From: Mike Christie <mchristi@redhat.com>
To: target-devel@vger.kernel.org
Subject: Re: tcmu data consistency
Date: Mon, 21 May 2018 19:45:31 +0000 [thread overview]
Message-ID: <5B0321DB.9090906@redhat.com> (raw)
In-Reply-To: <CAF2hZrm9AQtzAFKRk5Z9cbX0KAy7crJp1+RDXJMPUivV19_58Q@mail.gmail.com>
On 05/20/2018 04:10 AM, 亓武强 wrote:
> hi：
> i have some questions about the tcmu, consider following scenario：
>
> 1，Iscsi initiator establishes two session connection with gw1,gw2 at
> the same time. gw1 is the active path.
>
> 2, The active path is switched to gw 2 due to the interruption of the
> connection from the initiator to gw1.
>
> 3, gw2 acquire exclusive lock and write some data to lun0. then gw1
> update the exclusive lock to UNLOCKED.
>
> 4, after step 3, some old iscsi session inflight write ios
> arrival gw1 , gw1 acquire the exclusive lock again, the old data will
> overwrite new data.
With iscsi it should not happen when using explicit failover mode. We
will process all outstanding IO before the STPG, so inflight writes
would be failed then we would grab the lock.
In implicit mode it could happen.
prev parent reply other threads:[~2018-05-21 19:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-20 9:10 tcmu data consistency 亓武强
2018-05-21 19:45 ` Mike Christie [this message]
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