Sys1.Nucleus.

[Viswanathchandru]

Dear all,

I was reading the manual on the NIP process during the IPL. A quick question came to my mind. Probably a wired or worst question. I have a scenario like this(Imagine) I have my system up and running. And by mistake some one have deleted the sys1.lpalib and the sys1.nucleus and sys1.linklib. (I didnt mean to delete it either and i don't even want to imagine such a scary scenario still,) what will happen to the system. Will the system continue to operate? or Will it come down. Please I never mean it to delete. I just want to know what could be the impact of the system the moment it gets deleted. Ofcourse, I can understand i should have to struggle for the life time to bring the system up when I do an IPL after this disaster. Please throw some light on this. Apologize a ton If i or my thoughts are wrong!!


Regards,
Viswa

[Robert Sample]

This is an EXTREMELY theoretical question, and I'm not sure you could ever get a complete answer -- especially since the answer most likely depends to some degree upon site set up. First, it is not that easy to delete those files, especially in a sysplex. To delete SYS1.LINKLIB, for example, you would have to deactivate the linklist in every LPAR in the sysplex. Hence, you are asking about something that could not be done accidentally. Second, remember what the linklist and LPA are -- programs loaded into memory so they don't need access to disk to be able to execute. However, no matter whether or not the system continued running in such a scenario, I suspect it would not run for long -- but this is NOT a test I would run myself!

[Viswanathchandru]

Hello Robert!

I had my eyes wide open, to see someone addressing this post! Thanks a lot for addressing!

Robert wrote: remember what the linklist and LPA are -- programs loaded into memory so they don't need access to disk to be able to execute. However, no matter whether or not the system continued running in such a scenario, I suspect it would not run for long

I totally agree!!!!


But one thing still I am not able to understand is what is the use of sys1.nucleus. Is this module required for the continual system operation like some of the system programs do a fetch of modules from this dataset or its required only during the IPL for the system core to get build. If its only for the system core to get build I should not be facing any problem still the system is IPL'ed for the next time. Apologize if i'm wrong!!

Regards,
Viswa

[Robert Sample]

When we mention "z/OS", much of what we are talking about is the operating system code stored in SYS1.NUCLEUS. From the manual z/OS system installation and maintenance (http://publib.boulder.ibm.com/infocente ... raries.htm):

SYS1.NUCLEUS
SYS1.NUCLEUS contains the basic supervisor modules of the system.

[enrico-sorichetti]

if You want to know what happens to Your system when You delete the SYS1.NUCLEUS dataset

just open the
z/OS V1R10.0 MVS System Codes
http://publibz.boulder.ibm.com/cgi-bin/ ... 0112020001
(*) not the latest one but more than enough to satisfy Your curiosity
and search for SYS1.NUCLEUS
it will show all the system wait state codes related to SYS1.NUCLEUS misfortunes

[nevilh]

To delete SYS1.LINKLIB, for example, you would have to deactivate the linklist in every LPAR in the sysplex.

No longer required assuming dataset is not sms managed. Dataset can be renamed and deleted assuming one has the required level of authorisation.