与Oracle相比，其他开源软件基本都未自带物理备份软件或者功能不够完整，要实现物理备份需借助三方插件完成。Postgresql虽然自带pg_basebackup，但是不支持增量备份。pg_rman是pgsql众多三方备份插件之一，其支持全量备份、增量备份、归档备份等，其功能类似oraclerman。

pg_rman下载地址:https://github.com/ossc-db/pg_rman/releases,下载对应pg版本的rpm文件或者源码包文件。rpm或者源码编译均依赖于zlib-devel包，所以需提前安装。

源码安装方法如下：

make

makeinstall

makeinstallcheck

pg数据库要进行物理备份，跟oracle一样，需开启归档功能，操作步骤如下：

altersystem set wal_level=replica;

altersystem set archive_mode=on;

altersystem set archive_command = cp %p .../archive/%f;

重启数据库。

开始备份前，还需进行catalog初始化，用于保存备份信息，类似oracle控制文件或者catalog里保留的备份信息，命令如下：

pg_rmaninit -B /backup

[postgres@guassdb1~]$ pg_rman init

WARNING:ARCLOG_PATH is not set yet

DETAIL:The archive_command is not set in postgresql.conf.

HINT:Please set ARCLOG_PATH in pg_rman.ini or environmental variable.

INFO:SRVLOG_PATH is set to /data/pgdata1/pg_log

完成catalog初始化后，即可开始数据库备份。值得说明的是在catalog中有pg_rman.ini文件，可配置备份的环境变量、备份选项、备份集保留期限等信息，其功能类似oraclerman 的configure和showall。

pg_rman.ini示例：

[postgres@spcl-****:spc**_back]$cat pg_rman.ini

ARCLOG_PATH=/backup/s***dp_arch

SRVLOG_PATH=/data/s***dp_data/log

1、数据库全备

[postgres@guassdb1backup]$ pg_rman backup -b full -A /pg_archivelog

INFO:copying database files

INFO:copying archived WAL files

INFO:backup complete

INFO:Please execute pg_rman validate to verify the files are correctlycopied.

[postgres@guassdb1backup]$ pg_rman show

=====================================================================

StartTime          EndTime              Mode    Size   TLI  Status

=====================================================================

2020-10-2516:24:17  2020-10-25 16:24:20  FULL    95MB     1  DONE

---由上面红色字体可看出备份成功后，其状态是done，还需要进行validate操作后，备份集才可用于恢复，增量备份才会用于做对比。

[postgres@guassdb1~]$ pg_rman validate

INFO:validate: "2020-10-25 16:24:17" backup and archive logfiles by CRC

INFO:backup "2020-10-25 16:24:17" is valid

[postgres@guassdb1~]$

[postgres@guassdb1~]$

[postgres@guassdb1~]$

[postgres@guassdb1~]$ pg_rman show detail

======================================================================================================================

StartTime          EndTime              Mode    Data  ArcLog  SrvLog   Total Compressed  CurTLI  ParentTLI  Status

======================================================================================================================

2020-10-2516:24:17  2020-10-25 16:24:20  FULL    41MB    67MB    ----    95MB      false       1          0  OK

--validate校验完成后，其备份集状态变成OK

备份完成后备份集文件的目录结构如下：

2、增量备份

pg_rmanbackup -b incremental -A /pg_archivelog

在生产环境中，需制定备份策略，通常每周全备，每天增量，同时备份归档日志，备份脚本示例：

每周日全备，其他时间进行增量备份

#/bin/bash

.~/.bash_profile

current_path=`dirname$0`

exportPGPASSWORD=*****

exportBACKUP_PATH=/backup***_back

LOCAL_HOST=**.**.**.**

LOCAL_PORT=5432

BACK_DAY=6

#主库角色备份

master_backup(){

echo"master_backup"

pg_rmanbackup --backup-mode=$1 -Z -F -h ${LOCAL_HOST} -p ${LOCAL_PORT}--with-serverlog --keep-srvlog-days=7 --keep-data-generations=1--keep-arclog-files=100 --keep-arclog-days=1 -U postgres -Pv

#写入文件短信告警

if[[ $? -ne 0 ]]; then

echo`date +%y-%m-%d %H:%M:%S: ` $1 "backup failed!" >${current_path}/backupflag

else

echo`date +%y-%m-%d %H:%M:%S: ` $1 "backup successful!" >${current_path}/backupflag

pg_rmanvalidate

pg_rmanpurge

fi

}

#从库角色备份

slave_backup(){

echo"slave_backup"

pg_rmanbackup --backup-mode=$1 -Z -F -h $2 -p $3--standby-host=${LOCAL_HOST} --standby-port=${LOCAL_PORT}--with-serverlog --keep-srvlog-days=7 --keep-data-generations=1--keep-arclog-files=100 --keep-arclog-days=1 -U postgres -Pv

#写入文件短信告警

if[[ $? -ne 0 ]]; then

echo`date +%y-%m-%d %H:%M:%S: ` $1 "backup failed!" >${current_path}/backupflag

else

echo`date +%y-%m-%d %H:%M:%S: ` $1 "backup successful!" >${current_path}/backupflag

pg_rmanvalidate

pg_rmanpurge

fi

}

#判断日期,如周六全备,其它时间备份归档,若没有全量备份，则做全量备份

fullback_stat=`pg_rmanshow |grep "FULL"|awk {print $8}`

weekday=`date+%w`

if[[ ${fullback_stat} =~ "OK" ]]; then

if[[ ${weekday} -eq ${BACK_DAY} ]]; then

back_mode=full

else

back_mode=incremental

fi

else

back_mode=full

fi

#数据库进程情况

is_alive=`pg_isready-p ${LOCAL_PORT}|grep "accepting"|wc -l`

if[[ $is_alive -eq 0 ]]; then

echo"database is down"

else

#主从

is_recovery=`psql-t -c "SELECT pg_is_in_recovery();"`

echo${is_recovery}

if[[ ${is_recovery}  =~ "t" ]]; then

masterhost=`psql-t -c "select sender_host from pg_stat_wal_receiver;"`

masterport=`psql-t -c "select sender_port from pg_stat_wal_receiver;"`

logger-i "slave_backup will be running"

slave_backup${back_mode} ${masterhost} ${masterport}

else

logger-i "master_backup will be running"

master_backup${back_mode}

fi

fi