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Let's say I have a 100G disk which i want to expose as an ISCSI-target and I have configured 2-ISCSI-portals(IP1, IP2) which can be used to access the ISCSI-target Note: I have used more than one portal for my High-Availability Use-cases

Let's say, From the Host, I have used IP1 for the login to the ISCSI-Target and am able to connect to the target successfully. After some time Say, because of some reason IP1 is down.is there a config/way to specify the ISCSIADM to fall back to IP2 for connecting to ISCSI-target

Srinivasulu kamavaram
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1 Answers1

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As stark says in the comments above, the answer is to use dm-multipath. There are numerous articles on how to set this up, but the short answer is that it'll likely "just work".

First, install multipathd on your system. Then, when you use iscsiadm in discovery mode, so long as your iSCSI target reports both portals, Linux is going to connect to both portals. You'll get two block devices, both with the same SCSI WWN. Multipathd wakes up, sees the two devices with the same WWN, and bundles them into a /dev/dm-X device for your use. From that point forward, multipathd manages the paths according to how you've configured its policy. The default may be fine for your use.

The key point here is that iscsiadm and iSCSI are kind of "out of the way". You'll have a session for each path. The sessions may come and go. DM-Multipath manages which sessions are involved in providing access to your LUN.

Mike Andrews
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