Category: linux

In this post gonna explain what is migration, types and steps to be followed in migration.

What is Migration?

Migration is used to move the Data/Storage/Server/ from one to another (Server/Storage)

Pre-Requests:

1. Hardware must be the same or updated one in Destination.
2. Connectivity should be established between the source and destination.
3. Tools for Operating System related migrations.

Migration types:

1. DR Functionality
2. Forklift

III. MSP Oracle

1. Storage, Oracle (Storage/ggate)
2. V2V (LPAR), V2V (VM), V2V (VPAR), V2V (Clone VM)
3. P2V, P2V (VM), P2V (LPAR), P2V (NPAR) , P2P

VII. Seed-n-Swing (Physical), Seed-n-Swing (VM)

Steps involved in Migration:

1. Data gathering
2. Building a New server
3. Post Provisioning
4. Start Migration
5. Decommissioning

Data gathering:

As per my knowledge, I have some details which we need to check from the old server. Details are below Server Name,Building Name,Source DC,Target DC,Migration Method,Environment,Server Status in Tool,HW Server Vendor,Operating System,OS Version,Model of Server,NFS,No of Physical CPUs,No of Cores per CPU,Memory (GB),Number of Physical NICs in Use,NIC Teamed,Data NIC IP address,Data NIC subnet mask,Data NIC gateway,Data NIC MAC Address,Other NIC Ips,DNS Servers in order,Boot From SAN?,VG Name,Free space in VG,LV,No of LUNs,Total External Storage in GB,SAN type seen by Powerpath,Connected HBA WWN,Disconnected HBA WWN,Is HP DDMI Agent Running?,Last reboot – uptime,Forsee any issue in the mig method, based on SAN/Network,Lun counts,Storage type,Array_id,Total Size,Internal Disk size.

Building a New server:

We have to create a new server for migration based on Migration types and keep in mind the date which we gathered from old server. Example: No need of new server like Forklift migrations

Post provisioning:

Once the server build has completed, have to perform below post build tasks

Be compliance in DNS entries and hosts file entries (/etc/hosts), NTP Server Configured or not, Backup is done if it’s necessary, etc… Based on the Data gathering.

We have to vulnerability scan and fix the security patch errors (FAIL’s and WARNING’s) which will be present in the new servers.

Migration:

1. Create the file systems in new server based on old server with same VG, LV and PV name and size.
2. Copy the boot file system from source to Destination Server. Need to do manual copy from source to destination server in Linux Server’s like Red hat. Will use tools to take image in AIX, etc…
3. Have to do rsync the Data filesystem from source to Destination.
4. Move the LUN’s to the target server if it’s applicable.
5. Copy the applications from old to target server.
6. Set the IP Address, DNS and other stuffs based on the Data gathering.
7. Get the server in live once all these stuffs completed.

Decommissioning the old server:

1. Check what are all the jobs and applications running and get the help from concern team to stop the running applications.
2. Temporarily disable the backup, Mail, triggers, Disconnect the Database, Disable the NIC (Ethernet).
3. Wait for some days without shutting down the server to confirm whether we are getting any call back from any team for any issue in new server.
4. If we don’t hear any issues then will go ahead with disabling backup, mail, Triggers, Database, Network permanently.
5. And then will turn of the server the Server and will remove the server from Rack.

Thanks for choosing the blog. Comments are welcome…

Multipathing is used for Load Balancing, path failover & Recover for block devices in Linux.

Load balancing:

The workload is distributed across the available hardware components.

Path failover & Recover:

Will use redundant I/O channels to redirect the read and write operations when one or more paths no longer available.

Prerequisites RPM’s:

1. device-mapper-1.02.77-9.el6.x86_64
2. device-mapper-multipath-libs-0.4.9-64.0.1.el6.x86_64
3. device-mapper-multipath-0.4.9-64.0.1.el6.x86_64

Daemon: Multipathd

Configuration file: /etc/multipath.conf

The “multipath.conf” has five sections:

1. System level defaults
2. Blacklisted devices
3. Blacklist exceptions
4. Storage controller specific settings
5. Device specific settings

Simple steps to configure multipath:

1. For configuring the Multipath in Redhat Linux, device-mapper-multipath should be installed. You can verify It by using below command that it is installed or not:

#rpm -q device-mapper*

2. If it is not installed, install it by using below command.

#yum install device-mapper

3. After installation, start to configure multipath

#cd /etc

#mv multipath.conf multipath.conf.dist

#sed ‘/^#/d; /^$/d’ multipath.conf.dist > multipath.conf

#vi multipath.conf

Change to blacklist local hard drive only,

blacklist {
devnode “sda”
}

4. Now start the Multipath service

#Service Multipathd start
#chkconfig Multipathd on

5. Now Verify the disk paths

#fdisk -l
#sfdisk –s

Commands:

#service Multipathd start – to start the multipath service

#service Multipathd stop – to stop the multipath service

#service Multipathd reload – To update the modified configurations to replicate without restarting the service.

#multipath –ll – To list all the multipathed devices

#multipath –F – to stop the multipath

            First we make sure the firewall service is running before going to do any work related to ports.

Use the command to check the firewall service status:

[root@server ~]# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
 Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
 Active: active (running) since Sun 2017-10-29 08:46:09 IST; 4min 23s ago
 Docs: man:firewalld(1)
 Main PID: 523 (firewalld)
 CGroup: /system.slice/firewalld.service
 └─523 /usr/bin/python -Es /usr/sbin/firewalld --nofork --...

Oct 29 08:46:07 server systemd[1]: Starting firewalld - dynamic fir....
Oct 29 08:46:09 server systemd[1]: Started firewalld - dynamic fire....
Hint: Some lines were ellipsized, use -l to show in full.

Now we came to know that currently firewall is running and will check what are all the zone’s available and in public zone what are all the ports enabled/Listening, using below commands.

Command to check the available zone’s:

[root@server ~]# firewall-cmd --get-zones
work drop internal external trusted home dmz public block

Command to check the listening ports in public zone:

 [root@server ~]# firewall-cmd --zone=public --list-all
public (active)
 target: default
 icmp-block-inversion: no
 interfaces: enp0s8
 sources:
 services: dhcpv6-client mountd nfs rpc-bind ssh
 ports:
 protocols:
 masquerade: no
 forward-ports:
 sourceports:
 icmp-blocks:
 rich rules:

[root@server ~]# firewall-cmd --zone=public --add-port=8080/tcp --permanent
success

[root@server ~]# firewall-cmd --reload
success

[root@server ~]# firewall-cmd --zone=public --list-all
public (active)
 target: default
 icmp-block-inversion: no
 interfaces: enp0s8
 sources:
 services: dhcpv6-client mountd nfs rpc-bind ssh
 ports: 8080/tcp
 protocols:
 masquerade: no
 forward-ports:
 sourceports:
 icmp-blocks:
 rich rules:

[root@server ~]# firewall-cmd --zone=public --remove-port=8080/tcp --permanent
success
[root@server ~]# firewall-cmd --reload
success
[root@server ~]# firewall-cmd --zone=public --list-all
public (active)
 target: default
 icmp-block-inversion: no
 interfaces: enp0s8
 sources:
 services: dhcpv6-client mountd nfs rpc-bind ssh
 ports:
 protocols:
 masquerade: no
 forward-ports:
 sourceports:
 icmp-blocks:
 rich rules:

[root@server ~]# firewall-cmd --get-active-zone
external
 interfaces: enp0s3
public
 interfaces: enp0s8

[root@server ~]# firewall-cmd --get-zone-of-interface=enp0s3
external

[root@server ~]# firewall-cmd --permanent --zone=public --list-all
public
 target: default
 icmp-block-inversion: no
 interfaces:
 sources:
 services: dhcpv6-client mountd nfs rpc-bind ssh
 ports:
 protocols:
 masquerade: no
 forward-ports:
 sourceports:
 icmp-blocks:
 rich rules:

[root@server ~]# firewall-cmd --get-default-zone
public

[root@server ~]# firewall-cmd --set-default-zone=home
success