Solaris OS temporarily suspends I/O traffic (I/O stall) to all logical units on both Dell EMC Unity Storage Processors when one of the Unity Storage Processors is rebooted or placed to Service Mode (Doc ID 2860570.1)

Last updated on APRIL 27, 2022

Applies to:

Symptoms

If one of the EMC Unity Storage Processors (SP) is rebooted or placed to Service Mode, the EMC Unity storage performs SP failover and tries to transition the I/O traffic to the remaining SP. However, Solaris OS may temporarily suspend I/O traffic to _all_ logical units on both EMC Unity Storage Processors.

If this issue occurs, an example from iostat:

The length of the I/O stall depends on if FC switch is used or not, if FC switch is used, the I/O stall takes approx. 20 seconds.
If FC switch is not used, the I/O stall takes approx. 80 seconds.

Cause

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