disaster recovery1

8/3/2019 Disaster Recovery1

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Rishin Krishnan

Santosh Ramamorthy

Abin Jose

Gijo George

Akhil Shasidharan

DISASTER RECOVERY &

ACCESS CONTROL SYSTEM


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DISASTER RECOVERY

Disaster recovery is a process that you can use to help recover information systems and

data, if a disaster occurs.

Disaster recovery planning is the work that is devoted to preparing all the actions that

must occur in response to a disaster.

The planning includes the selection of a strategy to help recover valuable data

The selection of the appropriate disaster recovery strategy depends on your business

requirements.


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FAILOVER CLUSTERING

Microsoft SQL Server 2000 failover clustering is designed to failover automatically if a

hardware failure or a software failure occurs.

SQL Server 2000 failover clustering is used to create a failover cluster for a single

instance of SQL Server 2000 or for multiple instances of SQL Server 2000.

Failover clustering allows a database system to automatically switch the processing of

an instance of SQL Server from a failed server to a working server

Failover clustering is helpful if an operating system failure occurs or if you perform a

planned upgrade of the database system resources


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DISADVANTAGES

failover clustering is designed for high server availability with almost no server

downtime, the clustered nodes should be geographically close to each other.

failover clustering is designed for high server availability with almost no server

downtime, the clustered nodes should be geographically close to each other.

The maintenance of two servers is two times the cost of maintaining a single server.


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PEER-TO-PEER TRANSACTIONAL REPLICATION

Peer-to-peer transactional replication is designed for applications that might read or

might modify the data in any database that participates in replication.

Additionally, if any servers that host the databases are unavailable, you can modify the

application to route traffic to the remaining servers.

Read performance is improved because you can spread activity across all nodes


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DISADVANTAGES

Peer-to-peer replication is available only in SQL Server 2005 Enterprise Edition.

All participating databases must contain identical schemas and data

You must have a publication enabled for peer-to-peer replication before you create

any subscriptions.

You must initialize subscriptions by using a backup or by setting the value of the

subscription synchronization type to replication supportonly.

Peer-to-peer transactional replication does not provide conflict detection or conflict

resolution.


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DATABASE MIRRORING

Database mirroring is a primarily software solution for increasing database

availability.

Database mirroring works with any supported database compatibility level.

Database mirroring increases data protection.

Database mirroring increases availability of a database.

Database mirroring improves the availability of the production database during

upgrades.


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DISADVANTAGES

The mirror database should be identical to the principal database. For example, all

objects, logins, and permissions should be identical.

Database mirroring involves the transfer of information from one computer to another

computer over a network. Therefore, the security of the information that SQL Server

transfers is very important.


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A WARM STAND BY SERVER

A standby server is useful to help recover data if a

disaster occurs. Two methods:-

Log shipping

Transactional replication


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LOG SHIPPING.. Log shipping is included in the resource kit for Microsoft SQL Server 7.0, and it is

fully incorporated in the Microsoft SQL Server 2000 Enterprise Edition and in the

Microsoft SQL Server 2000 Developer Edition.

Log shipping uses a standby server that is not used during regular operations.

When a standby server is restoring transaction logs, the database is in exclusivemode and it is unusable.


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STANDBY SERVER

A standby server is restoring transaction logs, the database is in exclusive mode and

it is unusable.

A standby server is useful to help recover data if a disaster occurs.

You can run batch reporting jobs between transaction log restorations or Database

Console Commands (DBCC) checks to continuously verify the integrity of the

standby server.


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DISADVANTAGES

The database is unusable during the restoration process because the database is in

exclusive mode on the standby server.

There is a lack of granularity. During the restoration process, all the changes in the

primary server are applied at the standby server. You cannot use log shipping to apply

changes to a few tables and to reject the remaining changes.

There is no automatic failover of applications. When the primary server fails because of

a disaster, the standby server does not failover automatically. Therefore, you must

explicitly redirect the applications that connect to the primary server to the standby

(failover) server.


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TRANSACTIONAL REPLICATION

Transactional replication replicates the data on one server (the publisher) to another

server (the subscriber) with less latency than log shipping.

You can implement transactional replication at the database object level such as the

table level.

You can use a push subscription to enforce transactional replication between two

servers with the primary server as the publisher and the standby server as the

subscriber


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DISADVANTAGES.

Schema changes or security changes that are performed at the publisher after

establishing replication will not be available at the subscriber.

The distributor in transactional replication uses an Open Database Connectivity

(ODBC) connection or an OLE Database (OLEDB) connection to distribute data.

However, log shipping uses the RESTORE TRANSACTION low-level Transact-SQL

statement to distribute the transaction logs. A RESTORE TRANSACTION statement

is much faster than an ODBC connection or an OLEDB connection.


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BACKUP AND RESTORE FEATURE

The Backup and Restore feature of SQL Server provides an important safeguard to

help protect critical data that you store in SQL Server databases.

You can create a copy of a database (a backup copy) by using the Backup and

Restore feature, and then store the copy of the database in a location that is

protected from the potential failure of the server that runs the instance of SQL

Server.


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DISK REDUNDANCY OF DATA BY USING A REDUNDANT

ARRAY OF INDEPENDENT DISKS

(RAID)

A RAID stores redundant data on multiple disks to provide greater reliability and less

downtime for servers.

RAID levels 0, 1, and 5 are generally used as recovery options for SQL Server. The

RAID technologies that are mentioned allow for the failure and the consequent

replacement of a single disk without the server going offline.


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They range from the simple password protection (Microsoft Access) to the complex

user/role structure supported by advanced relational databases(Oracle and Microsoft

SQL Server).

Its recommended individual database user accounts for each person who will be

accessing your database.

Server-based databases all support a user concept similar to that used in computer

operating systems.

It's technically possible to share accounts between users or simply use one user

account for each type of user that needs to access your database


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LIMITATIONS OF SHARING A/CS

First, it will eliminate individual accountability -- if a user makes a change to your

database (let's say by giving himself a $5,000 raise), you won't be able to trace it

back to a specific person through the use of audit logs.

Furthermore, if a specific user leaves your organization and you wish to remove his

or her access from the database, you'll be forced to change the password that all

users rely upon.


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METHODS FOR CREATING DATABASE.

The methods for creating user accounts vary from platform to platform (consult DBMS-

specific documentation for the exact procedure).

Microsoft SQL Server users should investigate the use of the sp_adduser stored

procedure.

Oracle database administrators will find the CREATE USER command useful.

For example, Microsoft SQL Server supports the use of Windows NT Integrated

Security.

If in an environment with a small number of users, you'll probably find that creating user

accounts and assigning permissions directly to them is sufficient for your needs.


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User accounts are assigned to role(s) and permissions are then assigned to the role as

a whole rather than the individual user accounts.

For example, we could create a DBA role and then add the user accounts of our

administrative staff to this role.

Thirdly, assign a specific permission to all present (and future) administrators by simply

assigning the permission to the role.

The procedures for creating roles varies from platform to platform.

MS SQL Server administrators should investigate the sp_addrole stored procedure

while Oracle DBAs should use the CREATE ROLE syntax.


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After defining users and roles, it's time to begin assigning permissions.

Populating database with users and roles next is to begin assigning permission

Its through the use of the SQL GRANT statement :- GRANT

[ON ]

TO

[WITH GRANT OPTION]


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SYNTAX

GRANT , allows us to specify the specific table permissions we are

granting

These can be either table-level permissions (such as SELECT, INSERT,

UPDATE and DELETE) or database permissions (such as CREATE TABLE,

ALTER DATABASE and GRANT)

More than one permission can be granted in a single GRANT statement.

Table-level permissions and database-level permissions may not be combined ina single statement.


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ON , is used to specify the affected table for table-level permissions.

This line is omitted if we are granting database-level permissions.

The third line specifies the user or role that is being granted permissions.

Finally, the fourth line, WITH GRANT OPTION, is optional

If this line is included in the statement, the user affected is also permitted to grant

these same permissions to other users.


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