Starting ...... Currently no name

I am not a writer .  But whenever i get time, i try to pen down something  . Normally will try to post the technical stuffs ,but  first time tried to  write something new .


So please comment  if you like and provide suggestions to improve it


Synopsis
========

This story revolves around an engineer kumar  .   This is the first part  In This part , I had tried express , the  first day of the  engineering college life of kumar .
There are many interesting incidents that can be penned down .   


Part-1 

It was month of May , sun was on top  with the temperature about 40 degrees but the thinking mind kept me distracted from the sweat on my neck and the sticky humidity of the day.
I booked the auto and started toward the Engineering college.

Me: how far is the college ?
auto driver:  it is 8 Kms outside the city .

There was complete silence  ,as we were nearing , i was  enjoying the   lush green fields, grazing  cattles and  small dhabas  ,which i saw after long time .
 
auto driver: this is the college entrance gate .
Me: thanks how much?
auto driver: 40 Rs
Me : this is your's 40 rs ,thanks

Scene-1 - Entry to College

I started moving slowly toward the entry gate thinking about hostel,ragging ,colleauges and bla bla bla ,when i heard somebody calling me .
it was the  security  gate personnel  .

security : hey come here
Me: Yes plzz
security : New admission
Me : yes. can you please let me know the  principal's office
security :  Please make the entry in the register . Go straight on right there is principal's office .

I entered the college gate ,started for principal's office .It was a big campus,Its shady trees ,green sunny lawns, row of roses  catched my eyes .The cold air started  blushing giving  the cooling sensation .

I saw a group of students sitting on the corridor .

Me: Hi kumar here , shall i know where is the pricipal's office
senior: go straight the last room .
Me: Thanks
senior (laughing) : will see you soon .
I reached the principal office , and knocked the Door
principal : come in
Me: thanks
Principal: Take your seat
Me: okay thanks sir
The dicussion started with the  introduction,expectections ,curriculum  then it came to hostel.
Principal: You have opted for hostel .
Me: yes
Principal: Will call the hostel warden to discuss the room allocation .
Me: Okay ,thanks sir
Principal: He will be here in 5 minutes .

Hostel warden enters the principal office and greets
Warden: Good afternoon sir
Principal : Good Afternoon. Meet kumar he has joined today and will be needing your's help.
Me: Good Afternoon
Warden : Are you new joinee .
Me: yes
Warden: there are 5 rooms free in the hostel , 4 in first floor and 1 in ground floor and all are twin sharing .
Me: ground floor will be fine for me .
Warden : write down the hostel address and the room number in the notepad .
Me: okay thanks sir

I left the principal's office and the saw the watch , it was 3 PM  and i was  hungry  and
I went nearly local dhaba  and took some food and took auto for the hostel  and reached the hostel entrance gate .

Scene-2 - Entry to Hostel

Security : Good evng
Me: Good evng and handed over  the note .
Security : welcome
Me : Thanks
Security : please come with me .

We started moving toward the hostel corridor  and finally reached the allocated room.

Security : This is the room  who had been allocated .
Me: thanks

I threw all  my luggage and locked the room and went to take the much needed shower  and after that went to the bed , I don't know when my eyes grow heavy and i  went into deep sleep . sudden knock , i woke up  and opened the door .

Me :  Hi good evng
pandey : HI , i am pandey .
Me: Good evng , kumar here ,i have newly joined .
Pandey : ohh.. okay .. Good evng mate
Me: How is the hostel .
Pandey : fine
Me: heard about ragging ,  is it here also ?
Pandey (laughing) : You will come to know in few days.
Me : Please tell me have you faced it here?
Pandey: Yes , nothing to worry ..
Me:   Can you let me know what i should be doing as you are in hostel for few days
Pandey : sure , Don't look into the eyes of any seniors ,greet them whenever you see and obey the instructions , rest all will be fine .
Me: thanks will do that .

It was around 8 PM , we started towards canteen for food . There i met few more colleagues and  introduced myself .  My eyes were searching for any  known face then  Suddenly saw singhji one of my schoolmate  , i smiled and went towards him .


Me : singhji you here
Singhji : Kumar how r u ?
Me: good  after long time . wht abt you ?
Singhji : i am fine . Nice seeing you ..
Me: Singhji in which room you are staying ?
Singhji: S-12
Me: ok .. we have lot to talk ,we will sit together after food
Singhji: Ok kumar
Me: Pandey , at what time you go to bed?
Pandey : 11 PM.
Me: ok ,will go with singhji and comeback before 11.

We completed our food while talking and i went with singhji to his room .There in his room already many of our colleagues were sitting and playing cards .


Singhji: Meet my old friend and our class mate .
Me: Good evng friends .
Singhji : kumar consider it as your room and take the seat .
Me: thanks singhji
Singhji : This is our normal timepass that we  normally  do after  college timings.After college ,if we are going out o hostels seniors will catch.
Basker: Do you know how to play cards.
Me: yes
Basker: we are playing dahla pakad(card game) ,would you like to join us .
Me: thanks ,yes will .

we started playing the game and there was complete silence and everybody was concentrated  as the last phase was coming .

suddenly anurag(one of the colleague ) entered with the bang .
Anurag:  Basker,singhji how r u ?
Singhji : fine ,meet my old friend kumar who joined us today .
Anurag : Hi  kumar , how  r u ?
Me: fine
Anurag : which branch
Me: Computer science
Anurag: Playing Cards  mates , This room has become  the adda for cards .
Basker : Yes sirji , you can join us .

After 20 mins ,there was knock on the door and 3-4 people came inside the rooms , with cigarettes in their hands,eyes complete red  and the unpleasant smell of alcohol spread across the room .
. Everybody left the cards and stood up and greeted with heads down.

Senior : Hey what you all were doing ?
Basker : Sir ,we were playing cards. would you like to join us .
Senior : New bakra (joinee) ..looking at me .
Me: Yes sir
Senior: Give your intro
Me:  .......................
Senior : Sing a song for me ?
Me : started singing .. ratkali ek khwab me aayi ..
Senior : Shit .. can you sing any new song
Me : tujhe dekha to yeh jaana sanam....

Senior : Basker  you dance the nagin dance ,on this song . kumar you should not stop  singing before 5 mins.I started singing ,basker started rolling the hands like cobra ..hiss ..hiss.. and expression  everybody started laughing ,i too .

Senior(anger) : kumar how  dare you stopped before 5 mins ?
Senior : bend on your knees and be there until i tell .
Me : ok sir
Senior: now we will have the cricket match here . Basker you will be batting , anurag you will be bowling and kumar you need to do commentry .
Me: Ok sir
Me: Gayle is getting ready to face the first  ball from prasad.  Prasad is running from the stadium end  and gayle played  the defensive shot .
Senior : Idiot.. i told Basker is baating and anurag is bowling ... where comes the  gayle and prasad .
Me: sorry sir , you told to do commentry ,that only was doing .
Senior : Singh can you give a slap to kumar
Singhji : ok sir.
Senior : is this slapping , shall i teach you how to slap.
Singhji : No sir .. slapped
senior: how you felt,was it fine or you require more.
Me:(rolling hands on the cheeks) : it was hard.. will start the commentry
Me: basker on the crease to take strike  of the first ball from anurag .basker hits the ball to the short fine leg boundary ..fielders running behind ,but looks like it ball will
reach the boundary and it is . Anurag bowls the second delivery which was fullish length  ,basker defends.

it goes on for next 5 mins

Senior : ok guys ,we are feeling sleepy ... see you tommorrow ..gud ngt..


This is how  was the first day of the  kumar's  engineering life


to be continued ..............................

 Many more to come ..

Please comment if you like .. 

OPENSSH 7.1 (7.1.102.1100) -- issues

OPENSSH 7.1 (7.1.102.1100)  .

1.       Addition of ciphers  using “+” sign

After adding below lines in sshd_config

Ciphers  + blowfish-cbc,arcfour256,arcfour128

#ssh -vv test123

debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctrchacha20-poly1305@openssh.com,,blowfish-cbc,arcfour256,arcfour128

debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctrchacha20-poly1305@openssh.com,,blowfish-cbc,arcfour256,arcfour128

      The issue seems to be with the double comma , that prevents  the ciphers to work .

2.       The unsupported Ciphers  showing in the OPENSSH package itself

List of supported Ciphers in OPENSSH7.1 Package

$ssh -Q cipher

3des-cbc

blowfish-cbc

cast128-cbc

arcfour

arcfour128

arcfour256

aes128-cbc

aes192-cbc

aes256-cbc

rijndael-cbc@lysator.liu.se

aes128-ctr

aes192-ctr

aes256-ctr

chacha20-poly1305@openssh.com

As per the sshd_config Man page , The default Cipher List .

chacha20-poly1305@openssh.com, aes128-ctr,aes192-ctr,aes256-ctr, aes256-gcm@openssh.com 

Connectivity result before applying the Ciphers

$ ssh -vv test123

debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctrchacha20-poly1305@openssh.com, >>>List of ciphers supported by default by OPENSSH7.1

debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctrchacha20-poly1305@openssh.com,

It refers to me that the default Cipher that the OPENSSH7.1  supports  is something different that we see in the man page of sshd_config .  “aes256-gcm@openssh.com” cipher doesn’t exists in the default Cipher list,  when we do connectivity test .  

Below Ciphers list were added  as per the different site references  .

Ciphers blowfish-cbc,aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,chacha20-poly1305@openssh.com,aes128-gcm@openssh.com,aes256-gcm@openssh.com

Working Configuration

But when we tried this options after removing the gcm cipher , it worked .

Ciphers aes128-ctr,aes192-ctr,aes256-ctr,chacha20-poly1305@openssh.com,aes256-cbc,3des-cbc

Common errors :

Unable to negotiate with x.x.x.x.: no matching cipher found. Their offer: aes128-cbc,blowfish-cbc,3des-cbc lost connection

solution ) add the below lines in sshd_config configuration file 

Ciphers aes128-ctr,aes192-ctr,aes256-ctr,chacha20-poly1305@openssh.com,aes256-cbc,3des-cbc.blowfish-cbc

stop and start  the ssh services 

 error 2) sometimes noticed that passwordless authentication or the authentication negotiations are happening using only  the dsa keys , then it will fail ?
ans) in openssh7 ,the dsa keys are by default disabled , it means that any key negotiations or connections that uses only dsa keys will be failing . In this scenario , we need to first validate the connectivity using the ssh -vv  <server-name>  check for the keys which it is accepting   to confirm the exact issue . 

add the below lines in sshd_config to allow the dsa keys . 

HostKeyAlgorithms +ssh-dss 

PubkeyAcceptedKeyTypes +ssh-dss 

stop and start the sshd services . 

test the connectivity . 

AIX - CPU Utilization -Some points

                                        CPU Utilization in AIX . 
                                      =====================

 Here in  our example , we will try to understand actually how are the CPU entitlement parameters working in AIX .

 Let us  try to understand through different scenario's .

 Taking the below example 


 Mode                                           : Uncapped
Entitled Capacity                          : 3.00
Online Virtual CPUs                     : 20
Maximum Virtual CPUs                : 30
Minimum Virtual CPUs                 : 2
Minimum Capacity                        : 1.00
Maximum Capacity                       : 10.00


 Entitled Capacity : This LPAR is entitled/guaranteed  to get 3 CPU .
Minimum Capacity :  minimum requirement to start this LPAR is 1 CPU .
Maximum Capacity : Maximum entitlement for this LPAR is 10 CPU .

Question comes here .,what is actually maximum Capacity and how it works ?
ans) Maximum Capacity parameter comes into picture when we talk about DLPAR operations . It means that we can increase the  Entitled Capacity  online to the Maximim Capacity Value i.e. in this scenario to 10 . 
                                  Maximum entitlement doesn't have any relation with the CPU utilization  of LPAR . Many times noticed people have mis-conception that this is the maximum value till what CPU utilization of the LPAR can go .

Ques) In this scenario ,what can be the maximum CPU utilization this LPAR can achieve ?
ans) This LPAR is un-capped ,it means that it  can go upto maximum limit as per the configuration and requirement  subjected to the fact that CPU pools are having enough free CPU.
     When we talk about it can go to maximum limit  as per the configuration ,here comes into the picture the "online virtual CPU "  .As we know that , virtual CPU use power of 1 CPU as per the requirement .     The maximum  CPU utilization of this LPAR depends on the value of "online virtual CPU's "  and the free CPU's available in CPU Pools.
Here in this scenario , This LPAR  CPU utilization can go  maximum  upto 20 CPU   subjected to the fact that it that enough CPU resources in the CPU Pool .


Taking the same scenario but the "CPU Mode is capped"


Mode                                            : capped
Entitled Capacity                          : 3.00
Online Virtual CPUs                     : 20
Maximum Virtual CPUs                : 30
Minimum Virtual CPUs                 : 2
Minimum Capacity                         : 1.00
Maximum Capacity                        : 10.00



Ques) In this scenario ,what can be the maximum CPU utilization this LPAR can achieve ?
ans) The CPU mode for this LPAR is capped means that in any case it can't go above the entitled Capacity . Here in this case , Entitled Capacity is 3 CPU , means  CPU utilization
 of this LPAR can't go beyond 3 CPU . 

NMON- Analyzing Memory Usage

Recently, got request to clarify the  AIX Memory utilization from application team  . After going through lot of documentations , this was what i was able to understand .  .  

Total virtual :36 GB  >>>  this total memory allocated which includes physical and paging space .

Accessed virtual : 16.3 GB --   Active virtual pages  in memory (including pagespace + real memory) which comes around 45.3%

In AIX  Virtual Memory Management  , The free memory will be used for cache and whenever application request for memory , it will freed automatically .  

In our latest report below is the physical memory consumption .

%used =93.7%   -- it is the total  physical memory used out of 32 GB (i.e process+system +cache)

Note:  This will be always high  in AIX  as it includes the cache also .

%free =  6.3%

This section  of NMON provides details how is the physical memory used  and the differentiation –refer below attached screenshot  .

Numperm(cache) =41.9%      >>> this is used for cache purpose(filesystemcache etc)  for better performance and will be freed up automatically by the Operating system when application requests for memory.

Process                = 40.4%      >>> this much of physical memory out of 32 GB is used by application process

System                = 11.4%      >>>  This much of memory is used by the Operating system processes out of 32 GB

Free                    =6.3%         >>>  This is free physical memory available out of 32 GB

Basically when we talk about performance we consider only “process+system”  . If this is above 90 -95% , then we can see performance impact .