Oracle VM: Guest VM Shows Unlikely iostat(1) I/O Statistics After Live Migration

(Doc ID 2013372.1)

Last updated on MAY 28, 2015

Applies to:

Oracle VM - Version 3.2.4 and later
Information in this document applies to any platform.

Symptoms

After a successful live migration, a guest virtual machine (VM) shows an unusual I/O utilization. The iostat(1) tool run inside the VM shows a display similar to:

zzz ***Mon Feb 23 23:55:05 CET 2015
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.52    0.00    1.55    0.52    0.00   97.41

Device:         rrqm/s   wrqm/s   r/s   w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
xvdb              0.00     0.00  0.00  0.00     0.00     0.00     0.00    16.00    0.00   0.00 100.00
xvdb1             0.00     0.00  0.00  0.00     0.00     0.00     0.00    16.00    0.00   0.00 100.00

In this example, the block devices report 100% utilization but no I/O operations are being performed.

Changes

 A VM guest using a UEK kernel was live migrated.

Cause

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