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Data Recovery And Protection in Teradata

Screenshot_36

Locks:- Prevent simultaneous access an the objects

RAID:- Prevent from disk failure

Fall back:- Prevent from Amp failure

Journal:- Prevent from Image failure

CLIQUE:- Prevent from Node failure

 

ARC[Archive and Recovery]

A Means of Archiving data to tape and disk and restoring data to teradata database backup application software includes the following

Teradata archive and recovery, Net Valet, Net Backup,Tivoli Storage Manager,  Teradata Extension.

Note:- the above all feature are provides teradata, to makes teradata as highly

Screenshot_37

LOCK Held

Table Name

“A” having Lock

Access

Read

Write

Exclusive

Access

 √ √ √ √

X

Read

 √ √ √

    X

X

Write

 √ √

     X

    X

X

Exclusive

 √

      X

     X

    X

X

 

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Access

DATA In consistent, select

Read

DATA consistent, select

Write

Insert, update, Delete

Exclusive

DDL Statement

HUT LOCK

  •  This is the lock applied while we are doing archive and recovery.

Screenshot_38

Syntax- Locking row for

<Lock type><Sql Queue >

Example

Locking row for access SEL* From party Locking row for write SEL*from party

Syntax Table level

Locking table<Table name> for

<Lock type>

Example Locking table party for access

Release Lock

Syn Release Lock data base name Table name:

Advantages of Access Lock

a) Permit queue access to a table multiuser Environment

b) Having minimal blocking efforts on other quereries

c) Very use full for aggregating huge number of rows.

Screenshot_39

2Access Lock applied Immediately even through there are many locking it’s that query

Note- Refer to the complete description And practical page NO:50 to 52 new material

RAID-[REDUNDENT ARRAY OF IN DEPENDENT DISK DRIVE] Refer to the page No: 53 To 54 for the description

Screenshot_40

RAIDO,RAID1,RAID2,——RAID5,RAIDS,RAIDE etc.,

Teradata supports

RAID1, RAID5, RAIDS

RAID1:[MIRRORING TECHNIQUE] Real time use

Advantage:-quick Availability, primary disk failure, recovers a/s easier

Screenshot_41

Draw back

  1. 50% Memory wastage
  2. Operations double[Insert, update, Delete] 

RAID5:-[PARTY CHECKING TECHNIQUE]

Screenshot_42

P= B1+B2+B3

B1=P- B2-B3

Advantage 25% only memory addition[less memory]

Draw back: Recovery slow

Fall back:– Refer to the page no:54

Usage: At the time AMP failure, it permits to access rows in others AMP’S

Party:            PID  PNM

1                               X

2                              Y

3                              Z

4                             M

Screenshot_43

Advantage High availability or fast data[At time of failure, immediate redirection to fall back AMP, so that data highly accessible]

Draw back

  1. 50% Space waste
  2. Operations double

Note In real time we use raid1 and fall back as part data protection and recovery general we back cluster environment in real time

Fall back Cluster(3,4,8,16)

Usage Cluster is nothing but group of Amp’s, then it is take single place, where fall back maintain with in the same group

It is advantage because, we will skip scanning other Amp’s And other groups

Note If 2 Amp’s went down RDBMS halted, Tera data recommend 4 Amp’s for the cluster for detail description refer to page No:55 To get average performance

Journal  Journal is a kind of record, which close some kind of activity

No. of Amp(N)Work load1+1/N-1Remains should available
161.0615
810127
41.33
221

Journal Types

Recovery journal

Transient Journal

Pernanenet journal

Single image 2 one copy of data

Dual image 2 two copies of the data

Before image2 before change

After image 2 after change taking the image

Recovery Journal

  1. Automatic[of fall back is there]

Screenshot_44

Usage Once the down Amp came online[repaired] to recovery successfully, recovery journal log are useful

Check out the top Teradata Interview Questions now!

2.Transcient journal [it helps is to do successful]

Transaction nothing but logical collection of statement, which can be either failure or successful

Here transaction journal helps of to do successful roll back in case of transaction failed.

Successful Transaction                                    Failed Transaction

BEGIN Transaction;//;Transient             _________________  journal activated(T.J)

  1. S) INSERT PARTY;//Back up image ____________ B.I (B.I)taken
  1. S) UPDATE PARTY; ________(party)
  2. S) Delete Party; ________(failed)

END TRANSACTION;

1.Drops B.I                 B.I dropped               1.Roll back happens

2.Discards T.J            T.J discarded             2.B.I reaplied

NoteTransient journal uses before image for it operations

 

3.Permanent journal

  1. It help us to doing fall(or)partial selective recovery
  2. It uses both before and after image[single and clual]

Ex: Till yesterday the data was corrupted

Till yesterday  2B.I

Mon                             à A.I

|

|

|

Sun 2A.I

Full recovery= B.I+[Mon-Sun] A.I

Selection recovery = B.I+[Mon-This] A.I

Note:- Refer to the material description of example the material

Check Sum

  1. It used prevent for disk input, output Errors
  2. Check sum is completed value, from in algorithm gerierate by an algorithm on the data block this Algorithm applied storage and retrieval level it these are no difference, there a no disk input, output error

Screenshot_45

If x=y No, disk input, output error

If x<>y, disk input, output error

Default:- Algorithm applied on data block recording value specified DBC Control utility according to table type

Note:– Many people they using in real time for implement Change data capturing concepts

Clique:-

  • Group of nodes sharing common disk array Driver is called clique
  • Each and every multi system have at least one clique
  • The nodes of clique connected to the controls of disk array
  • Each clique has same no of nodes

Advantages:-

  • It provides data availability, even the nodes failed by Migrating virtual processor[PE, AMP]
  • Migrating from fail node other node[operation node]

Note:-

  1. Multiple clique in the same system must have same no. of nodes
  2. All this nodes are communicate each other by using by NET

HSN[HOT STAND BY NODE]

It is node, that is number of clique that is not configure that execute any tera data vproc, if a node in the clique fail

The Amps from the fail node move to the thigh HSN Stand  by Node in this way it decrease performance in Zero space zero percentage

For Indepth knowledge on Teradata click on:

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Data Recovery And Protection in Teradata
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