Cloud Vedas

Solved: How to take XSCF snapshot of M-Series server running Solaris

In this post we will see how to take XSCF snapshot of an M-Series server

Save snapshot on different server

First create a user "test" in OS of server in which you want to save snapshot.
Next login to XSCF of server whose snapshot you want to take.
Take snapshot by giving IP of destination server on which you want to save the data using the below syntax.
```
snapshot -LF -t username@serverip:/full_path_to_data_location -k download
```

Here is an example. We created test user in 192.168.99.10 destination server, and snapshot will be saved in it's /var/tmp directory.

XSCF> snapshot -LF -t test@192.168.99.10:/var/tmp -k download

Save snapshot on same server.

If you want to save snapshot on same server of which you are collecting snapshot use below steps.

XSCF> showdscp

DSCP Configuration:

Network: 10.1.1.0
Netmask: 255.255.255.0

Location Address
---------- ---------
XSCF 10.1.1.1
Domain #00 10.1.1.2
Domain #01 10.1.1.3
Domain #02 10.1.1.4
Domain #03 10.1.1.5

Check the running domain

XSCF> showdomainstatus -a
DID Domain Status
00 Running
01 -
02 -
03 -

Ping to ensure you can connect to the network

XSCF> ping 10.1.1.2

PING 10.1.1.2 (10.1.1.2): 56 data bytes
64 bytes from 10.1.1.2: icmp_seq=0 ttl=255 time=2.1 ms
64 bytes from 10.1.1.2: icmp_seq=1 ttl=255 time=2.0 ms

Take snapshot after creating a user on the OS.

XSCF> snapshot -LF -t test@10.1.1.2:/var/tmp -k download

Solved: How to scan new LUNs in Redhat Linux

In this post we will discuss how to scan new LUNs allocated by storage team to a Redhat Linux system.
There are two ways of scanning the LUNs
Method 1:-
Find how many SCSI bus controllers you have

Go to directory /sys/class/scsi_host/ and list it’s contents.

cd /sys/class/scsi_host/

[root@scsi_host]# ls

host0 host1 host2

[root@scsi_host]#

Here we can see we have three SCSI bus controllers. So in below command replace hostX with these directory names.

Run the Command ,

echo "- - -" > /sys/class/scsi_host/hostX/scan

[root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host0/scan

[root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host1/scan

[root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host2/scan

[root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host3/scan

TIP:- Here the “- – -” denotes CxTxDx i.e. Channel(controller) , Target ID and Disk or LUN number. This is asked in Linux Admin Interviews also.

Repeat the above step for all three directories.

If you have FC HBA in the system you can follow the steps as below:-

First check number of FC controllers in your system

#ls /sys/class/fc_hosthost0 host1 host2

To scan FC LUNs execute commands as

echo "1" > /sys/class/fc_host/host0/issue_lip

echo "1" > /sys/class/fc_host/host1/issue_lip

echo "1" > /sys/class/fc_host/host2/issue_lip

Tip :- Here echo “1” operation performs a Loop Initialization Protocol (LIP) and then scans the interconnect and causes the SCSI layer to be updated to reflect the devices currently on the bus. A LIP is, essentially, a bus reset, and will cause device addition and removal. This procedure is necessary to configure a new SCSI target on a Fibre Channel interconnect. Bear in mind that issue_lip is an asynchronous operation.

Verify if the new disk is visible now

fdisk -l |egrep '^Disk' |egrep -v 'dm-'

Method 2 :-

Next method is to scan using SG3 utility. You can install it using

yum install sg3_utils

Once installed run the command

/usr/bin/rescan-scsi-bus.sh

Solved: How to add swap space in Redhat or Ubuntu Linux

In this post we will see how we can add a file as swap space in Linux. Same steps are to be followed for Redhat and Ubuntu Linux.
Type the following command to create 100MB swap file (1024 * 100MB = 102400 block size):

dd if=/dev/zero of=/swap1 bs=1024 count=102400

Secure swap file
Setup correct file permission for security reasons, enter:

# sudo chown root:root /swap1# sudo chmod 0600 /swap1

Set up a Linux swap area
Type the following command to set up a Linux swap area in a file:

# sudo mkswap /swap1

Activate /swap1 swap space :

# sudo swapon /swap1

Update /etc/fstab file to make it persistent across reboot.

vi /etc/fstab

Add the following line in file:

/swap1 swap swap defaults 0 0

To check if the swap file is added or not
Type the following swapon command:

#sudo swapon -sFilename Type Size Used Priority/dev/dm-0 partition 839676 0 -1/swap1 file 102396 0 -2

It should show you the new file.
If you want add a logical volume for swap please refer how to add LV for swap .

How to add logical volume for swap in Redhat Linux

In our last post we have seen how to add a file for swap space.
In this post we will see how to add a LVM2 Logical Volume as swap.
Here we have a VG name VG1 in which we will create a volume LV1 of 1GB.

# lvcreate VG1 -n LV1 -L 1G

Format the new swap space using mkswap:

# mkswap /dev/VG1/LV1

Update /etc/fstab file with below entry:

# /dev/VG1/LV1 swap swap defaults 0 0

Enable the extended logical volume:

# swapon -v /dev/VG1/LV1

Solved: How to change the keyboard layout for Redhat Linux

Nowadays we work as global teams and with people speaking different languages.
Some times you may face a situation where the Linux OS is installed with preference to another language e.g. French. The layout of french keyboard is different from that of US keyboard. Thus if you type “A” in US keyboard it will actually print “Q” . (Here you can get images of french keyboard)
This can be very frustrating since you are already accustomed with the US keyboard layout.
To get you out of this situation the easiest way is that once you login to the linux box. Run below command.

loadkeys us

This simple command will map the session with US keyboard layout. So now when you type “A” in your US layout keyboard it will be printed as “A” only. And this won’t change any langs in OS as it is mapped only to your session.
Do note that before you login you will still have to type userid and password in french layout only. Command can obviously be executed only after you login. So the image link i shared above should be helpful in getting you through the login stage.
Hope this post helps you.