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Date:      Tue, 24 May 2011 00:09:21 +0300
From:      Toomas Aas <toomas.aas@raad.tartu.ee>
To:        freebsd-scsi@freebsd.org
Subject:   iSCSI multipathing
Message-ID:  <20110524000921.10862o7lpz7ezx8g@webmail.raad.tartu.ee>

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Now that I have basic iSCSI connection working with FreeBSD 7.3  
(thanks Danny!) I'm looking at multipathing. My server has two  
dedicated interfaces for iSCSI traffic, each connected to a separate  
gigabit switch, and each switch in turn connected to a separate  
interface on my iSCSI target (EMC Celerra NX4). I can bring up either  
of the two connections with iscontrol, mount the partition from the  
target and use it to my heart's content. But how should I handle  
multipathing?

My initial thought was to bring up both connections simultaneously and  
set up gmultipath across da0 and da1. However, as soon as I bring up  
both connections, it seems that they begin to constantly disconnecting  
and reconnecting:

# iscontrol -c /etc/iscsi.conf -n celerra_path1
iscontrol[14277]: running
iscontrol[14277]: (pass0:iscsi0:0:0:2):  tagged openings now 0

# iscontrol -c /etc/iscsi.conf -n celerra_path2
iscontrol[14277]: trapped signal 30
trapped signal 30
iscontrol: supervise going down
iscontrol[14277]: sess flags=2000040d
iscontrol[14277]: Reconnect
iscontrol[14309]: running
iscontrol[14309]: (pass1:iscsi1:0:0:2):  tagged openings now 0
iscontrol[14309]: trapped signal 30
trapped signal 30
iscontrol: supervise going down
iscontrol[14309]: sess flags=2000040d
iscontrol[14309]: Reconnect
iscontrol[14277]: trapped signal 30
trapped signal 30
iscontrol: supervise going down
iscontrol[14277]: sess flags=2000040d
iscontrol[14277]: Reconnect
iscontrol[14309]: trapped signal 30
trapped signal 30
iscontrol: supervise going down
iscontrol[14309]: sess flags=2000040d
iscontrol[14309]: Reconnect
iscontrol[14277]: trapped signal 30
trapped signal 30
iscontrol: supervise going down
iscontrol[14277]: sess flags=2000040d
iscontrol[14277]: Reconnect

Is there a way to avoid this constant disconnect/reconnect? How are  
other people handling multipathing on iSCSI?

-- 
Toomas Aas




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