Checkpointing is used to improve database recovery time. It periodically writes uncommitted transaction logs and dirty database pages to stable storage. This allows transactions committed before the last checkpoint to be ignored during recovery. Recovery involves undoing uncommitted transactions and redoing committed ones since the last checkpoint using the write-ahead logging protocol to ensure crash consistency. Shadow paging is an alternative technique that maintains a shadow page table to recover the pre-transaction state if needed. Automated backups and mirroring can further improve availability.
Power point presentation on backup and recovery.
A good presentation cover all topics.
For any other type of ppt's or pdf's to be created on demand contact -dhawalm8@gmail.com
mob. no-7023419969
Power point presentation on backup and recovery.
A good presentation cover all topics.
For any other type of ppt's or pdf's to be created on demand contact -dhawalm8@gmail.com
mob. no-7023419969
A closer quick understanding of different backup technologies and pros and cons backup & recovery,ntbackup,types of backups, windows backup path so far, differential backup, incremental backup, full backup, mirror backup. If you have have anyqueries please contact me at jabvtl@gmail.com
Recovery Techniques and Need of RecoveryPooja Dixit
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Recovery Techniques and Need of Recovery, 3 states of database Recovery:, DBMS Failure , Transaction FailureâŚ, System CrashâŚ, Disk FailureâŚ,LOG BASED , CONCURRENT TRANSACTION, CheckpointâŚ
A closer quick understanding of different backup technologies and pros and cons backup & recovery,ntbackup,types of backups, windows backup path so far, differential backup, incremental backup, full backup, mirror backup. If you have have anyqueries please contact me at jabvtl@gmail.com
Recovery Techniques and Need of RecoveryPooja Dixit
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Recovery Techniques and Need of Recovery, 3 states of database Recovery:, DBMS Failure , Transaction FailureâŚ, System CrashâŚ, Disk FailureâŚ,LOG BASED , CONCURRENT TRANSACTION, CheckpointâŚ
Take Care of Your Computer Part 2 -- Backup, Clone Your System Disk Feb-16-2012Ted Whittemore
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Talk on Mirrored System Disk Backups, Backups to the Cloud - iDrive, and Dropbox on Feb 16, 2012, Kinnelon Public Library, NJ -- see the Working Computers Blog Articles:
http://www.kinneloncomputers.com/2012/02/talk-how-to-take-care-of-your-computer.html
and:
http://www.kinneloncomputers.com/2012/02/taking-care-of-your-computer-for-free.html
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The CRB Tech Institute of Clinical Research is a unique year-long education, learning and guidance system for fellows with biology background. It provides a broad education and learning on clinical research methods, research partnerships and managing the demands of family and profession. The goal of CRB Tech Institution is to produce a team of researchers armed with suggestions for clinical research carrying out innovative clinical trials and access to sources to make their concepts a reality.
What is Database Backup? The 3 Important Recovery Techniques from transaction...Raj vardhan
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What is Database Backup?
What is Database recovery techniques
Why recovery is needed? (What causes a Transaction to fail?)
The 3 Important Recovery Techniques from transaction failures:
The figure below illustrates the use of Shadow paging techniques:
Veeam backup Oracle DB in a VM is easy and reliable way to protect dataAleks Y
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Few slides regarding why backing up Oracle DB in a VM with Veeam B&R is easy and reliable way to protect data - easy to backup, easy to recover and restore.
This presentation discusses the following topics:
What is Recovery ?
Database Recovery techniques
System log
Working of Commit and Roll back
Recovery techniques
Backup techniques
This technical presentation by EDB Dave Thomas, Systems Engineer provides an overview of:
1) BGWriter/Writer Process
2) Wall Writer Process
3) Stats Collector Process
4) Autovacuum Launch Process
5) Syslogger Process/Logger process
6) Archiver Process
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UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
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Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
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Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
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Clients donât know what they donât know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clientsâ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
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Neuro-symbolic (NeSy) AI is on the rise. However, simply machine learning on just any symbolic structure is not sufficient to really harvest the gains of NeSy. These will only be gained when the symbolic structures have an actual semantics. I give an operational definition of semantics as âpredictable inferenceâ.
All of this illustrated with link prediction over knowledge graphs, but the argument is general.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
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Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
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Gopinath Rebala
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A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
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I have heard many times that architecture is not important for the front-end. Also, many times I have seen how developers implement features on the front-end just following the standard rules for a framework and think that this is enough to successfully launch the project, and then the project fails. How to prevent this and what approach to choose? I have launched dozens of complex projects and during the talk we will analyze which approaches have worked for me and which have not.
5. Backup and Recovery
Backup and recovery is brought to
mind whenever there is potential
outside threats to a database.
Backup management refers to the
data safety.
5
6. Checkpoints
⢠To recover the database after some failure
we must consult the log record to determine
which transaction needs to be undone and
redone. For this we need to search the entire
log to determine this information. There are
two major problems with this approach.
1. The search process is time-consuming.
2. Most of the transactions need to redone
have already written their updates into the
database.
6
7. Checkpoints
⢠Although redoing them will cause no harm, but it
will make recovery process more time
consuming.
⢠To reduce these types of overhead, we introduce
Check points. The system periodically performs
Checkpoints.
⢠The log file may grow too big to be handled at all.
⢠Checkpoint is a mechanism where all the
previous logs are removed from the system and
stored permanently in a storage disk.
7
8. Actions Performed During
Checkpoints
⢠Output onto stable storage all log records currently residing in
main memory.
⢠Output on the disk all modified buffer blocks.
⢠The presence of a <checkpoint> record makes recovery process
more streamline.
⢠Consider a transaction Ti that committed prior to the
Checkpoint, means that <Ti, Commit> must appear in the log
before the<checkpoint> record.
⢠Any database modifications made by Ti must have been
written to the database either prior to the checkpoint or as
part of checkpoint itself.
8
9. Actions Performed During
Checkpoints
⢠Thus, at recovery time, there is no need to perform a redo
operation on Ti.
⢠The checkpoint record gives a list of all transactions that
were in progress at the time the checkpoint was taken.
Thus, the checkpoints help the system to provide
information at restart time which transaction to undo and
which to redo.
9
11. Example (contd..)
⢠A system failure has occurred at time tf
⢠The most recent checkpoint prior to time tf was taken at time tc
⢠Transactions of type T1 completed (successfully) prior to time tc
⢠Transactions of type T2 started prior to time tc and
completed(successfully) after time tc and before time tf
⢠Transactions of type T3 also started prior to time tc but did not
complete by time tf
⢠Transactions of type T4 started after time tc and
completed(successfully) before time tf.
⢠Finally, transactions of type T5 also started after time tc, but did
not complete by time tf
11
12. Example (contd..)
⢠It should be clear that, in case of immediate modification
technique those transactions that have <Ti, start> and <Ti,
commit> must be redo and those transactions that have only
<Ti, start> and no <Ti, commit> must be undo.
⢠Thus, when the system is restarted in case of immediate
database modification, transactions of types T3 and T5 must
be undone, and transactions of types T2 and T4 must be
redone. Note, however that transactions of type T1 do not
enter in the restart process at all, because their updates were
forced to the database at time tc as part of the checkpoint
process.
12
13. Log-Record Buffering
⢠As, we assumed earlier that every log record is output to
stable storage at the time it is created. This assumption
imposes a high overhead on system execution for the
following reasons:
⢠Output to stable storage is performed in units of blocks. In
most cases, a log record is much smaller than a block. Thus,
the output of each log record translates to a much larger
output at the physical level.
13
14. Log-Record Buffering
⢠To do so, we write log records to a log buffer in main memory,
where they stay temporarily until they are output to stable
storage.
⢠Multiple log records can be gathered in the log buffer and
output to stable storage in a single output operation. The
order of log records in the stable storage must be exactly the
same as the order in which they execute.
⢠The cost of performing the output of a block to storage is
sufficiently high that it is desirable to output multiple log
records at once.
14
15. Log-Record Buffering
⢠Due to the use of log buffering a log record may reside in only
main memory (volatile storage) for a considerable time before it
is output to stable storage. Since such log records are lost if the
system crashes, we must impose additional requirements on the
recovery techniques to ensure transaction atomicity.
⢠Transaction Ti enters the commit state after the <Ti commit> log
record has been output to stable storage.
15
16. Log-Record Buffering
⢠Before the <Ti commit> log record can be output to stable
storage, all log records pertaining to transaction Ti must have
been output to stable storage.
⢠Before a block of data in main memory can be output to the
database (in nonvolatile storage), all log records pertaining to
data in that block must have been output to stable storage.
The latter rule is called the write-ahead logging (WAL) rule.
16
17. Write-Ahead Log Protocol
⢠Before writing a transaction to disk, every update log
record that describes a change to this page must be
forced to stable storage.
⢠This is accomplished by forcing all log records to
stable storage before writing the transaction to disk.
⢠WAL is the fundamental rule that ensures that a
record of every change to the database is available
while attempting to recover from a crash. 17
18. Write-Ahead Log Protocol
⢠In computer science, write-ahead logging (WAL) is
a family of techniques for providing
atomicity and durability (two of
the ACID properties) in database systems. Usually
both redo and undo information is stored in the
log.
⢠Note that the definition of a committed
transaction is effectively âa transaction whose log
records, including a commit record, have all been
written to stable storageâ.
18
19. page 3
page 2
page 4
page 1
page 5
page 6
Recovery: Shadow Paging
Technique
⢠The database is considered to be
made up of a number of n fixed-
size disk blocks or pages, for
recovery purposes.
⢠Current page table points to most
recent current database pages on
disk.
⢠When transaction starts both page
tables are identical for that
transaction.
2
1
3
4
5
6
Shadow page
table
Current
Page table
19
20. page 5 (old)
page 1
page 4
page 2 (old)
page 3
page 6
page 2 (new)
page 5 (new)
2
1
3
4
5
6
Currentpage table
(after updating pages
2,6)
Database data pages (blocks)
2
1
3
4
5
6
Shadowpage table
(notupdated)
Shadow Paging Technique
When a transaction
begins executing
â Once the operations(
write or update) are
completed the current
page table is copied into
a shadow page table.
â shadow page table is
then saved
â shadow page table is
never modified during
transaction execution.
â Current page may
changed during
transaction execution.
20
21. Shadow Paging Technique
⢠To recover from a failure
â the state of the database before
transaction execution is available
through the shadow page table
â free modified pages
â discard current page table
â that state is recovered by reinstating
the shadow page table to become
the current page table once more
⢠Committing a transaction
â discard previous shadow page
â free old page tables that it
references
⢠Garbage collection
page5(old)
page1
page4
page2(old)
page3
page6
page2(new)
page5(new)
2
1
3
4
5
6
Currentpagetable
(afterupdating pages
2,6)
Databasedata pages (blocks)
2
1
3
4
5
6
Shadowpagetable
(notupdated)
21
22. Shadow paging Technique
⢠Shadow paging is an alternative to log-based recovery; this
scheme is useful if transactions execute serially
⢠Idea: maintain two page tables during the lifetime of a
transaction âthe current page table, and the shadow page
table.
⢠Store the shadow page table in nonvolatile storage, such that
state of the database prior to transaction execution may be
recovered.
⢠writes operationsânew copy of page is created and current
page table entry modified to point to new disk page/block.
22
23. Shadow Paging Technique
Whenever any page is about to be written for the first time
â A copy of this page is made onto an unused page.
â The current page table is then made to point to the copy
â The update is performed on the copy
⢠If the shadow is stored in nonvolatile memory and a system
crash occurs, then the shadow page table is copied to the
current page table. This guarantees that the shadow page
table will point to the database pages corresponding to the
state of the database prior to any transaction that was active
at the time of the crash, making aborts automatic.
23
25. Backup Facilities
⢠The facilities provided by DBMS is to produce a back-up
copy (or save) of the entire database.
⢠DBMS normally provides a COPY utility for backup
⢠The back-up facility should create a copy of related
database objects including the database indexes, source
libraries, and so on
Recovery Facilities
25
26. Backup Facilities
⢠It should be periodic. and produced a back-up copy at
least once per day.
⢠The copy should be stored in a secured location where it
is protected from loss or damage.
⢠The back-up copy is used to restore the database in the
event of hardware failure, catastrophic loss, or damage.
Recovery Facilities
26
27. Backup Facilities
⢠Some DBMSs provide back-up utilities for the DBA;
⢠And some systems assume the DBA will use the operating
system commands, export commands, or SELECT ... INTO
SQL commands to perform backups.
Recovery Facilities
27
28. Backup Facilities
⢠Performing the nightly backup for a particular database is
repetitive, creating a script that automates regular backups will
save time.
⢠In a large databases, regular full backups may be impractical,
because the time required to perform the backup may exceed
that available.
Recovery Facilities
28
29. Backup Facilities
⢠Cold backupâdatabase is shut down during backup
⢠Hot backupâselected portion is shut down and backed up at a
given time
Recovery Facilities
29
30. Recovery Manager
⢠It is a module of the DBMS that restores the database to a
correct condition when a failure occurs and then resumes
processing user requests.
⢠The type of restart used depends on the nature of the failure.
Recovery Facilities
30
32. Recovery and Restart Procedures
ďDisk Mirroring
⢠To be able to switch to an existing copy of
the database, the database must be mirrored.
⢠At least two copies of the database must be
kept and updated simultaneously. When a
media failure occurs, processing is switched to
the duplicate copy of the database.
⢠This technique allow the faster recovery.
Recovery Facilities
32
34. Recovery and Restart Procedures
ď Restore/Rerun
⢠It involves reprocessing the day's transactions (up
to the point of failure) against the back-up copy of
the database or portion of the database being
recovered.
⢠First, the database is shut down, and then the most
recent copy of the database or file to be recovered
(say, from the previous day).
Recovery Facilities
34
35. Recovery and Restart Procedures
ď Restore/Rerun
⢠Advantages
⢠Simplicity
⢠No need to create a database change journal or log
file.
⢠Disadvantages
⢠New transaction can not performed until the
recovery is completed.
Recovery Facilities
35
36. Recovery and Restart Procedures
ď˝ Transaction Integrity
⢠A DBMS provides facility of transaction boundary
for maintaining transaction integrity.
⢠Transaction boundaries are logical beginning and
end of transactions.
⢠If the transaction are successful then they are
commits and if transaction fails at any point then
they are aborted.
Recovery Facilities
36
37. Recovery and Restart Procedures
ď˝ Backward Recovery
⢠It is a recovery technique in which unwanted
changes made to database are undo.
⢠Rollback: apply before images
⢠When certain transactions are abnormally
terminated then DBMS recover the database to an
earliest state by applying images records.
Recovery Facilities
37
39. Recovery and Restart Procedures
ď˝ Forward Recovery
(Roll Forward)âapply after images
⢠Starts with an earlier copy of the database. After-
images (the results of good transactions) are
applied to the database, and the database is
quickly moved forward to a later state.
Recovery Facilities
39