Visualization issue in suiquity's zdev activation screen

[Frank Heimes]

When I reach the "Zdev setup" screen, while doing a 20.04 installation on s390x, it happens (from time to time) that - after I've activated zFCP multipath devices - that not all details are properly displayed under the 'zfcp-host' entires.
Please see here:

zFCP devies got enabled, but it looks like that for f10b some devices (sdc and sdd as well as the generic scsi devices sd*) are missing and even the 4th path is not listed at all (but I saw different visualization issues - other devices, only two paths, etc.).

=============================================================
  Zdev setup [ Help ]
=============================================================
  0.0.0400 >
  0.0.0592 >

  qeth
  0.0.0600:0.0.0601:0.0.0602 enc600 >
  0.0.0603:0.0.0604:0.0.0605 >

  dasd-eckd
  0.0.1607 >

  zfcp-host
  0.0.f00b online >
  0x50050763060b16b6:0x4026400600000000 sda sg0
  0x50050763061b16b6:0x4026400600000000 sdb sg1
  0.0.f10b online >
  0x50050763060b16b6:0x4026400600000000 sg2

                                 [ Continue ]
                                 [ Back ]

(The screen is of course fully scrolled down...)

Even pressing F3 / refresh doesn't help -- still the same:

=============================================================
  Zdev setup [ Help ]
=============================================================
  0.0.0400 >
  0.0.0592 >

  qeth
  0.0.0600:0.0.0601:0.0.0602 enc600 >
  0.0.0603:0.0.0604:0.0.0605 >

  dasd-eckd
  0.0.1607 >

  zfcp-host
  0.0.f00b online >
  0x50050763060b16b6:0x4026400600000000 sda sg0
  0x50050763061b16b6:0x4026400600000000 sdb sg1
  0.0.f10b online >
  0x50050763060b16b6:0x4026400600000000 sg2

                                 [ Continue ]
                                 [ Back ]

But going back and forth in the installer steps (and scrolling down):

=============================================================
  Keyboard configuration [ Help ]
=============================================================
  Please select your keyboard layout below, or select "Identify keyboard" to
  detect your layout automatically.

                 Layout: [ English (US) v ]

                Variant: [ English (US) v ]

                             [ Identify keyboard ]

                                 [ Done ]
                                 [ Back ]

... shows all details correctly:

=============================================================
  Zdev setup [ Help ]
=============================================================
  0.0.0592 >

  qeth
  0.0.0600:0.0.0601:0.0.0602 enc600 >
  0.0.0603:0.0.0604:0.0.0605 >

  dasd-eckd
  0.0.1607 >

  zfcp-host
  0.0.f00b online >
  0x50050763060b16b6:0x4026400600000000 sda sg0
  0x50050763061b16b6:0x4026400600000000 sdb sg1
  0.0.f10b online >
  0x50050763060b16b6:0x4026400600000000 sdc sg2
  0x50050763061b16b6:0x4026400600000000 sdd sg3

                                 [ Continue ]
                                 [ Back ]

Hence it's definitely just a visualization problem.
Even just ignoring and proceeding with the installation (w/o going back and forth) is fine and works.

But this can be 'scary' if someone notes during installation that it looks like a path of a multipath device is missing.
Hence I'm reporting this here, but with a low priority ...

[Dimitri John Ledkov (xnox)]

It's not just visualization issue.

Kernel is perfoming asynchronous scan of LUNs without notifing userspace in any way if a scan is in progress, or when it has completed.

Thus when we capture information after zfcp-host device is up, it may have no / some / all LUNs configured already. Note that the listed LUNs are all greyed out, and on this screen one cannot do anything with them. Eventually scan completes, and they are all discovered.

I think we can trigger a full rescan on each zfcp-host activiation, but that will take a long time and lag the UI a lot.

We can trigger and wait for zfcp scan after we exit the screen.

Or we can stop showing the LUNs that becaome available under a given onlined zfcp host.

What would be your preffered options?

ps. no we will not turn-off automatic lun scanning and force people to type every LUN WWID by hand to activate them.

[Dimitri John Ledkov (xnox)]

In terms of installation, we only need one path to a given device to complete the install. Not, all the paths.

[Michael Hudson-Doyle (mwhudson)]

I think we should make the view fully asynchronous, i.e. monitor udev (?) and add / remove rows as devices appear and disappaer, and update the rows as they go on- and off-line. And when a device is activated / deactivated from the menu, we can show a spinner while chzdev is running.

[Frank Heimes (fheimes)]

See LP#1874043 - an update in the underlying framework seems to have fixed not only LP1874043, but also this bug.
Hence closing as Fix Released.