Percona xtrabackup - MySQL Meetup @ Mumbai

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Percona Xtrabackup Nilnandan Joshi Support Engineer Percona LLC 2014

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Its related to Percona utilities.

Transcript of Percona xtrabackup - MySQL Meetup @ Mumbai

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Percona Xtrabackup

Nilnandan JoshiSupport EngineerPercona LLC 2014

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Introduction

Percona Xtrabackup provides a fully open-source, free, high-performance, non-blocking backup system for InnoDB or XtraDB tables

It can also backup MyISAM, Archive, Merge, and other SQL-level objects

It is a reliable, widely-used alternative to Oracle's MySQL Enterprise Backup

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Features

Full Binary Backups Incremental backups Open Source (GPL)

Online (non-blocking)* Parallel backups & compression Cost: Free

InnoDB & MyISAM Streaming backups MySQL compatibility

Compressed backups Compact backups MySQL Forks' support

Point-in-time recovery

support

Export individual tables; restore

to a different server

MySQL replication &

Galera support

Incremental backups LRU backups Community Help

Throttling OS buffer optimizations Commercial Support

Partial Backups Encrypted backups Easy migration

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Compatibility

Versions <= 2.0 are compatible with :

Oracle MySQL 5.0, 5.1, 5.5 and 5.6

Equivalent versions of Percona Server, MariaDB, and Drizzle

Version 2.1 is compatible with:

Oracle MySQL 5.1 (plugin version [1] ), 5.5, 5.6

Equivalent versions of Percona Server, MariaDB, and Drizzle

[1] The InnoDB Engine plugin 1.0 is distributed -but not enabled- by default. See:

http://dev.mysql.com/doc/innodb-plugin/1.0/en/innodb-plugin-installation.html

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xtrabackup vs. innobackupex

Percona XtraBackup includes two main executables

xtrabackup is the low level binary that handles the creation and consistency checking of InnoDB backups.

innobackupex is a higher-level Perl wrapper for xtrabackup and is also responsible for the rest of the operations, including the backup of other engines

You usually want to use innobackupex

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xtrabackup vs. innobackupex

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Installation

The most straightforward way is installing the Percona apt or yum repositories

Then install the package with:- yum install percona-xtrabackup- aptitude update && aptitude install percona-

xtrabackup

Other installation options can be found at http://www.percona.com/downloads/XtraBackup/

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Requirements and Limitations

Only fully supported on Linux machines

innobackupex is a Perl script Package should take care of all

dependencies (Perl interpreter, mysql driver, other libraries)

Local access to the MySQL datadir is required

READ, WRITE and EXECUTE filesystem privileges are needed

This makes xtrabackup incompatible with RDS or some web hosting providers

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How Percona XtraBackup Works: Full Backup

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How Percona XtraBackup Works: Full Restore

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Command Line Execution

Minimal options for a full backup:

# innobackupex /path/to/backup/

• Actual backup is stored in a timestamped subdirectory.

• It reads the datadir and innodb paths from my.cnf

• A more complete set of options:

# innobackupex --host=localhost --user=root --password=secret /tmp

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What it looks like

root@nilnandan-Dell-XPS:/var/lib/mysql# sudo innobackupex --user=root --password=root /home/nilnandan/backup

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oyand Percona LLC and/or its affiliates 2009-2013. All Rights Reserved.

This software is published underthe GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

Get the latest version of Percona XtraBackup, documentation, and help resources:http://www.percona.com/xb/p

140709 13:52:04 innobackupex: Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup' as 'root' (using password: YES).140709 13:52:04 innobackupex: Connected to MySQL server140709 13:52:04 innobackupex: Executing a version check against the server...140709 13:52:04 innobackupex: Done.

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Target Directory

root@nilnandan-Dell-XPS:~# ls -al /home/nilnandan/backup/2014-07-09_13-52-04total 77868drwxr-xr-x 6 root root 4096 Jul 9 14:28 .drwxrwxr-x 4 nilnandan nilnandan 4096 Jul 9 14:21 ..-rw-r--r-- 1 root root 356 Jul 9 13:52 backup-my.cnfdrwx------ 2 root root 4096 Jul 9 13:52 dbtest-rw-r----- 1 root root 79691776 Jul 9 13:52 ibdata1drwx------ 2 root root 4096 Jul 9 13:52 mysqldrwxr-xr-x 2 root root 4096 Jul 9 13:52 performance_schemadrwx------ 2 root root 4096 Jul 9 13:52 test-rw-r----- 1 root root 95 Jul 9 13:52 xtrabackup_checkpoints-rw-r--r-- 1 root root 528 Jul 9 13:52 xtrabackup_info-rw-r----- 1 root root 2560 Jul 9 13:52 xtrabackup_logfileroot@nilnandan-Dell-XPS:~#

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Files in Target Directory

Hierarchy of files and directories mirroring the original database structure.

backup-my.cnf: Not a backup of the server configuration. It only contains the minimal InnoDB settings at the time the backup to execute the --apply-log phase

xtrabackup_info: Contains all informations about xtrabackup binary, server version, start and end time of backup, binlog position etc.

xtrabackup_checkpoints: Metadata about the backup (type of backup, lsn, etc.)

xtrabackup_logfile: Data needed for the --apply-log phase

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Preparation Phase

Before the backup directory can be used, we must:

Make sure that the InnoDB tablespaces have consistent,non-corrupt data

Create new transaction logs

innobackupex executes xtrabackup twice:

First, to do a controlled crash recovery, applying the log entries with xtrabackup's embedded InnoDB. This redoes all written committed transactions and undoes uncommitted ones.

Second, to create the empty logs

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Preparation Phase (cont)

Only xtrabackup/innobackupex and the backup directory are needed

It can be done on different machine than the original server (we have the xtrabackup binary and the innodb configuration parameters)

Generally, you do it just before restore. If you only do full backups and want to minimize the MTTR (Mean Time To Recover), you can prepare immediately after backup

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Command Line Execution

The simplest form:

$ innobackupex --apply-log/media/backups/2017-07-08_13-22-12

You may specify a memory parameter:

$ innobackupex –apply-log --use-memory=4G/media/backups/2017-07-08_13-22-12

this increases the available buffer pool for the recovery phase (100M by default), to improve performance

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How It Looks Like

nilnandan@nilnandan-Dell-XPS:~/backup$ sudo innobackupex --apply-log 2014-07-09_13-52-04

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oyand Percona LLC and/or its affiliates 2009-2013. All Rights Reserved.

This software is published underthe GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

Get the latest version of Percona XtraBackup, documentation, and help resources:http://www.percona.com/xb/p

IMPORTANT: Please check that the apply-log run completes successfully. At the end of a successful apply-log run innobackupex prints "completed OK!".

140710 10:06:57 innobackupex: Starting ibbackup with command: xtrabackup --defaults-file="/home/nilnandan/backup/2014-07-09_13-52-04/backup-my.cnf" --defaults-group="mysqld" --prepare --target-dir=/home/nilnandan/backup/2014-07-09_13-52-04 --tmpdir=/tmp

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Restore

After --apply-log, we have a consistent full raw backup

We can just move it back to the datadir with standard OS commands once the server is shut down

As a physical backup, restoration is as fast as you can copy the directory contents to the local filesystem

There are specific commands for restoration in XtraBackup

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Copy Back

The integrated command to restore a backup is:

# innobackupex --copy-back /media/backups/2017-07-08_13-22-12

It complains if the datadir, as read from the config file, is not empty [1] (it will not overwrite existing data)

Only partial restores can be done to a running server

xtrabackup_* files are not needed

[1] We can override this behavior with the option --force-non-empty-directories , but it will never overwrite existent files

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What It Looks Like

root@nilnandan-Dell-XPS:~# sudo innobackupex --copy-back /home/nilnandan/backup/2014-07-09_13-52-04/...innobackupex: Starting to copy files in '/home/nilnandan/backup/2014-07-09_13-52-04'innobackupex: back to original data directory '/var/lib/mysql'innobackupex: Copying '/home/nilnandan/backup/2014-07-09_13-52-04/xtrabackup_info' to '/var/lib/mysql/xtrabackup_info'innobackupex: Creating directory '/var/lib/mysql/mysql'innobackupex: Copying '/home/nilnandan/backup/2014-07-09_13-52-04/mysql/time_zone_leap_second.frm' to ...innobackupex: Starting to copy InnoDB log filesinnobackupex: in '/home/nilnandan/backup/2014-07-09_13-52-04'innobackupex: back to original InnoDB log directory '/var/lib/mysql'innobackupex: Copying '/home/nilnandan/backup/2014-07-09_13-52-04/ib_logfile1' to '/var/lib/mysql/ib_logfile1'innobackupex: Copying '/home/nilnandan/backup/2014-07-09_13-52-04/ib_logfile0' to '/var/lib/mysql/ib_logfile0'innobackupex: Finished copying back files.

140710 11:04:12 innobackupex: completed OK!root@nilnandan-Dell-XPS:~#

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Move Back

As an alternative to --copy-back, we can also do:

# innobackupex --move-back /media/backups/2017-07-08_13-22-12

This may be faster or more convenient if the backup is already on the same partition or don't have enough free space

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Restoring Permissions

After restore, as file permissions are preserved, youwill probably have to fix file ownership:

# chown -R mysql:mysql /var/lib/mysql

If MySQL cannot write to the data directory or some of it files, it will refuse to start

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Incremental Backup

Differential & Incremental Backups

Differential backup: saves only the difference in the data since the last full backup

Incremental backup: saves only the difference in the data since the last backup (full or another incremental)

Xtrabackup can perform both, which can lead to an important save in space (and potentially, time), specially if the backups are very frequent or the database is very static

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Incremental Backup(cont..)

Differential and incremental backups work thesame way with xtrabackup:

Every page stores the Log Sequence Number (LSN) when it was last changed

Only pages that have a higher LSN than the base backup (full or incremental) are copied

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Incremental Backup(cont..)

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Incremental Backup(cont..)

Restoration of Incremental Backups

On prepare time, the new pages have to be applied in order to the full backup before restore

This is the reason why you want to wait to fully apply the log just before restore time

Uncommitted transactions must not be undone, as they may have finished on a subsequent incremental backup

Intermediate backups have to apply changes with the option --redo-only

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Incremental Backup(cont..)

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Partial Backups

When using xtrabackup (or innobackupex), we can filter out some of the tables, effectively copying only some databases or tables

Two main restrictions apply for InnoDB tables:

Original database must use innodb_file_per_table, as xtrabackup works at filesystem level

Recovering individual tables is only possible for MySQL 5.6. Previous versions require Percona XtraDB extensions with tablespace import enabled

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Partial Backups (cont..)

Command Line Options for Segmented Backups:

--include : Matches the fully qualified name (database.table) against a regular expression

--databases : Matches a list of databases (or tables) separated by spaces.

--tables-file : Matches a list of tables, one per line, stored on the specified file

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Partial Backups (cont..)

Examples

Backup only the test database:

# innobackupex --include=^test[.] /data/backups

Backup all except the mysql database*:$ mysql -e "SELECT concat(table_schema, '.',table_name) from information_schema.tables WHEREtable_schema NOT IN ('mysql', 'performance_schema','information_schema')" > /tmp/tables

# innobackupex --tables-file=/tmp/tables /data/backups

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Streaming

Xtrabackup allows the streaming of the backup filesto the UNIX standard output

This allows to post-process them or send them to aremote location while the backup is ongoing

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Streaming (cont..)

The stream option accepts two parameters:

--stream=tarIt sends all files to the standard output in the tararchive format (single file without compression)

--stream=xbstreamThe standard output will using the new includedxbstream format, which allows simultaneouscompression, encryption and parallelization

A temporal file path is still required

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Streaming (cont..)

Using tar:

# innobackupex --stream=tar /tmp > backup.tar# innobackupex --stream=tar /tmp | \bzip2 - > backup.tar.bz2

To extract, the tar -i option (ignore zeros) must beused:

# tar -xivf backup.tar# tar -jxif backup.tar.bz2

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Streaming (cont..)

Using xbstream

# innobackupex --stream=xbstream /tmp > \backup.xbstream

To extract, use the xbstream binary provided withPercona Xtrabackup:

# xbstream -x < backup.xbstream -C /root

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Compression

We can use --compress to produce quicklz-compressed files:

# innobackupex --compress /media/backups

To decompress, we can use --decompress orqpress* to decompress the individual .qp filesmanually:

# innobackupex --decompress \/media/backups/2017-07-08_13-22-12

# find . -name "*.qp" -execdir qpress -d \{\} . \;

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Compression and xbstream

The --compress flag can be combined withxbstream (not with tar):

# innobackupex --compress --stream=xbstream /tmp \> /media/backups/backup.xbstream

Before preparation, we must use first xbstream,then decompress:

# xbstream -x -C /media/backups < backup.xbstream# innobackupex --decompress /media/backups

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Parallel Copy and Compression

If using xbstream, we can use --parallel to archiveseveral files at the same time:

# innobackupex --parallel=4 --stream=xbstream \/tmp > /media/backups/backup.tar

If we are using compression, we can parallelize theprocess for each file with –compress-threads

# innobackupex --compress --compress-threads=8 \--stream=xbstream /tmp > /media/backups/backup.tar

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Remote Backups

xtrabackup can send automatically the backup filesto a remote host by redirecting the output toapplications like ssh or netcat:

# innobackupex --stream=tar /tmp \| ssh user@host "cat - > \/media/backups/backup.tar"

# ssh user@host "( nc -l 9999 > \/media/backups/backup.tar & )" \&& innobackupex --stream=tar /tmp \| nc host 9999

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Throttling Remote Backups

pv (pipe viewer) utility can be useful for bothmonitoring and limiting the bandwidth of the copyprocess

The following limits the transmission to 10MB/s:# innobackupex --stream=tar ./ \| pv -q -L10m \| ssh user@desthost \"cat - > /media/backups/backup.tar"

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Compact Backups

In order to reduce backup size, we can skip the copyof secondary index pages:

# innobackupex --compact /media/backups

The space saved will depend on the size of thesecondary indexes. For example:

#backup size without --compact2.0G 2018-02-01_10-18-38#backup size taken with --compact option1.4G 2018-02-01_10-29-48

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Preparing Compact Backups

The downside of compact backups is that theprepare phase will take longer, as the secondarykeys have to be regenerated ( --rebuild-indexes ):

# cat xtrabackup_checkpointsbackup_type = full-backupedfrom_lsn = 0to_lsn = 9541454813last_lsn = 9541454813compact = 1

# innobackupex --apply-log --rebuild-indexes/media/backups/2017-07-08_13-22-12

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Rebuilding Indexes

The --rebuild-threads option can be used to speed up the recreation of the keys, by doing it in parallel:

# innobackupex --apply-log \ --rebuild-indexes --rebuild-threads=8 \ /media/backups/2017-07-08_13-22-12

Rebuilding indexes has the side effect of defragmenting them, as they are done in order. We

can rebuild regular full-backups, too.

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Encrypted Backups

Xtrabackup has support for symmetric encryptionthrough the libgcrypt library for both local andxbstream backups

Before using encryption, a key must be generated.For example, to create an SHA256 key: # openssl enc -aes-256-cbc -pass pass:mypass -P -md

sha1 salt=9C8CE740FD0FE6AD key=0A632731C0EABA6131B6683068E04629524FC8FC1E0F69037D5ED03AF126BD0B

iv =03E872849A8DA83647A5FCEFDF1C68F2

* Please note that specifying passwords on the command line input is considered insecure.

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Encrypted Backups (cont..)

We can now use the previous value of iv as ourencryption key:$ innobackupex --encrypt=AES256 \ --encrypt-

key="03E872849A8DA83647A5FCEFDF1C68F2" \/data/backups

Options:--encryption : Defines the algorithm to be used

(supports AES128, AES192 and AES256)--encrypt-key : Defines the encryption key to use

directly on the command line.--encrypt-key-file : Defines the encryption key by

pointing to a file that contains it. This is recommended over the encrypt-key option

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Speeding up Encryption

Parallel encryption is possible by encrypting morethan one file at a time (--parallel) and using more than one

thread for each file (--encrypt-threads):

# innobackupex --encrypt=AES256 \--encryption-key-file=/media/backups/keyfile--stream=xbstream --encrypt-threads=4 /tmp \> /media/backups/backup.xbstream

We can also change the buffer for each encryption thread with --encrypt-chunk-size (default 64K)

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Decrypting Backups

Before preparing it, the backup must be unarchived (ifxbstream was used) and decrypted. We can use --decrypt or

do it for each individual .xbscript file using xbscript (included with xtrabackup):

# innobackupex --decrypt=AES256 \--encrypt-key="A1EDC73815467C083B0869508406637E" \/data/backups/2013-08-01_08-31-35/

# for i in `find . -iname "*\.xbcrypt"`; do \xbcrypt -d --encrypt-key-file=/media/backups/filekey \--encrypt-algo=AES256 < $i \> $(dirname $i)/$(basename $i .xbcrypt) && rm $i; done

--parallel can speed up the process as well

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TROUBLESHOOTING ANDPERFORMANCE

Locking Issues By default, innobackupex will lock the tables (FTWRL)

during the last phase of the backup You can use --no-lock if you are only backing upInnoDB tables and no DDL are executing on that lastPhase* You can use --no-lock if you backup other engines if no

DDLs are executed, and non-innodb tables are not modified (e.g. users are created on the mysql database)*\

You can use --rsync to minimize the copy time whenlocked

* Please note that --no-lock also makes impossible to obtain a reliable binary log coordinates.

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TROUBLESHOOTING ANDPERFORMANCE

File Not Found

2017-07-08 12:56:56 7f0dfe4737e0 InnoDB: Operating system error number 2 in a file operation.

InnoDB: The error means the system cannot find the path specified.2017-07-08 12:56:56 7f0dfe4737e0 InnoDB: File name ./ibdata12017-07-08 12:56:56 7f0dfe4737e0 InnoDB: File operation call: 'open'returned OS error 71.2017-07-08 12:56:56 7f0dfe4737e0 InnoDB: Cannot continue operation.innobackupex: Error: ibbackup child process has died at /usr/bin/innobackupex line 389.

Set a correct datadir option on /etc/my.cnf

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TROUBLESHOOTING ANDPERFORMANCE

Permission Denied

InnoDB: read-write can't be opened in ./ibdata1 modextrabackup: Could not open or create data files.[...]xtrabackup: error: xb_data_files_init() failed witherror code 1000innobackupex: Error: ibbackup child process has died at /usr/bin/innobackupex line 389.innobackupex: Error: Failed to create backup directory /backups/2017-07-08_12-19-01: Permission denied at /usr/bin/innobackupex line 389.

Use the Linux root user or any other account with read/write permissions on datadir and on target-dir

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TROUBLESHOOTING ANDPERFORMANCE

MySQL Does Not Start AfterRecovery

Starting MySQL server... FAILEDThe server quit without updating PID file

Did you change file permissions of the files to the mysql user?

Did you remember to apply the log before restart?Failing to do so can also corrupt the backup.

Did you restore an appropriate my.cnf file? Previousversions of MySQL (< 5.6) do not start if transaction log

files have a different size than specified/default

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TROUBLESHOOTING ANDPERFORMANCE

The Backup Takes Too Long

As MySQL performs physical backups, the speedshould be close to to a filesystem copy. If IO impactis not a concern, we can speed it up by:

Using parallelization ( --parallel , --compression-threads , --encrypt-threads , --rebuild-threads ) Using compression ( --compress ) if the extra CPUcompensates the lower bandwidth required Using incremental backups (specially with Perconaextensions) to perform rolling full backups

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