RMAN backup in NOARCHIVELOG Mode

Taking full database backup using RMAN when database is in NOARCHIVELOG Mode

When the database is running in NOARCHIVELOG mode then you can take only offline full database backups. i.e. you cannot take online backups.

To take full backup using RMAN when the database is in NOARCHIVELOG mode, the database should not be opened but it should be in the mounted state

To take offline full database backup using RMAN do the following

Step 1

Assuming the database is not started. Set the ORACLE_SID environment variable  to your database SID and start RMAN by typing the following command

$export ORACLE_SID=test
$rman target system/manager nocatalog

When you type the above command, RMAN will start with the following messages and you will get the RMAN prompt

Step 2

Start the instance and mount the database by typing the following command at RMAN prompt

RMAN> startup mount;

Step 3

To take full database backup type the following command

RMAN> backup full database tag 'myfullbackup';

The above the command will backup the full database and it will create the backupsets in the directory which is set in theDB_RECOVERY_FILE_DEST parameter. In our case the parameter is set to the following path "/u02/oracle/testdb/flash"

If you want to create the backupsets in other directory path then, you have to include the FORMAT option in the above command. For example the following command will create backupsets in the "/u02/oracle/mybackup" directory

 RMAN> backup full database format '/u02/oracle/mybackup/%U' tag 'myfullbackup'

The %U means RMAN should generate unique filenames for backupsets

Step 4

That's it the backup is over. We can start the database by typing the following

RMAN> alter database open;

If you want, you can view the back upsets by going into the following directory using O/s commands

Bonding in RHEL 6

NIC Bonding in RHEL6

 Solution

Red Hat Enterprise Linux allows administrators to bind multiple network interfaces together into a single channel using the bonding kernel module and a special network interface called a channel bonding interface. Channel bonding enables two or more network interfaces to act as one, simultaneously increasing the bandwidth and providing redundancy. The behavior of the bonded interfaces depends upon the mode, either hot standby or load balancing service.

           

Steps for configuring bonding

In this document we are configuring bond0 with interfaces eth0 and eth1

Step 1- Load Kernel module

For a channel bonding interface to be valid, the kernel module must be loaded. To ensure that the module is loaded when the channel bonding interface is brought up, create a new file as root named <bonding>.conf in the /etc/modprobe.d/ directory. Note that we can name this file anything but it should with ends with a .conf extension. Insert the following line in this new file alias bond<N> bonding

Replace <N> with the interface number, such as 0. If we want to configure  configuring more than on bonding interface, For  each configured channel bonding interface, there must be a corresponding entry in  /etc/modprobe.d/<bonding>.conf file

In this example we are configuring bond0 and  file name is bonding.conf

  [root@praji2 modprobe.d]# cat /etc/modprobe.d/bonding.conf

  alias bond0 bonding

Step2- create channel bonding interface

We  need to create a channel bonding interface configuration file on /etc/sysconfig/network-scripts/ directory called ifcfg-bond<N> , replacing <N> with the number for the interface, such as 0 and specify the bonding parameters on the file. Here we are creating ifcfg-bond0 file with following contents

[root@praji2 network-scripts]# cat ifcfg-bond0

DEVICE=bond0

IPADDR=172.16.1.207

NETMASK=255.255.255.0

ONBOOT=yes

BOOTPROTO=none

USERCTL=no

BONDING_OPTS="mode=0 miimon=1000"

Step 3- Configure Network interfaces

After the channel bonding interface is created, the network interfaces to be bound together must be configured by adding the MASTER= and SLAVE= directives to their configuration files. The configuration files for each of the channel-bonded interfaces can be nearly identical. For example, if two Ethernet interfaces are being channel bonded, both eth0 and eth1 may look like the following example

Interface eth0 configuration

 [root@praji2 network-scripts]# cat ifcfg-eth0

DEVICE=eth0

ONBOOT=yes

MASTER=bond0

SLAVE=yes

BOOTPROTO=none

USERCTL=no

TYPE=Ethernet

Interface eth1 configuration

[root@praji2 network-scripts]# cat ifcfg-eth1

DEVICE=eth1

ONBOOT=yes

MASTER=bond0

SLAVE=yes

BOOTPROTO=none

TYPE=Ethernet

USERCTL=no

After configuring the interfaces we have to bring up the bond by using command

[root@praji2 network-scripts]# ifconfig bond0 up

If the bonding is correctly configured we can view the configuration using ifconfig command

[root@praji2 network-scripts]# ifconfig

bond0     Link encap:Ethernet  HWaddr 00:0C:29:69:31:C4

          inet addr:172.16.1.207  Bcast:172.16.1.255  Mask:255.255.255.0

          inet6 addr: fe80::20c:29ff:fe69:31c4/64 Scope:Link

          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1

          RX packets:19676 errors:0 dropped:0 overruns:0 frame:0

          TX packets:342 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:1623240 (1.5 MiB)  TX bytes:42250 (41.2 KiB)

eth0      Link encap:Ethernet  HWaddr 00:0C:29:69:31:C4

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:10057 errors:0 dropped:0 overruns:0 frame:0

          TX packets:171 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:832257 (812.7 KiB)  TX bytes:22751 (22.2 KiB)

          Interrupt:19 Base address:0x2000

eth1      Link encap:Ethernet  HWaddr 00:0C:29:69:31:C4

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:9620 errors:0 dropped:0 overruns:0 frame:0

          TX packets:173 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:791043 (772.5 KiB)  TX bytes:20207 (19.7 KiB)

          Interrupt:19 Base address:0x2080

lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:2 errors:0 dropped:0 overruns:0 frame:0

          TX packets:2 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:104 (104.0 b)  TX bytes:104 (104.0 b)

To view all existing bonds we can run following command, it will list bond0

[root@praji2 network-scripts]# cat /sys/class/net/bonding_masters

bond0

To view the existing mode of bonding we can use following command

[root@praji2 network-scripts]# cat /sys/class/net/bond0/bonding/mode

balance-rr 0

For verifying bonding , we can use following command. It will list bonding details

[root@praji2 network-scripts]# cat /proc/net/bonding/bond0

Ethernet Channel Bonding Driver: v3.5.0 (November 4, 2008)

Bonding Mode: load balancing (round-robin)

MII Status: up

MII Polling Interval (ms): 1000

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: up

Link Failure Count: 0

Permanent HW addr: 00:0c:29:69:31:c4

Slave Interface: eth1

MII Status: up

Link Failure Count: 0

Permanent HW addr: 00:0c:29:69:31:ce

  

 bonding modes

Several policies are available in bonding, this mode can be set using directive mode=<value>

The <value> can be one of:

balance-rr or 0 — Sets a round-robin policy for fault tolerance and load balancing. Transmissions are received and sent out sequentially on each bonded slave interface beginning with the first one available.

active-backup or 1 — Sets an active-backup policy for fault tolerance. Transmissions are received and sent out via the first available bonded slave interface. Another bonded slave interface is only used if the active bonded slave interface fails.

balance-xor or 2 — Sets an XOR (exclusive-or) policy for fault tolerance and load balancing. Using this method, the interface matches up the incoming request's MAC address with the MAC address for one of the slave NICs. Once this link is established, transmissions are sent out sequentially beginning with the first available interface.

broadcast or 3 — Sets a broadcast policy for fault tolerance. All transmissions are sent on all slave interfaces.

802.3ad or 4 — Sets an IEEE 802.3ad dynamic link aggregation policy. Creates aggregation groups that share the same speed and duplex settings. Transmits and receives on all slaves in the active aggregator. Requires a switch that is 802.3ad compliant.

balance-tlb or 5 — Sets a Transmit Load Balancing (TLB) policy for fault tolerance and load balancing. The outgoing traffic is distributed according to the current load on each slave interface. Incoming traffic is received by the current slave. If the receiving slave fails, another slave takes over the MAC address of the failed slave.

balance-alb or 6 — Sets an Active Load Balancing (ALB) policy for fault tolerance and load balancing. Includes transmit and receive load balancing for IPV4 traffic. Receive load balancing is achieved through ARP

Linux Rename Eth0 Network Interface Card Name

Linux Rename Eth0 Network Interface Card Name

Step #1: Find out the MAC address of the Ethernet device

Type the following command:
# ifconfig -a | grep -i --color hwaddr

 Sample outputs:

eth0      Link encap:Ethernet  HWaddr b8:ac:6f:65:31:e5
pan0      Link encap:Ethernet  HWaddr 4a:71:40:ed:5d:99
vmnet1    Link encap:Ethernet  HWaddr 00:50:56:c0:00:01
vmnet8    Link encap:Ethernet  HWaddr 00:50:56:c0:00:08
wlan0     Link encap:Ethernet  HWaddr 00:21:6a:ca:9b:10

Note down the MAC address.

Step #2: Rename eth0 as wan0

To rename eth0 as wan0, edit a file called 70-persistent-net.rules in /etc/udev/rules.d/ directory, enter:

 # vi /etc/udev/rules.d/70-persistent-net.rules
The names of the Ethernet devices are listed in this file as follows:

# PCI device 0x14e4:0x1680 (tg3) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="b8:ac:6f:65:31:e5", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

Locate and identify the line with the NIC from step 1 (look for the MAC address). It may look like above. In this example, the interface eth0 will be renamed to wan0 (change NAME="eth0" to NAME="wan0"):

# PCI device 0x14e4:0x1680 (tg3) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="b8:ac:6f:65:31:e5", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="wan0"

Save and close the file. Reboot the system to test changes:

 # reboot
Verify new settings:
# ifconfig -a
# ifconfig wan0
# ifconfig -a | less
# ip addr show



Oracle Data Guard Interview Questions

Oracle Data Guard Interview Questions

1. How to setup Data Guard?

2. What are different types of modes in Data Guard and which is default?
Maximum performance:
This is the default protection mode. It provides the highest level of data protection that is possible without affecting the performance of a primary database. This is accomplished by allowing transactions to commit as soon as all redo data generated by those transactions has been written to the online log.

Maximum protection:
This protection mode ensures that no data loss will occur if the primary database fails. To provide this level of protection, the redo data needed to recover a transaction must be written to both the online redo log and to at least one standby database before the transaction commits. To ensure that data loss cannot occur, the primary database will shut down, rather than continue processing transactions.

Maximum availability:
This protection mode provides the highest level of data protection that is possible without compromising the availability of a primary database. Transactions do not commit until all redo data needed to recover those transactions has been written to the online redo log and to at least one standby database.

3. How many standby databases we can create (in 10g/11g)?
Till Oracle 10g, 9 standby databases are supported.
From Oracle 11g R2, we can create 30 standby databases.

4. What are the parameters we have to set in primary/standby for Data Guard?

5. What is the use of fal_server and fal_client, is it mandatory to set these?

6. What are differences between physical, logical, snapshot standby and ADG (or) what are different types of standby databases?
Physical standby – in mount state, MRP will apply archives
ADG (Active Data Guard) – in READ ONLY state, MRP will apply archives
Logical standby – in READ ONLY state, LSP will run
Snapshot standby databases – Physical standby database can be converted to snapshot standby database, which will be in READ WRITE mode, can do any kind of testing, then we can convert back snapshot standby database to physical standby database and start MRP which will apply all pending archives.

7. How to find out backlog of standby?
select round((sysdate - a.NEXT_TIME)*24*60) as "Backlog",m.SEQUENCE#-1 "Seq Applied",m.process, m.status 
from v$archived_log a, (select process,SEQUENCE#, status from v$managed_standby where process like '%MRP%')m where a.SEQUENCE#=(m.SEQUENCE#-1);

8. If you didn't have access to the standby database and you want to find out what error has occurred in a Data Guard configuration, what view would you check in the primary database to check the error message?
You can check the v$dataguard_status view. 
select message from v$dataguard_status;

9. How can you recover standby which far behind from primary (or) without archive logs how can we make standby sync?
By using RMAN incremental backup.

10. What is snapshot standby (or) How can we give a physical standby to user in READ WRITE mode and let him do updates and revert back to standby?
Till Oralce 10g, create guaranteed restore point, open in read write, let user do DMLs on snapshot standby, flashback to restore point, start MRP.
From Oracle 11g, convert physical standby to snapshot standby, let user do DMLs on snapshot standby, convert to physical standby, start MRP.

11. What are new features in 11g Data Guard?

12. What are the uses of standby redo log files?
A standby redo log resides on the standby database site. The standby redo log file is similar to an online redo log, except that a standby redo log is used to store redo data that has been received from a another/primary database.

13. What is dg_config?

14. What is RTA (real time apply) mode MRP?

15. What is the difference between normal MRP (managed apply) and RTA MRP (real time apply)?

16. What are various parameters in log_archive_dest and it’s use?

17. What is the difference between SYNC/ASYNC, LGWR/ARCH, and AFFIRM/NOAFFIRM?

18. What is Data Guard broker (or) what is the use of dgmgrl?

19. What is StaticConnectIdentifier property used for?

20. What is failover/switchover (or) what is the difference between failover and switchover?
Switchover – This is done when both primary and standby databases are available. It is pre-planned.

Failover – This is done when the primary database is NO longer available (i.e. in a Disaster). It is not pre-planned.

21. What are the background processes involved in Data Guard?
RFS, MRP, LSP

RMAN Interview Questions for DBAs

RMAN Interview Questions for DBAs

1. Difference between catalog and nocatalog?
Recovery catalog is central and can have information of many databases.

2. Difference between using recovery catalog and control file?
When new incarnation happens, the old backup information in control file will be lost. It will be preserved in recovery catalog.
In recovery catalog, we can store scripts.
Recovery catalog is central and can have information of many databases.

3. Can we use same target database as catalog?
No. The recovery catalog should not reside in the target database (database to be backed up), because the database can't be recovered in the mounted state.

4. How do u know how much RMAN task has been completed?
By querying v$rman_status or v$session_longops

5. From where list and report commands will get input?
Both the commands command quering v$ and recovery catalog (RC) views. V$BACKUP_FILES or many of the recovery catalog views such as RC_DATAFILE_COPY or RC_ARCHIVED_LOG.

6. Command to delete archive logs older than 7days?
RMAN> delete archivelog all completed before sysdate-7;

7. By default how many days backup RMAN stores?

8. What is the use of crosscheck command in RMAN?
Crosscheck will be useful to check whether the catalog information is intact with OS level information.

9. What are the differences between crosscheck and validate commands?
Validate command is to examine a backup set and report whether it can be restored. RMAN scans all of the backup pieces in the specified backup sets and looks at the checksum to verify that the contents are intact so that backup can be successfully restored if necessary.

Crosscheck command is to verify the status of backups and copies recorded in the RMAN repository against media such as disk or tape. The crosscheck command only processes files created on the same device type as the channel running crosscheck.

10. Which is one is good, differential (incremental) backup or cumulative (incremental) backup?
A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

11. What is Level 0, Level 1 backup?
A level 0 incremental backup, which is the base for subsequent incremental backups, copies all blocks containing data, backing the datafile up into a backup set just as a full backup would. A level 1 incremental backup can be either of the following types:
A differential backup, which backs up all blocks changed after the most recent incremental backup at level 1 or 0
A cumulative backup, which backs up all blocks changed after the most recent incremental backup at level 0

12. Can we perform level 1 backup without level 0 backup?
If no level 0 backup is available, then the behavior depends upon the compatibility mode setting. If compatibility < 10.0.0, RMAN generates a level 0 backup of the file contents at the time of the backup. If compatibility is >= 10.0.0, RMAN copies all blocks changed since the file was created, and stores the results as a level 1 backup. In other words, the SCN at the time the incremental backup is taken is the file creation SCN.

13.  Will RMAN put the database/tablespace/datafile in backup mode?
Nope.

14. What is snapshot control file?
The snapshot control file is a copy of a database control file created in an operating system-specific location by RMAN. RMAN creates the snapshot control file so that it has a consistent version of a control file to use when either resynchronizing the recovery catalog or backing up the control file.

15. What is the difference between backup set and backup piece?
Backup set is logical and backup piece is physical.

16. RMAN command to backup for creating standby database?
RMAN> duplicate target database to standby database ....

17. How to do cloning by using RMAN?
RMAN> duplicate target database …

18. Suppose you lost one datafile and DB is running in ARCHIVELOG mode. You have full database backup of 1 week/day old and don’t have backup of this (newly created) datafile. How do you restore/recover file?
create the datafile and recover that datafile.
SQL> alter database create datafile ‘…path..’ size n;
RMAN> recover datafile file_id;

19. What is obsolete backup and expired backup?
A status of "expired" means that the backup piece or backup set is not found in the backup destination.
A status of "obsolete" means the backup piece is still available, but it is no longer needed. The backup piece is no longer needed since RMAN has been configured to no longer need this piece after so many days have elapsed, or so many backups have been performed.

20. What is the difference between hot backup and RMAN backup?
For hot backup, we have to put database in begin backup mode, then take backup.
RMAN won’t put database in backup mode.

21. How to put manual/user-managed backup in RMAN (recovery catalog)?
By using catalog command.
RMAN> CATALOG START WITH '/tmp/backup.ctl';

22. What are new features in Oracle 11g RMAN?

23. What is the difference between auxiliary channel and maintenance channel?

24. What are new features in Oracle 12c RMAN?

25. What is the use of nofilenamecheck in rman
When NOFILENAMECHECK is used with the DUPLICATE command, RMAN does not validate the filenames during restoration. If the primary database and the standby database are on the same host, The DUPLICATE NOFILENAMECHECK option should not be used.

26. Do we need to shutdown db to change block change tracking file?
No need