topic Re: vPar boot time in Operating System - HP-UX

vPar boot time

john korterman — Tue, 13 Dec 2005 09:21:02 GMT

Hello Dome experts!

On our new Dome the boot time duration of a vPar surprised me a bit. Situation:

# model
ia64 hp superdome server SD32A

The vPar that was booted was the only running vPar of that nPar.
Before booting was initiated a SG package running in the vPar was stopped.
Only basic hp stuff was running in the vPar.

Action and duration:

From
# shutdown -r 0
until this message:
Rebooting vpar3...press any key within 10 seconds to stop boot
Duration: 3 minutes

From a message stating:
Console is on virtual console
Booting kernel...
until the message:
HP-UX Start-up in progress
Duration: 10 minutes

The rest of the HPUX Start-up
Duration: less than 2 minutes

The 10 minutes for "Booting kernel" was a surprise. Can anyone please tell:
-if this is normal
-why it takes so long
-what the system is doing when "Booting kernel"

Looking forward to hearing from you!
regards,
John K.

Re: vPar boot time

Don Morris_1 — Tue, 13 Dec 2005 12:18:48 GMT

Depends on the system.

What the kernel is doing is initializing itself. The "rest of the start up" is pretty much starting all the processes (system daemons, init scripts, etc.). The core kernel bringup involves figuring out where all the cpus/memory and I/O are and bringing that up.

Usually a long bringup can happen when there's a lot of I/O -- walking the I/O tree to setup all the drivers can take a while. That gets tremendously aggravated if there's a bad terminator on a bus (or something similar) that causes timeouts.

If you've got a lot of memory (256Gb or more) it can take a while to bring up the memory simply because it takes the kernel time to create and initialize the metadata associated with the physical pages so the memory allocation stuff works. The cost is linear -- so more memory == more time.

What's the boot time like for the nPar? If the vPar takes appreciably longer than the nPar then there's definately an issue to be investigated (vPars really shouldn't add much overhead at all and they don't need to do too much [relative to the rest of the kernel] in boot).

Re: vPar boot time

john korterman — Tue, 13 Dec 2005 13:10:55 GMT

Hi Don,

Thank you for your answer.

My understanding of a vPar is as a soft-partition whose hardware is not checked when rebooted alone. Is that wrong?

No indication of HW-errors in dmesg and syslog, but difficult to judge if you do not know what to look for. Any suggestions?

regards,
John K.

Re: vPar boot time

john korterman — Thu, 15 Dec 2005 05:14:36 GMT

Hello again,

still wondering - please share your experience!
What is the average duration for a vPar reboot on your system?

regards,
John K.

Re: vPar boot time

Mark Nieuwboer — Thu, 15 Dec 2005 06:27:51 GMT

Hi john,

It's a few months ago that i booted vpars on a superdome. But it's a lot quicker than from your example. I never had the experince that the booting kernel takes 10 minutes.
Normaly before you know the vpar is up and running in about 5 minutes.

grtz. Mark

Re: vPar boot time

john korterman — Thu, 15 Dec 2005 06:37:16 GMT

Thank you Mark,

do you know what kind of I/O is performed during a vPar reboot, if any?

regards,
John K.

Re: vPar boot time

Mark Nieuwboer — Thu, 15 Dec 2005 07:05:04 GMT

Hi john,

I thougt only the i/o needed by the vpar is loaded.
When booting the npar all the i/o is done.

grtz. Mark