Structure of Linux

Here we will be discussing the basics of LINUX, starting with the structure of the OS. The Basic components will be the Kernel, Shell and FHS (Filesystem Hierarchy Standard) . Let’s go through these components in detail..

STRUCTURE

The Kernel

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The Kernel is the Heart of an operating system (OS). Kernel manages everything of a Linux OS. It performs tasks that create and maintain the Linux environment.  It is the communication channel between the hardware and shell. The hardware operations are directed by Shell and are passed through to the right hardware by Kernel.

Structure

SHELL

 

 

Simply put, the shell is a program that takes your commands from the keyboard and gives them to the operating system to perform. . It  is the interface between you and Linux . The commands which we issued , which is interpreted and passed on to the kernel for processing.

 

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There are variable types of shells available in Linux. Most Linux varieties use Bourne-Again shell(bash) but support various others: Korn Shell, Bourne shell, C shell, etc. For all intensive purposes you can just stick with bash but I will show you how to change this if you want to. As you advance you can use shells to create scripts to automate tasks, making your daily routine all the more easier

Filesystem Hierarchy Standard

Linux uses the Filesystem Hierarchy Standard (FHS) file system structure, which defines the names, locations, and permissions for many file types and directories.

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/ – The root directory. Everything in Linux is under root directory. The first stage of Linux filesystem structure.

/bin – Most of the command binary files are under this directory. General commands including ls, man, mv etc… are all under /bin.

/boot – Necessary boot files for Linux are kept under /boot.

 

 

/dev – The device files are located in /dev

/etc – Configuration files are saved under /etc. This directory is just like the control panel for a Windows host.

/home – For all users except the root user, the home directory will be placed in /home. For e.g, /home/beginnersforum.

/media – /media will be used for mounting external storage devices

/mnt – Temporary mounted file systems

/opt — Application programs directory

/sbin — Additional system binaries.

/tmp – As the name indicates, a temporary directory for files.

/usr – The largest directory in Linux. Application files and config files are also kept under here

/var – var stands for variable , that the Variable data on a system. Data that will change as the system is running (Log files, backups, cache, etc.)

/root – Home directory for root as already discussed

This directory structure is everything in Linux.

We can conclude the basic components of Linux here even-though the topic is very deep. More in coming posts. Enjoy reading…!

Basic healthcheck commands for EMC Celerra/VNX

For the Celerra or a VNX file/Unified system we can verify the system health by running the nas_checkup command.  This will do all the checks including the file and block hardware components, configuration checks – NTP, DNS etc…

A sample output is given below,

[[email protected] ~]$ nas_checkup

Check Version:  7.1.72-1 Read more

Check Command:  /nas/bin/nas_checkup
Check Log    :  /nas/log/checkup-run.123456-654321.log

————————————-Checks————————————-
Control Station: Checking statistics groups database………………….. Pass
Control Station: Checking if file system usage is under limit………….. Pass
Control Station: Checking if NAS Storage API is installed correctly…….. Pass
Control Station: Checking if NAS Storage APIs match……………………  N/A
Control Station: Checking if NBS clients are started………………….. Pass
Control Station: Checking if NBS configuration exists…………………. Pass
Control Station: Checking if NBS devices are accessible……………….. Pass
Control Station: Checking if NBS service is started…………………… Pass
Control Station: Checking if PXE service is stopped…………………… Pass
Control Station: Checking if standby is up……………………………  N/A
Control Station: Checking integrity of NASDB…………………………. Pass
Control Station: Checking if primary is active……………………….. Pass
Control Station: Checking all callhome files delivered………………… Pass
Control Station: Checking resolv conf……………………………….. Pass

 


Control Station: Checking if NAS partitions are mounted……………….. Pass
Control Station: Checking ipmi connection……………………………. Pass
Control Station: Checking nas site eventlog configuration……………… Pass
Control Station: Checking nas sys mcd configuration…………………… Pass
Control Station: Checking nas sys eventlog configuration………………. Pass
Control Station: Checking logical volume status………………………. Pass
Control Station: Checking valid nasdb backup files……………………. Pass
Control Station: Checking root disk reserved region…………………… Pass
Control Station: Checking if RDF configuration is valid………………..  N/A
Control Station: Checking if fstab contains duplicate entries………….. Pass
Control Station: Checking if sufficient swap memory available………….. Pass
Control Station: Checking for IP and subnet configuration……………… Pass
Control Station: Checking auto transfer status……………………….. Fail
Control Station: Checking for invalid entries in etc hosts…………….. Pass
Control Station: Checking for correct filesystem mount options…………. Pass
Control Station: Checking the hard drive in the control station………… Pass
Control Station: Checking if Symapi data is present…………………… Pass
Control Station: Checking if Symapi is synced with Storage System………. Pass
Blades         : Checking boot files………………………………… Pass
Blades         : Checking if primary is active……………………….. Pass
Blades         : Checking if root filesystem is too large……………… Pass
Blades         : Checking if root filesystem has enough free space……… Pass
Blades         : Checking network connectivity……………………….. Pass
Blades         : Checking status……………………………………. Pass
Blades         : Checking dart release compatibility………………….. Pass
Blades         : Checking dart version compatibility………………….. Pass
Blades         : Checking server name……………………………….. Pass
Blades         : Checking unique id…………………………………. Pass
Blades         : Checking CIFS file server configuration………………. Pass
Blades         : Checking domain controller connectivity and configuration. Pass
Blades         : Checking DNS connectivity and configuration…………… Pass
Blades         : Checking connectivity to WINS servers………………… Pass
Blades         : Checking I18N mode and unicode translation tables……… Pass
Blades         : Checking connectivity to NTP servers…………………. Warn
Blades         : Checking connectivity to NIS servers…………………. Pass
Blades         : Checking virus checker server configuration…………… Pass
Blades         : Checking if workpart is OK………………………….. Pass
Blades         : Checking if free full dump is available………………. Pass
Blades         : Checking if each primary Blade has standby……………. Pass
Blades         : Checking if Blade parameters use EMC default values……. Info
Blades         : Checking VDM root filesystem space usage………………  N/A
Blades         : Checking if file system usage is under limit………….. Pass
Blades         : Checking slic signature…………………………….. Pass
Storage System : Checking disk emulation type………………………… Pass
Storage System : Checking disk high availability access……………….. Pass
Storage System : Checking disks read cache enabled……………………. Pass
Storage System : Checking disks and storage processors write cache enabled. Pass
Storage System : Checking if FLARE is committed………………………. Pass
Storage System : Checking if FLARE is supported………………………. Pass
Storage System : Checking array model……………………………….. Pass
Storage System : Checking if microcode is supported……………………  N/A
Storage System : Checking no disks or storage processors are failed over… Pass
Storage System : Checking that no disks or storage processors are faulted.. Pass
Storage System : Checking that no hot spares are in use……………….. Warn
Storage System : Checking that no hot spares are rebuilding……………. Warn
Storage System : Checking minimum control lun size……………………. Pass
Storage System : Checking maximum control lun size…………………….  N/A
Storage System : Checking maximum lun address limit…………………… Pass
Storage System : Checking system lun configuration……………………. Pass
Storage System : Checking if storage processors are read cache enabled….. Pass
Storage System : Checking if auto assign are disabled for all luns………  N/A
Storage System : Checking if auto trespass are disabled for all luns…….  N/A
Storage System : Checking storage processor connectivity………………. Pass
Storage System : Checking control lun ownership……………………….  N/A
Storage System : Checking if Fibre Channel zone checker is set up……….  N/A
Storage System : Checking if Fibre Channel zoning is OK………………..  N/A
Storage System : Checking if proxy arp is setup………………………. Pass
Storage System : Checking if Product Serial Number is Correct………….. Pass
Storage System : Checking SPA SPB communication………………………. Pass
Storage System : Checking if secure communications is enabled………….. Pass
Storage System : Checking if backend has mixed disk types……………… Pass
Storage System : Checking for file and block enabler………………….. Pass
Storage System : Checking if nas storage command generates discrepancies… Pass
Storage System : Checking if Repset and CG configuration are consistent…. Pass
Storage System : Checking block operating environment…………………. Pass
Storage System : Checking thin pool usage…………………………….  N/A
Storage System : Checking for domain and federations health on VNX……… Pass

 

 

All the warnings, errors and information will be listed at the  bottom of the output with corrective action if required.

The below commands will help you to collect the necessary information while registering a Service Request etc…

/nas/sbin/model    # to find the VNX/Celerra Model

/nas/sbin/serial    # to find the VNX/Celerra Serial number

nas_server -l       # to list the Data movers and their status.  A sample result is as below.

———————————————–

[email protected] ~]$ nas_server -l

id      type  acl  slot groupID  state  name

1        1    0     2              0    server_2

2        4    0     3              0    server_3

[[email protected] ~]

———————————————–

 /nas/sbin/getreason       # to see the Data movers and Control Station boot status. A sample result is as below.

———————————————–

[[email protected] ~]$ /nas/sbin/getreason

10 – slot_0 primary control station

5 – slot_2 contacted

5 – slot_3 contacted

———————————————–

Control station status should be 10 and Data movers should be 5 with state contacted for a healthy system.

And finally, collecting the logs – the support materials.

/nas/tools/collect_support_materials will help you in collecting the logs. The logs will be saved under /nas/var/emcsupport. The file location and name will be displayed at the bottom of the command output. You can use FTP/SCP tools to copy the file to your desktop.

More in coming posts…

You may refer this post for reading how to collect the SP collects from control station CLI. Hope this post helped you. For more Celerra/VNX posts click here .

 

VNX/Celerra – SP Collects from Control Station command line..

Personally, I prefer Control Station CLI to get the SP Collects for a VNX/Celerra with attached Clariion, quicker..! Opening the Unisphere Manager takes time, of course it is Java enabled. Here let us see how this can be done via the CLI.

Logs.Open an SSH/Telnet session to the control station and login. Read more

You have to navigate to /nas/tools. Basic Linux command “cd /nas/tools” will do this. Once you are in tools, there will be a hidden script get_spcollect which is used to collect the SP Collects (will have to use ls -la for listing it as it is a hidden file).

Now we have to use the below command to execute the script.

./.get_spcollect  [don’t miss the dots before and after the /]

This will run the SPCollects script and gather all the logs and create a single SPCOLLECT.zip file. A sample output will be as below.

 

 

[[email protected]_NAME ~]$ cd /nas/tools/
[[email protected]_NAME tools]$ ./.get_spcollect

Generating spcollect zip file for Clariion(s)

Creating spcollect zip file for the Service Processor SP_A. Please wait…

spcollect started to pull out log files(it will take several minutes)…
Wait until new _data.zip file size becomes final(it will take several minutes)
Retrieving new _data.zip file…
   — truncated output–
Wait until new _data.zip file size becomes final(it will take several minutes)
Retrieving new _data.zip file…
spcollect zip file SYS_SERIAL_SPA_DATE_TIME-STAMP_data.zip for the Service Processor SP_A was created
Creating spcollect zip file for the Service Processor SP_B. Please wait…

spcollect started to pull out log files(it will take several minutes)…
Wait until new _data.zip file size becomes final(it will take several minutes)
Retrieving new _data.zip file…
   — truncated output–
Wait until new _data.zip file size becomes final(it will take several minutes)
Retrieving new _data.zip file…
spcollect zip file SYS_SERIAL_SPB_DATE_TIME-STAMP_data.zip for the Service Processor SP_B was created

Deleting old SPCOLLECT.zip file from /nas/var/log directory…
Old SPCOLLECT.zip deleted
Zipping all spcollect zip files in one SPCOLLECT.zip file and putting it in the /nas/var/log directory…
  adding: SYS_SERIAL_SPA_DATE_TIME-STAMP_data.zip (stored 0%)
  adding: SYS_SERIAL_SPB_DATE_TIME-STAMP_data.zip (stored 0%)
[[email protected]_NAME tools]$

 

 

Now, as mentioned towards the end of the output , the logs – SPCOLLECT.zip will be located at /nas/var/log directory. How can we access it ? I use WinSCP software to collect it via SCP. Enter the IP address/CS name and login credentials. Once the Session is open, navigate to /nas/var/log on the right panel and your required directory on the left. Select the log file and click F5 (or select copy)

WINSCP

 

That’s it..! You have the SPCollects on your desktop. Quite faster , right ? Hope this post helped you. For more Celerra/VNX posts click here

 

Adding custom tabs, groups and commands – Microsoft Excel 2013

Here in this post we are discussing on how to add custom tabs, groups and commands in Microsoft Excel 2013. We may require some commands which are by default are not listed in the default tabs (Here I am taking the option of Macros..).

Excel

Open the Excel 2013 from the start menu. Read more

Select File Menu, then select the Options entry from the listed options (Refer snap below).

Excel-21

 

Options – yes, there are too many options. For this purpose, we have to select the Customize Ribbon option. Here in customize screen you can find the available commands in left and the tabs and groups in right. You can create custom groups by selecting the create group option at the bottom.

Excel-3

 

Excel-5

Here for example, we have created a new tab BEGINNER’S FORUM and a WINDOWS group under it. Also a FORUM-LINUX group under HOME tab. Also we have moved the Macros command under the WINDOWS group.

 

 

Once done, here we can see how it looks like. BEGINNER’S FORUM tab, WINDOWS group and Macros command.

Excel-6

Hope this helped you.

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