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iLO hard power off

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Tejo Prayaga
Occasional Advisor

iLO hard power off

hi,

We are using iLO v1.89 and server is Proliant DL360 G4p and we run RHEL on this
server.

We have frequently observed that the "power off" operations were taking longer
than "power on". I am assuming that "power off" triggers a graceful OS shutdown,
which contributes to the delay. Please correct me if it is not the case.

However, in some cases it would take much longer to shutdown ( > 20 mins) and we
cnanot determine the exact amount of time a full power off operation takes.

1) Is there any CLI command which does a "hard power off"
After issuing "power off" and waiting for a decent amount of time, and if the
system hasn't brought down yet, we want to issue a hard power off, to forcibly
bring down the system. Is there any command which does this?

2) Is this "hard power off" harmful? What is the best practice and
recommendation here?

I understand that abrupt power offs are harmful and is not a very good thing to
do. What is the recommendation in such kind of situations. Should the
application wait for the OS to completely shutdown (however long it might be) or
wait for decent time and then issue "hard power off"

I have gone through the documentation but could not find any such command.
Appreciate if any one could give some pointers on this. If there is no such
commmand, any alternative approaches could be helpful as well.

Thanks,
Tejo
3 REPLIES
Rob Leadbeater
Honored Contributor
Solution

Re: iLO hard power off

Hi Tejo,

As you've discovered, "power off" from the iLO CLI, simulates a single press of the power button, which in most cases will signal the OS to try and do an orderly shutdown.

If this shutdown is hanging then you can use either "power reset" or "power warm", which do a Cold Reboot or Warm Reboot respectively.

There doesn't appear to be a CLI version of pressing and holding the power button which you can do from the iLO web interface.

As to whether a hard power off is harmful, will really depend on what your server is trying to do when its shutting down. If lots of disk I/O is taking place then you run the risk of getting things corrupted, however if it has just hung with the OS doing nothing then you should be OK...

Hope this helps,

Regards,

Rob
Tejo Prayaga
Occasional Advisor

Re: iLO hard power off

Hi Rob,

Thanks for your detailed response.

I haven't tried the web interface yet. Our application issues CLI commands to
the ILO.

There is a potential problem in case of "power reset". This make the server to
come up again. So, we have to issue a "power off" command after issuing "power
reset", to make sure that the server doesn't come up. If the second command
"power off" fails, or if it is not appropriately timed, it could be ignored.
Probably we should keep issuing "power off" multiple times, until the status has
really changed to "off".

Also, this situation is made compllicated by the fact that the servers are
mostly configured in a PXE boot mode. The server should be made off, before
it comes up and contacts the DHCP server. From the application context, it is
not good if the server comes up again.

Even though this doesn't seem to be a cleaner solution, issuing a "power reset"
followed by "power off" seems to be only option we are left with (at least as far
as CLI is concerned).

It would be very nice if there was a single command which does this.

If there are any other options available, please do let me know.

Thanks for your time.

-Tejo
Rob Leadbeater
Honored Contributor

Re: iLO hard power off

Hi Tejo,

Your servers are attempting to do an orderly shutdown when you hit the power button, or issue a "power off" command from the iLO CLI as they're running ACPI (Advanced Configuration and Power Interface).

To disable this feature on RHEL, you can add the acpi=off to the kernel options.

Edit /boot/grub/grub.conf and add acpi=off to the end of the kernel line - assuming of course you're using GRUB as your bootloader, and then reboot.

I've just tested this on a RHEL4 box and it works fine. As seen as you issue the "power off" command the machine turns off.

One potential downside is that you're more likely to get file system corruption. When the machine does power up again, fsck notices that the machine didn't shutdown cleanly, and waits for 5 seconds for you to hit Y to force a file system check.

Regards,

Rob