Corrupt inittab + HP UX

Hi Friends,

We faced an issue of "corrupt inittab" after five times reboot of machine HP UNIX due to some Hardware issue. Got an opportunity to work with a Senior.

Error :- "Corrupt inittab"

 With this error,
we first thought that do we have an Ignite backup on tape or not,
Second we though can there be an option if we can restore the inittab from other system and use of the same,
Third we thought of checking from point that if our one disk out of mirror is corrupt or if we need to mirror the same.
Fourth :- If we can boot the machine in single user mode.
Fifth :- If we can boot the machine in LVM maintenance mode in hp ux from hpux prompt using "boot vmunix -lm"
and boot the machine.
a. here after boot up in hpux lvm {lvm maintenance mode}, coming to # prompt.Obviously the experience worked.
He copied the inittab file from /usr/newconfig/etc/inittab to /etc/inittab.
b. we were able to copy the first inittab of the server and then copy it on the /etc/inittab.
c. We reboot the system and checked it worked.
d. after reboot, the vgdisplay command showed correct o/p. we checked the same with previous getsysinfo o/p we had in our /tmp location.
e. checked lvdisplay -v "every root lv".
f. this showed stale devices on root lv on one mirrored disk.
g. here we ran, lvsync /dev/vg00/lvol3
h. it started syncing all stale path hanged into current after some time.
i. we took a reboot to confirm and system came up properly. we compared previous outputs and files. they were fine. we restored some part also with latest backup with us.

It was good learning experience, i wish if i can learn more each day.


Love Sharing
Amit Chopra

Linux System working slow after boot up

Hi Friends,

My Linux box is showing %IO wait 50, when i boot it up. But at the same time, when i take a reboot of it, the % IO wait becomes zero and CPU runs fine.

What all can be the issues? please suggest.


Love Sharing
Amit Chopra

HP UX Interview questions Part 5th

Hi Friends,

Got some good questions, which in an interview are most probably asked:-

1. How to replace a root disk, if corrupted or went bad? write down the steps.
2. How to replace a LOCK disk from a running cluster, what are the steps?
3. If all Nodes are in halt state, then what will be the step to remove and add a new lock disk?
4. What can be the minimum and maximum size of a cluster lock disk?
5. Can we reduce an LV without umount in RHEL?
6.  How to extend an LV in Clustered server?
7. What is selinux in HP UX? How can we implement security in HP UX ?
8. Configuring Bonding in HP UX ?
9. how can we make our system secure?
10. What are the ways using which we can increase our booting process faster?

Love Sharing
Amit Chopra

We all have to Save Nature

Hi Friends,

This change in Weather seems an effect of Global Warming, that in the Month of March is having Heavy Rains in plains. Rain is making the Weather cool again and again, it looks like it is delaying the Summers. This is not usual. This change in weather can cause less production of Wheat. Which will directly cause hike in prices of goods and food material. Somewhere i feel it is due to us and we are making the weather and Nature to react in this manner. Nature will try to make its balance and if we do  not support it. then only and only we all living being have to suffer. Like US had heavy snow fall last year i.e. in 2013 due to disturbances in North Pacific (read in some news paper).

"This all shows we are doing very less towards Nature protection, and we are doing very much towards destroying it."

  We all are consuming Natural resources, but not finding alternatives so that those resources can be saved. Even I consider my self I don't know much even how we can save our Nature's Beauty. But listing those Which i have seen some good people doing and learned watching them, I do the following :-

a. I used to switch off my Vehicle at Red light. It is good that we are having timers at our red lights. which helps us to save petrol and save nature as well. saves money as well, "saving money is investing money" Yes this can help a lot when we all come along and do the same practice.
b. Switch off Lights, fans, AC when they are not in use. little contribution if we all do then we can save a lot. doing the same at Office too at my sitting place.
c. Insist my family members to save Electricity and water as much as they can do. Insist on make proper use of Sun light by opening Windows and Doors.

d. Save Rain Water making umbrella or cone shape technique in water tanks.
e. Thinking of implementing Solar Plant at house, it costs around Rupees 35, 000 in total. so that we can save electricity, But waiting too for that, let's Govt. reduce its cost more.
f.  Planting and gardening at Home, tries to make the green home.
g. Save Water by properly tightens the Taps at Bathrooms, Washrooms.
h. Use less water while Shaving, while brushing my teeth.
i. We all try to keep our surroundings near our Home, Office area clean and clear.
j. Try always to through dust in dustbin, instead of throwing it on roads, the same we can try to keep plastic bags, paper bags, Fruit waste, Vegetable waste, Food waste, etc to through it only in Dustbin. This can be kept in mind while driving car, While holiday at Mountains, While roaming outside, while hanging out in market, while going to stadium to play, at each and every place. where we can help area to remain clean and clear.

Yes there can be much, which can be done. need your comments to find more ways towards making our Nature green, clean and healthy for us and our future.

Love Sharing and Love Nature
Amit Chopra

Issues with resetting password of a user and User Management Tips in HP Unix and Red hat linux

Hi Friends,

Today, we faced an issue like, we were resetting the user's password on the server. But every time we were not able to login into the server for some three to four users. the error was "access denied", Yes we had one ID, using that ID we were trying the resetting of password :) .
after trying multiple times even the IDs were locked out, then we unlocked them and reset again. but same access denied message appeared.
then we checked /var/adm/syslog/syslog.log file, there we saw user was getting message of authentication denied with /bin/false. With /bin/false shell the user can be made to never login into the server. and in our case this happened with a tool running at Security Team end. They run a tool which makes server's users login disabled or put the entry in /etc/passwd appending the user's 7th parameter i.e.shell. like it makes the entry :-
#grep ABC /etc/passwd
ABC:x:UID:GID:/home/ABC:System Admimn:/sbin/sh /bin/false
#
then with this the user will not be able to login until we correct it with.

#usermod -s /bin/bash or /sbin/sh ABC
#

after doing this we can login to the server or system.

Things which i have faced for user's access issues, please share with me also if my friends you have. Need to learn more about it.

a. Shell if not properly defined then user faces  an issue in login.
b. if "passwd" after useradd command is not run then user will not be able to login.
c. Account is locked out. unlock the same with :-
#passwd -u ABC

d. Password should have a special character, a number, alphabets CAPS and small combination.

please avoid using easily crackable passwords like :-

a. India@123
b.  Welcome123

etc. , Password should be combination of four things mentioned above.


e. Issue comes in Linux and HP UNIX servers when users do sudo su - and their password has "@" in their password or in root password then the system doesn't accept it and don't allow you to enter complete password.
f. There can be many errors related to AD authentication or NIS or LDAP. So we can discuss those later.
g. You should remember your password, and change the same timely and if its too critical then keep changing the password and weekly or twice a month.
h. Password expire, User expire, Account expires, we can use " chage -l "username" to check this.


There can be and should be many more, will keep sharing and updating. Please share your experience about User's management issues. so that everyone can know and learn.

=====

 #faillog -r

this command is important to be run if we are using trusted system. we can run this command after unlocking or resetting of a user's password.

passwd -u "username"

will unlock the user's password. and to lock it back. we can use below command :-

passwd -l "username"

====

We faced an issue of only one user was not able to login in several other users. I mean to say that all users except one were able to login and we were getting error

"permission denied error on /var/log/btmp"

so checked the permission using :-

ls -ld
getfacl /var/log/btmp

owner should be root and utmp, permission should be  0600 or 0644. Both of these were working. Even after changing the permission that user was not able to login. so we ran faillog -r command after troubleshooting all parameters. 

it worked.

so  before troubleshooting any user related problem, Request to check if the server or system is trusted or not.





Love Sharing
Amit Chopra