I'm trying to debug something related to iSCSI LUN resizing.
In our setup we use Debian Linux 8 (jessie) with Open-iSCSI and multipath-tools connected to a FAS2552 (ONTAP 8.3.2RC2) device.
When we resized our LUN from 6 TiB to 14 TiB yesterday some of the paths got in a weird state.
We noticed that the iSCSI clients (the Debian machines) detect the resize:
kernel: [5606835.845712] sd 1:0:0:0: Capacity data has changed kernel: [5606842.329394] sd 2:0:0:1: Capacity data has changed
This is detected because the FAS2552 device is reporting this via iSCSI ("2A 09 CAPACITY DATA HAS CHANGED").
For some reason we got in this situation:
$ multipath -l ... size=14T features='4 queue_if_no_path pg_init_retries 50 retain_attached_hw_handle' hwhandler='1 alua' wp=rw |-+- policy='service-time 0' prio=0 status=active | `- 3:0:0:0 sdc 8:32 active undef running `-+- policy='service-time 0' prio=0 status=enabled `- #:#:#:# - #:# active undef running
I'm trying to reproduce this issue by creating a new 50G LUN and resizing the LUN, but the "Capacity data has changed" logline doesn't appear in our logs when we execute the resize.
In which case does a FAS2552 device report a resize of a LUN exactly? Or in other words, why doen't it report the resize on my 2nd LUN as it did on my 1st yesterday?