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Showing posts from August, 2014

How to manage RAID in Linux

MDADM
mdadm is a standard software tool to manage RAID in Linux.

to identify a faulty hard disk in a RAID, we can use the command

cat /proc/mdstat

if the raid array is good, we can see the string [UU] . If one of the Disk is failed or faulty, we can see [U_] or [_U]

to mark a disk in RAID as failed:

mdadm --manage /dev/md0 --fail /dev/sdb1

To remove a disk from RAID:

mdadm --manage /dev/md0 --remove /dev/sdb1

To remove the hard disk , we need to identify the failed hard disk physically.
Identifying using the serial number is easy and practical.

To identify the serial number of a hhard disk:

hdparm -I <device> | grep "Serial Number:"

To add a new hard disk to RAID:

a) copy the partition table from existing disk
sfdisk -d /dev/sda | sfdisk /dev/sdb

b) to list the partition table :
fdisk -l

c) add the nee hard disk to RAID:
mdadm --manage /dev/md0 --add /dev/sdb1

d) verify the status of the RAID
cat /proc/mdstat


How to Categorize blogger posts based on subject

Any blogger would like to post about different things in the same blog like me :)
Like a computer engineer may like to write about android programming and something about blogging techniques and something about linux tutorials and something about networking, some interesting photos, etc.

To do this, We can use a Feature called Labels in blogger.

The Labels Option is available in the right side column of the post-editor, like shown in the above picture.
Add Labels GadgetFrom the Blogger Dashboard go to the Layout tab

The layout screen will open.    On it. the Add a Gadget links show you all the places that you can currently add a gadget.

Choose one of these place.

Click the Add a gadget link at the top of the area you choose.
Choose Labels gadget from the list

How to hide Whatsapp photos and videos from Android Gallery

This is a very simple way to hide Whatsapp photos and videos from Android Gallery.

What you need:Any file Manager app. I am using ES File Explorer (https://play.google.com/store/apps/details?id=com.estrongs.android.pop&hl=en)

How to do:

Step 1: Enable "show hidden files option in File Explorer
                how to do this:

a)Click on Settings
b)select display settings c) check " show hidden files" option
Step 2: Copy the file named ".nomedia" from "Profile Pictures" folder Under "Whatsapp" folder
Step 3: Paste the ".nomedia" file into "Whatsapp" folder

Theory:
You can also create an empty file with name ".nomedia" (note the file name begins with '.')
The gallery ignores any folders which contains a file named '.nomedia'