QuestionAnswer

Why does the multipath –ll command output not show any devices?

First verify if the devices are discovered or not. The command #cat /proc/scsi/scsi displays all the devices that are already discovered. Then verify the multipath.conf to ensure that it is been updated with proper settings. After this, run multipath. Then run multipath –ll, the new devices should show up.

Why is a newly-mapped LUN not assigned a multipathing device node?

I have no LUNs mapped before. Then I map some LUNs. After running rescan-scsi-bus.sh, LUN 0 doesn’t show up.

I removed a LUN. But the multipathing mapping is still there.

Run rescan_dm_devs in any directory. This should bring up the devices.

Run rescan_dm_devs instead of rescan- scsi-bus for LUN 0 reconfiguration.

The multipathing device is still there after you remove the LUNs. Run multipath –f <device node for the deleted LUN> to remove the multipathing mapping. For example, if device devices related with /dev/dm-1 is deleted, you must run multipath –f /dev/dm-1to remove /dev/dm-1 from DM mapping table. If multipathing daemon is stopped/restarted, run multipath –Fto flush out all stale mappings.

Failback does not happen as expected with the array.

Sometimes the low level driver cannot auto- detect devices coming back with the array. Run rescan_dm_devs to rescan host server SCSI bus and re-aggregate devices at multipathing layer.

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Configuration: Device Mapper Multipath for Linux

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Dell MD3220i, MD3200i owner manual 186, QuestionAnswer
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MD3200i, MD3220i specifications

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