu-runner. 

Cheers, David 
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