Backup & Restore Part I

8/13/2019 Backup & Restore Part I

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Backup & Restore

Part I

Backup


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Backup

Backs up data while being changed

Dos not acquire locks and ignores existing locks

Backs up changes made to the database wile being backed up

- Performs a checkpoint and records the LSN of the oldest activetransaction

- Backs up data pages directly as is

- Backs up transactions since the LSN recorded (including opentransactions)

Degrades performance by only 5%10%


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Syntax

BACKUP DATABASE {database_name| @database_name_var}TO [,...n][WITH

[BLOCKSIZE = {blocksize| @blocksize_variable}]

[[,] DESCRIPTION = {text | @text_variable}][[,] DIFFERENTIAL][[,] EXPIREDATE = {date | @date_var}

| RETAINDAYS = {days| @days_var}][[,] FORMAT | NOFORMAT][[,] {INIT | NOINIT}][[,] MEDIADESCRIPTION = {text | @text_variable}][[,] MEDIANAME = {media_name | @media_name_variable}][[,] [NAME = {backup_set_name| @backup_set_name_var}][[,] {NOSKIP | SKIP}][[,] {NOUNLOAD | UNLOAD}][[,] [RESTART][[,] STATS [= percentage]]

]


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Permissions

BACKUP DATABASE and BACKUP LOG

permissions default to members of the

sysadminfixed server role, db_owner

fixed database role, who can transfer

permissions to other users, and to members

of the db_backupoperatorfixed databaserole.


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Backup media

Disk file (including network location)

- For a network location, make sure the serviceMSSQLServer loads with a domain user, and that that userhas sufficient NTFS permissions

Local tape device

- Can mix SQL Server backups and NT backups

Pipe (for self developed / 3rdparty backup software)


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Named dump devices

Named dump devices

- Logical name maps to a disk or a tape device

- If physical location changes, need to drop and recreate the device, but

all automated jobs do not need to be changed

sp_addumpdevice[@devtype =]

disk | pipe | tape,[@logicalname =]'logical_name',

[@physicalname =] 'physical_name'

Permissions:

Execute permissions default to members of the diskadminfixed serverrole.


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Examples

USE master

EXEC sp_addumpdevice 'disk','mydiskdump','c:\dump\dump1.bak

USE master

EXEC sp_addumpdevice 'disk','\\servername\sharename\path\filename.ext'

USE master

EXEC sp_addumpdevice 'tape',

'tapedump1', \\.\tape0


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From Enterprise Manager


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Supplying the direct location of

the backup device

- Has the same abilities as the named dump

device

- If the physical location of the device

changes, need to change it in all automated

jobs.


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Media set

Create a media set by specifying more thanone device in the backup statement.

All devices must be of the same type (DISK| TAPE | PIPE)

Cannot use a device that is part of a media

set alone, unless you specify the FORMAToption. In this case, backups from theoriginal media set can not be restored.


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Fu l l backup

Is required for following differential or transactionlog backups

Is current to the time the backup is finished

Examples:

BACKUP DATABASE db1 TO DISK =

\\servername\sharename\devname.bak

BACKUP DATABASE db1 TOmydiskdump WITH INIT

BACKUP DATABASE db1 TOmydiskdump WITH NOINIT


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Differential backup

Requires a preceding full backup

Backs up changed pages since the last full backup

When restoring, the full backup and the last

differential backup is needed

If a row was modified several times, backs up the

current image of the row Specify the option WITH DIFFERENTIAL in the

BACKUP statement


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Example

-- Create a full database backup first.

BACKUP DATABASE MyNwind

TO MyNwind_1

WITH INITGO

-- Time elapses.

-- Create a differential database backup,appending the backup

-- to the backup device containing the databasebackup.

BACKUP DATABASE MyNwind

TO MyNwind_1

WITH DIFFERENTIAL

GO


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Transaction log backup

Requires a preceding full backup (and

optionally a differential backup)

Backs up committed and uncommitted

transactions from the Transaction Log

Truncates the inactive part of the

transaction log* (until the oldest open

transaction)


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Syntax

BACKUP LOG {database_name| @database_name_var} {

[WITH{ NO_LOG | TRUNCATE_ONLY }]

}|{

TO [,...n][WITH

[BLOCKSIZE = {blocksize| @blocksize_variable}][[,] DESCRIPTION = {text | @text_variable}][[,] EXPIREDATE ={date | @date_var}

| RETAINDAYS ={days| @days_var}][[,] FORMAT | NOFORMAT][[,] {INIT | NOINIT}]

[[,] MEDIADESCRIPTION = {text | @text_variable}][[,] MEDIANAME = {media_name | @media_name_variable}][[,] [NAME ={backup_set_name| @backup_set_name_var}][[,] NO_TRUNCATE][[,] {NOSKIP | SKIP}][[,] {NOUNLOAD | UNLOAD}][[,] [RESTART]

[[,] STATS [=percentage]] ] }


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Example

-- Create the log backup device.

USE master

EXEC sp_addumpdevice 'disk', 'MyNwindLog1',

'c:\mssql7\backup\MyNwindLog1.dat'

-- Update activity has occurred before thispoint.

-- Back up the log of the MyNwind database.BACKUP LOG MyNwind

TO MyNwindLog1


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Acknowledgements:

Most of the info for the following topics were taken from the

book Inside SQL Server 7.0by Kalen Delaney


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Log truncate mode

When a database is in log truncate mode it is automatically

truncated when a checkpoint occurs.

In log truncate mode a checkpoint occurs in the followingcircumstances:

The log becomes 70 percent full.

The number of log records reaches the number SQL Server

estimates it can process during the time specified in the recovery

intervaloption.


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Log truncate mode

A database will be in log truncate mode in the following

situations:

- The database option trunc. log on chkpt. Is set to true- The database was never fully backed up

- A non logged operation was performed against the

database and it was never fully backed up since

- The Transaction Log was manually truncated using theBACKUP LOG WITH NO_LOG | TRUNCATE_ONLY

(in SQL Server 7.0 these are synonyms)


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Shrinking the transaction log

The Transaction Log is built internally from Virtual log files.

Transactions are written serially to the Transaction Log File.

The active portion of the transaction log begins from the oldestopen transaction until the last transaction.

Virtual log files are marked as reusable if they contain inactive

log records and were backed up.

The Transaction Log File can be truncated: Only in full virtual log files.

Only from the end.

Only if they are inactive and are marked as reusable.


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Shrinking the transaction log

This may lead to situations where the Transaction Log can not be truncated. Toovercome this, use the following procedure:

1. Backup or truncate the log to make sure earlier Virtual Log Files are reusable2. Execute dummy transactions (in a loop) so that the active VLF will move to an

earlier location.

3. Execute DBCC SHRINKDATABASE or DBCC SHRINKFILE to mark ashrinkpoint.

4. Repeat step 1 again to force the physical shrinkage.

* Tip: Use the DBCC LOGINFO(dbname) to see a list of the virtual log files.Those with status 2 are active. Continue with the dummy transactions until theactive VLF is at the beginning.


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BACKUP LOG WITH NO_TRUNCATE

This option was provided to enable backing up the Transaction Log in case the

disk containing the data files is damaged but the Transaction Log is still

intact.

Currently this option is available only if the .mdf file is still available.

To prepare for such a senario:

1. Place the PRIMARY FILEGROUP and the Transaction Log on the same

physical disk.

2. Create an additional filegroup:

ALTER DATABASE databaseADD FILEGROUPfilegroup_name

3. Mark the new filegroup as default:

ALTER DATABASE databaseMODIFY FILEGROUPfilegroup_nameDEFAULT


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Files and File Groups backup

Use with Very Large Databases were the backup

window is not sufficient for a full backup

If an index is created on a filegroup, all thefilegreoup or all the files belonging to that

filegroup are need to be backed up as a unit

If a table was created on one filegroup and its

indexes were created on separate filegroups, all

the filegroups involved need to be backed up as a

unit.


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Syntax

BACKUP DATABASE {database_name|

@database_name_var}

[,...n]

TO [,...n]

[WITH


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Examples

-- Back up the MyNwind file(s) and

filegroup(s)

BACKUP DATABASE MyNwindFILE = 'MyNwind_data_1',

FILEGROUP = 'new_customers',

FILE = 'MyNwind_data_2',

FILEGROUP = 'first_qtr_sales'

TO MyNwind_1

GO


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sp_detach_db & copy

sp_detach_db[@dbname=] 'dbname'[,[@skipchecks=] 'skipchecks']

Detach a database from the server and, optionally,run UPDATE STATISTICS on all tables beforedetaching (use the false option if you are moving /

copying the database to a read only media). Copy | move the files to the target location

Run sp_attach_db or sp_attach_single_file_db onthe target server


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Backup Options


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Backup Options

NAMEbackup name

DESCRIPTIONbackup description

INIT, NOINIToverwrite | append (if NOSKIP is specified, performs

safety checks)

SKIP, NOSKIPwhether to perform a safety check

FORMAT | NOFORMATwhether to rewrite the backup device and

ignore existing backup sets and not perform any safety checks

MEDIADESCRIPTION

MEDIANAMEif supplied, performs a media set name check


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Backup Options

EXPIREDATE | RETAINDAYSchecked if NOSKIP is performed

RESTARTrestarts the backup operation at the point it was

interrupted

This option can only be used for backups directed to tape media andfor backups that span multiple tape volumes. A restart operation never

occurs on the first volume of the backup.

NOUNLOAD | UNLOAD

STATS = n - Informs the percentage of the backup operation every n

percent of the backup

BLOCKSIZEfor media that requires a special block size


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Database Maintenance Plans


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Date post:	04-Jun-2018
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Backup & Restore Part I

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