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Re: Periodical reboot of the servers

 
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Shivkumar
Super Advisor

Periodical reboot of the servers

Dear Sirs,

I was told by someone that HPUX unix servers needs to be rebooted periodically. I also read that IBM AIX needs reboot periodically for better performance.

I am not sure why and when it should be rebooted. Is there any way to find out when we need to reboot the servers ?

Thanks,
Shiv
17 REPLIES 17
Sudeesh
Respected Contributor

Re: Periodical reboot of the servers

It depends on the application running. If lot of memory leak is there I would suggest you reboot the machine periodically. Otherwise reboot during the quarterly pathching will also serve the purpose.


Sudeesh
The most predictable thing in life is its unpredictability
Devender Khatana
Honored Contributor
Solution

Re: Periodical reboot of the servers

Hi Shiv,

This formula does not apply on HPUx or even on hardware supporting HPUx. I have around 30 odd HPUx PA-RISC servers and the uptime for these is listed here

*************************************
COMMAND : uptime
*************************************

10:23am up 77 days, 10:23, 6 users, load average: 0.07, 0.06, 0.05
10:23am up 49 days, 10:10, 0 users, load average: 0.11, 0.08, 0.04
10:23am up 9:26, 4 users, load average: 0.11, 0.11, 0.10
10:23am up 84 days, 23:52, 6 users, load average: 0.01, 0.01, 0.01
10:23am up 104 days, 15:35, 3 users, load average: 0.12, 0.06, 0.05
10:23am up 104 days, 15:38, 0 users, load average: 0.03, 0.04, 0.06
10:23am up 104 days, 15:38, 0 users, load average: 0.02, 0.01, 0.01
10:23am up 104 days, 15:38, 0 users, load average: 0.01, 0.02, 0.02
10:23am up 104 days, 15:38, 0 users, load average: 0.03, 0.04, 0.04
10:23am up 104 days, 15:38, 0 users, load average: 0.02, 0.03, 0.03
10:23am up 104 days, 15:38, 0 users, load average: 0.16, 0.08, 0.05
10:23am up 104 days, 15:38, 0 users, load average: 0.01, 0.01, 0.02
10:23am up 64 days, 11:23, 0 users, load average: 0.00, 0.01, 0.02
10:23am up 119 days, 10:23, 0 users, load average: 0.01, 0.03, 0.03
10:23am up 119 days, 10:16, 0 users, load average: 0.02, 0.01, 0.02
10:23am up 119 days, 10:14, 0 users, load average: 0.05, 0.03, 0.03
10:23am up 119 days, 10:14, 0 users, load average: 0.04, 0.05, 0.04
10:23am up 119 days, 10:11, 0 users, load average: 0.03, 0.04, 0.06
10:23am up 119 days, 10:10, 0 users, load average: 0.01, 0.02, 0.02
10:23am up 119 days, 10:09, 0 users, load average: 0.02, 0.03, 0.02
10:23am up 119 days, 10:09, 0 users, load average: 0.01, 0.02, 0.01
10:23am up 119 days, 10:11, 0 users, load average: 0.02, 0.02, 0.02
10:23am up 100 days, 19:01, 0 users, load average: 0.00, 0.00, 0.00
10:23am up 119 days, 9:56, 0 users, load average: 0.03, 0.03, 0.02

There has been only one or two instances during this time that application was shut that too was done manually for changes.

HTH,
Devender
Impossible itself mentions "I m possible"
Mahesh Kumar Malik
Honored Contributor

Re: Periodical reboot of the servers

Hi Shiv

There is no set rule for hp-ux servers to be rebooted. It depends on application environment. If there are memory leaks and number of sleeping processes are on rise, reboot is recommended.

Regards
Mahesh
Bill Hassell
Honored Contributor

Re: Periodical reboot of the servers

You were misinformed. Properly patched HP-UX is extremely stable and can run for years without a reboot. As mentioned, the problems are with bad application programs but even these can be fixed by restarting the apps, not rebooting. The ONLY reason to reboot is to perform kernel patches, perhaps 2-3 times each year.


Bill Hassell, sysadmin
Steven E. Protter
Exalted Contributor

Re: Periodical reboot of the servers

The only thing I ever rebooted my servers for was patches and security updates.

Nothing else.

No need to do it. Since I patched once a quarter, thats how often I booted them.

SEP
Steven E Protter
Owner of ISN Corporation
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Babu A
Frequent Advisor

Re: Periodical reboot of the servers

Hi Shiv,

There is no hard rule for rebooting. The info was not true. I have servers running for more than 400 days without a reboot. All we need to do is keep monitoring it.

Example of server which is being running for the past 401 days.

4:38pm up 401 days, 7:49, 1 user, load average: 0.00, 0.01, 0.01

Regards,

Babu
Shivkumar
Super Advisor

Re: Periodical reboot of the servers

Are more number of sleeping processes harmful ?

So is reboot only option left to resolve this ?

Thanks,
Shiv
Babu A
Frequent Advisor

Re: Periodical reboot of the servers

Hi Shiv,

You may kill the sleeping processes, but may not be able to kill all the Zombie processes. To kill all zombie process we need to reboot the server.

Below is the explanation of Zombie process.

Zombie processes are created when the parent process either does not
wait on the child process, or does not ignore the child's termination
by setting the 'SIGCLD, SIG_IGN' signal within their program. Zombies
remain until the parent exits. Although zombies do not use CPU time,
they do occupy a slot in the process table.

Zombie processes are also created when a child process completes, and
sends a termination to the parent, before the parent receives the
'SIG_IGN, SIGCLD' signal to ignore the termination.

These processes cannot be killed, as they are already dead. If the
parent is killed before it exits properly, and cleans up any zombie
child processes, only a reboot will clear the zombies from the system

Regards,

Babu
A. Clay Stephenson
Acclaimed Contributor

Re: Periodical reboot of the servers

Zombies consume no resources (other than a slot in the process table) so as long as you are well below nproc there is absolutely no harm in them. Rebooting to clear zombies is really a Mickey Mouse solution; the real answer is to find out why you have then in the first place and thus fix the cause rather than treating the symptoms.

HP-UX boxes are typically up for months without reboot and the only time they should be rebooted is for periodic patchset installation.
If it ain't broke, I can fix that.