[Bug 1882986] Re: open-iscsi is slowing down the boot process

[Zakhar]

You're welcome.

Indeed, at first I though it was Virtualbox that has no .service (just a
SystemV classic init) but changing that had no effect, and disabling
iscsi gave me back my 10 seconds !

systemd-analyze:

summary: without iscsi

Startup finished in 17.404s (firmware) + 3.367s (loader) + 2.386s (kernel) + 23.669s (userspace) = 46.828s 
graphical.target reached after 23.656s in userspace


summary: with iscsi

Startup finished in 13.841s (firmware) + 3.360s (loader) + 2.272s (kernel) + 31.785s (userspace) = 51.260s 
graphical.target reached after 31.775s in userspace

(And you note the "firmware" was quicker since it is a "reboot", the
first one is a cold boot, and needs to wait for the spinning disks to
spin!)


As attachment, you have the full dumps.
I'm not yet enough at ease with SystemD algorithm to spot at first sight nasty dependencies!


** Attachment added: "systemd-analyze dump (with iscsi services DISABLED)"
   https://bugs.launchpad.net/ubuntu/+source/open-iscsi/+bug/1882986/+attachment/5383002/+files/no_iscsi.txt

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https://bugs.launchpad.net/bugs/1882986

Title:
  open-iscsi is slowing down the boot process

Status in open-iscsi package in Ubuntu:
  Triaged

Bug description:
  This is not a bug, but rather an "optimisation" request.

  (Probably set this as "enhancement request" + Low)

  Apparently, the package is assuming the user will need some iscsi
  mounts for his session, and is putting dependencies in the systemd
  services/targets which effects are to delay "graphical.target" to
  after the point when the network is online.

  A great job has been done by Ubuntu so that the O.S. appears to be
  "snappy" from the boot, and when the session is in "auto-login", it
  really makes a great difference and a good feeling of the system being
  very quick.

  This assumption of open-iscsi sort of ruins that effort.

  As an example, on my PC the graphical target is delayed 10 seconds
  more (was 22 seconds and is now 32). The impression is not as good and
  the system feels "slow again" (although it is just a feeling!)

  
  Step to reproduced (you don't even need to have iscsi LUNs to to so, just install the package!)
  - Start from a clean 20.04, boot up and issue: systemd-analyze
  - Now install open-iscsi, reboot and issue again: systemd-analyze

  The result will probably be a big impact on "graphical target",
  although total time does not change a lot.


  My usage is not needing iscsi targets for my session.
  I have a NAS with iscsi LUNs, and when I need those mounts, I just start them with a command.

  sudo iscsiadm -m node -l

  Then Gnome recognises a new disk has been inserted and does an "auto mount".
  This command works whether the service was started or not.


  This wrong assumption is easily fixed in my case with this command:

  
  sudo systemctl disable iscsid.socket iscsid.service open-iscsi.service

  
  Then, at the next reboot the graphical target is snappy again, and does not have to wait for network-online and remote-fs targets.


  I don't know what can be done to cope with both situations : those who
  need an iscsi target mounted for their session, and those who don't...
  but I guess the philosophy now should be to assume the user does not
  need such targets, and don't put dependencies that delay the snappy
  boot process.

  For those who need those mounted remote fs for their session, detailed
  help on how to enable iscsi services at startup should be provided.

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