PostgreSQL的HA解决方案-1主从和备份（master/slave and backup）
一.部署说明
1.1 实施环境
本文档实验环境如下：
PGSQL主机: 192.168.1.45
PGSQL备机: 192.168.1.50
软件和系统版本
Pgsql 版本: pgsql 9.2.4
Linux 版本: Redhat 5.8
1.2 文档说明
本文档详细说明了PG的双机扩展，使pgsql数据库具备双机热备流复制功能。注意，双机热备中存在主从关系，这样才能保证数据的一直性，主机操作都可以，但从机只能用作查询。所以热备的意义在于分担主机的查询压力，备份主机数据，当主机出问题后，从机稍加修改就可以变为主机。
为了试验减少不必要的麻烦，本系列试验中，各个主机之间的通信，都是设置为无密码访问，但对于实际生产，需要根据实际需要，配置密码，增强集群的安全性。
二.配置步骤
1.1 （主从一样）。编辑data/pg_hba.conf 访问控制文件。
在配置pgsql之前，首先要设置两台服务器使得postgres用户可以无密码相互访问。 配置过程一定要分清主从机。因为实验的两台虚拟机所在网段都是192.168.1.0/24.所以，新增如下：
# TYPE DATABASE USER ADDRESS METHOD # "local" is for Unix domain socket connections only local all all trust # IPv4 local connections: host all all 127.0.0.1/32 trust host all all 192.168.1.0/24 trust # IPv6 local connections: host all all ::1/128 trust # Allow replication connections from localhost, by a user with the # replication privilege. #local replication postgres trust #host replication postgres 127.0.0.1/32 trust host replication postgres 192.168.1.0/24 trust #host replication postgres ::1/128 trust
1.2 （主从一样）。编辑data/postgresql.conf 数据库配置文件。
主从机的数据库postgresql.conf配置相同，主要是方便接下来的将主机的data文件直接备份还原到从机，并且也方便将来主从切换。请对照默认参数设置，设置相应参数，一些参数的设置，如
max_connections = 100 #最大连接数的设置，当超过最大链接时，数据库拒绝访问。
shared_buffers = 1280MB #共享内存，主要是和服务器的硬件和实际的项目需求相关，理论上在硬件资源允许的情况下，此值越大越好。
wal_level = hot_standby #开启主从热备模式
fsync = on #异步数据同步
full_page_writes = on
checkpoint_segments = 32 #关于脏数据写回的
archive_mode = on #打开归档模式
archive_command ='cp %p /opt/bjca3/pgsql/data/archive/%f ' #将归档文件保存在data/archive目录下
max_wal_senders = 2 #根据从机的个数设置，实验中只有一个从机，所以只设置为1
wal_keep_segments = 250
hot_standby = on #在配置中，并不是每个配置都起作用的，数据库会根据当前的主从机的属性，自动判断哪些是主机的配置，哪些是从机的配置，配置文档中也有说明。
max_standby_archive_delay = 300s
max_standby_streaming_delay = 300s
wal_receiver_status_interval = 10s
hot_standby_feedback = on
log_line_prefix = '[%t] '
详细的配置及含义请看下边的配置文件。
# ----------------------------- # PostgreSQL configuration file # ----------------------------- # # This file consists of lines of the form: # # name = value # # (The "=" is optional.) Whitespace may be used. Comments are introduced with # "#" anywhere on a line. The complete list of parameter names and allowed # values can be found in the PostgreSQL documentation. # # The commented-out settings shown in this file represent the default values. # Re-commenting a setting is NOT sufficient to revert it to the default value; # you need to reload the server. # # This file is read on server startup and when the server receives a SIGHUP # signal. If you edit the file on a running system, you have to SIGHUP the # server for the changes to take effect, or use "pg_ctl reload". Some # parameters, which are marked below, require a server shutdown and restart to # take effect. # # Any parameter can also be given as a command-line option to the server, e.g., # "postgres -c log_connections=on". Some parameters can be changed at run time # with the "SET" SQL command. # # Memory units: kB = kilobytes Time units: ms = milliseconds # MB = megabytes s = seconds # GB = gigabytes min = minutes # h = hours # d = days #------------------------------------------------------------------------------ # FILE LOCATIONS #------------------------------------------------------------------------------ # The default values of these variables are driven from the -D command-line # option or PGDATA environment variable, represented here as ConfigDir. #data_directory = 'ConfigDir' # use data in another directory # (change requires restart) #hba_file = 'ConfigDir/pg_hba.conf' # host-based authentication file # (change requires restart) #ident_file = 'ConfigDir/pg_ident.conf' # ident configuration file # (change requires restart) # If external_pid_file is not explicitly set, no extra PID file is written. #external_pid_file = '' # write an extra PID file # (change requires restart) #------------------------------------------------------------------------------ # CONNECTIONS AND AUTHENTICATION #------------------------------------------------------------------------------ # - Connection Settings - #listen_addresses = 'localhost' # what IP address(es) to listen on; listen_addresses = '*' # what IP address(es) to listen on; # comma-separated list of addresses; # defaults to 'localhost'; use '*' for all # (change requires restart) #port = 5432 # (change requires restart) port = 5432 # (change requires restart) max_connections = 100 # (change requires restart) # Note: Increasing max_connections costs ~400 bytes of shared memory per # connection slot, plus lock space (see max_locks_per_transaction). #superuser_reserved_connections = 3 # (change requires restart) #unix_socket_directory = '' # (change requires restart) #unix_socket_group = '' # (change requires restart) #unix_socket_permissions = 0777 # begin with 0 to use octal notation # (change requires restart) #bonjour = off # advertise server via Bonjour # (change requires restart) #bonjour_name = '' # defaults to the computer name # (change requires restart) # - Security and Authentication - #authentication_timeout = 1min # 1s-600s #ssl = off # (change requires restart) #ssl_ciphers = 'ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH' # allowed SSL ciphers # (change requires restart) #ssl_renegotiation_limit = 512MB # amount of data between renegotiations #ssl_cert_file = 'server.crt' # (change requires restart) #ssl_key_file = 'server.key' # (change requires restart) #ssl_ca_file = '' # (change requires restart) #ssl_crl_file = '' # (change requires restart) #password_encryption = on #db_user_namespace = off # Kerberos and GSSAPI #krb_server_keyfile = '' #krb_srvname = 'postgres' # (Kerberos only) #krb_caseins_users = off # - TCP Keepalives - # see "man 7 tcp" for details #tcp_keepalives_idle = 0 # TCP_KEEPIDLE, in seconds; # 0 selects the system default #tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds; # 0 selects the system default #tcp_keepalives_count = 0 # TCP_KEEPCNT; # 0 selects the system default #------------------------------------------------------------------------------ # RESOURCE USAGE (except WAL) #------------------------------------------------------------------------------ # - Memory - #shared_buffers = 32MB # min 128kB shared_buffers = 256MB # min 128kB # (change requires restart) #temp_buffers = 8MB # min 800kB #max_prepared_transactions = 0 # zero disables the feature # (change requires restart) # Note: Increasing max_prepared_transactions costs ~600 bytes of shared memory # per transaction slot, plus lock space (see max_locks_per_transaction). # It is not advisable to set max_prepared_transactions nonzero unless you # actively intend to use prepared transactions. #work_mem = 1MB # min 64kB #maintenance_work_mem = 16MB # min 1MB #max_stack_depth = 2MB # min 100kB # - Disk - #temp_file_limit = -1 # limits per-session temp file space # in kB, or -1 for no limit # - Kernel Resource Usage - #max_files_per_process = 1000 # min 25 # (change requires restart) #shared_preload_libraries = '' # (change requires restart) # - Cost-Based Vacuum Delay - #vacuum_cost_delay = 0ms # 0-100 milliseconds #vacuum_cost_page_hit = 1 # 0-10000 credits #vacuum_cost_page_miss = 10 # 0-10000 credits #vacuum_cost_page_dirty = 20 # 0-10000 credits #vacuum_cost_limit = 200 # 1-10000 credits # - Background Writer - #bgwriter_delay = 200ms # 10-10000ms between rounds #bgwriter_lru_maxpages = 100 # 0-1000 max buffers written/round #bgwriter_lru_multiplier = 2.0 # 0-10.0 multipler on buffers scanned/round # - Asynchronous Behavior - #effective_io_concurrency = 1 # 1-1000; 0 disables prefetching #------------------------------------------------------------------------------ # WRITE AHEAD LOG #------------------------------------------------------------------------------ # - Settings - #wal_level = minimal # minimal, archive, or hot_standby wal_level = hot_standby # minimal, archive, or hot_standby # (change requires restart) #fsync = on # turns forced synchronization on or off fsync = on # turns forced synchronization on or off #synchronous_commit = on # synchronization level; # off, local, remote_write, or on #wal_sync_method = fsync # the default is the first option # supported by the operating system: # open_datasync # fdatasync (default on Linux) # fsync # fsync_writethrough # open_sync #full_page_writes = on # recover from partial page writes full_page_writes = on # recover from partial page writes #wal_buffers = -1 # min 32kB, -1 sets based on shared_buffers # (change requires restart) #wal_writer_delay = 200ms # 1-10000 milliseconds #commit_delay = 0 # range 0-100000, in microseconds #commit_siblings = 5 # range 1-1000 # - Checkpoints - #checkpoint_segments = 3 # in logfile segments, min 1, 16MB each #checkpoint_timeout = 5min # range 30s-1h #checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0 #checkpoint_warning = 30s # 0 disables # - Archiving - #archive_mode = off # allows archiving to be done archive_mode = on # allows archiving to be done # (change requires restart) #archive_command = '' # command to use to archive a logfile segment archive_command = 'cp %p /usr/local/pgsql/data/archive/%f' # command to use to archive a logfile segment # placeholders: %p = path of file to archive # %f = file name only # e.g. 'test ! -f /mnt/server/archivedir/%f && cp %p /mnt/server/archivedir/%f' #archive_timeout = 0 # force a logfile segment switch after this # number of seconds; 0 disables #------------------------------------------------------------------------------ # REPLICATION #------------------------------------------------------------------------------ # - Sending Server(s) - # Set these on the master and on any standby that will send replication data. #max_wal_senders = 0 # max number of walsender processes max_wal_senders = 1 # max number of walsender processes # (change requires restart) #wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables wal_keep_segments = 250 # in logfile segments, 16MB each; 0 disables #replication_timeout = 60s # in milliseconds; 0 disables # - Master Server - # These settings are ignored on a standby server. #synchronous_standby_names = '' # standby servers that provide sync rep synchronous_standby_names = '*' # standby servers that provide sync rep # comma-separated list of application_name # from standby(s); '*' = all #vacuum_defer_cleanup_age = 0 # number of xacts by which cleanup is delayed # - Standby Servers - # These settings are ignored on a master server. #hot_standby = off # "on" allows queries during recovery hot_standby = on # "on" allows queries during recovery # (change requires restart) #max_standby_archive_delay = 30s # max delay before canceling queries max_standby_archive_delay = 300s # max delay before canceling queries # when reading WAL from archive; # -1 allows indefinite delay #max_standby_streaming_delay = 30s # max delay before canceling queries max_standby_streaming_delay = 300s # max delay before canceling queries # when reading streaming WAL; # -1 allows indefinite delay #wal_receiver_status_interval = 10s # send replies at least this often wal_receiver_status_interval = 10s # send replies at least this often # 0 disables #hot_standby_feedback = off # send info from standby to prevent hot_standby_feedback = on # send info from standby to prevent # query conflicts #------------------------------------------------------------------------------ # QUERY TUNING #------------------------------------------------------------------------------ # - Planner Method Configuration - #enable_bitmapscan = on #enable_hashagg = on #enable_hashjoin = on #enable_indexscan = on #enable_indexonlyscan = on #enable_material = on #enable_mergejoin = on #enable_nestloop = on #enable_seqscan = on #enable_sort = on #enable_tidscan = on # - Planner Cost Constants - #seq_page_cost = 1.0 # measured on an arbitrary scale #random_page_cost = 4.0 # same scale as above #cpu_tuple_cost = 0.01 # same scale as above #cpu_index_tuple_cost = 0.005 # same scale as above #cpu_operator_cost = 0.0025 # same scale as above #effective_cache_size = 128MB # - Genetic Query Optimizer - #geqo = on #geqo_threshold = 12 #geqo_effort = 5 # range 1-10 #geqo_pool_size = 0 # selects default based on effort #geqo_generations = 0 # selects default based on effort #geqo_selection_bias = 2.0 # range 1.5-2.0 #geqo_seed = 0.0 # range 0.0-1.0 # - Other Planner Options - #default_statistics_target = 100 # range 1-10000 #constraint_exclusion = partition # on, off, or partition #cursor_tuple_fraction = 0.1 # range 0.0-1.0 #from_collapse_limit = 8 #join_collapse_limit = 8 # 1 disables collapsing of explicit # JOIN clauses #------------------------------------------------------------------------------ # ERROR REPORTING AND LOGGING #------------------------------------------------------------------------------ # - Where to Log - #log_destination = 'stderr' # Valid values are combinations of log_destination = 'stderr' # Valid values are combinations of # stderr, csvlog, syslog, and eventlog, # depending on platform. csvlog # requires logging_collector to be on. # This is used when logging to stderr: #logging_collector = off # Enable capturing of stderr and csvlog logging_collector = on # Enable capturing of stderr and csvlog # into log files. Required to be on for # csvlogs. # (change requires restart) # These are only used if logging_collector is on: #log_directory = 'pg_log' # directory where log files are written, log_directory = 'pg_log' # directory where log files are written, # can be absolute or relative to PGDATA #log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern, log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log' # log file name pattern, # can include strftime() escapes #log_file_mode = 0600 # creation mode for log files, # begin with 0 to use octal notation #log_truncate_on_rotation = off # If on, an existing log file with the # same name as the new log file will be # truncated rather than appended to. # But such truncation only occurs on # time-driven rotation, not on restarts # or size-driven rotation. Default is # off, meaning append to existing files # in all cases. #log_rotation_age = 1d # Automatic rotation of logfiles will # happen after that time. 0 disables. #log_rotation_size = 10MB # Automatic rotation of logfiles will # happen after that much log output. # 0 disables. # These are relevant when logging to syslog: #syslog_facility = 'LOCAL0' #syslog_ident = 'postgres' # This is only relevant when logging to eventlog (win32): #event_source = 'PostgreSQL' # - When to Log - #client_min_messages = notice # values in order of decreasing detail: # debug5 # debug4 # debug3 # debug2 # debug1 # log # notice # warning # error #log_min_messages = warning # values in order of decreasing detail: # debug5 # debug4 # debug3 # debug2 # debug1 # info # notice # warning # error # log # fatal # panic #log_min_error_statement = error # values in order of decreasing detail: # debug5 # debug4 # debug3 # debug2 # debug1 # info # notice # warning # error # log # fatal # panic (effectively off) #log_min_duration_statement = -1 # -1 is disabled, 0 logs all statements # and their durations, > 0 logs only # statements running at least this number # of milliseconds # - What to Log - #debug_print_parse = off #debug_print_rewritten = off #debug_print_plan = off #debug_pretty_print = on #log_checkpoints = off #log_connections = off #log_disconnections = off #log_duration = off #log_error_verbosity = default # terse, default, or verbose messages #log_hostname = off #log_line_prefix = '[%t]' # special values: # %a = application name # %u = user name # %d = database name # %r = remote host and port # %h = remote host # %p = process ID # %t = timestamp without milliseconds # %m = timestamp with milliseconds # %i = command tag # %e = SQL state # %c = session ID # %l = session line number # %s = session start timestamp # %v = virtual transaction ID # %x = transaction ID (0 if none) # %q = stop here in non-session # processes # %% = '%' # e.g. '<%u%%%d> ' #log_lock_waits = off # log lock waits >= deadlock_timeout #log_statement = 'none' # none, ddl, mod, all #log_temp_files = -1 # log temporary files equal or larger # than the specified size in kilobytes; # -1 disables, 0 logs all temp files log_timezone = 'PRC' #------------------------------------------------------------------------------ # RUNTIME STATISTICS #------------------------------------------------------------------------------ # - Query/Index Statistics Collector - #track_activities = on #track_counts = on #track_io_timing = off #track_functions = none # none, pl, all #track_activity_query_size = 1024 # (change requires restart) #update_process_title = on #stats_temp_directory = 'pg_stat_tmp' # - Statistics Monitoring - #log_parser_stats = off #log_planner_stats = off #log_executor_stats = off #log_statement_stats = off #------------------------------------------------------------------------------ # AUTOVACUUM PARAMETERS #------------------------------------------------------------------------------ #autovacuum = on # Enable autovacuum subprocess? 'on' # requires track_counts to also be on. #log_autovacuum_min_duration = -1 # -1 disables, 0 logs all actions and # their durations, > 0 logs only # actions running at least this number # of milliseconds. #autovacuum_max_workers = 3 # max number of autovacuum subprocesses # (change requires restart) #autovacuum_naptime = 1min # time between autovacuum runs #autovacuum_vacuum_threshold = 50 # min number of row updates before # vacuum #autovacuum_analyze_threshold = 50 # min number of row updates before # analyze #autovacuum_vacuum_scale_factor = 0.2 # fraction of table size before vacuum #autovacuum_analyze_scale_factor = 0.1 # fraction of table size before analyze #autovacuum_freeze_max_age = 200000000 # maximum XID age before forced vacuum # (change requires restart) #autovacuum_vacuum_cost_delay = 20ms # default vacuum cost delay for # autovacuum, in milliseconds; # -1 means use vacuum_cost_delay #autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for # autovacuum, -1 means use # vacuum_cost_limit #------------------------------------------------------------------------------ # CLIENT CONNECTION DEFAULTS #------------------------------------------------------------------------------ # - Statement Behavior - #search_path = '"$user",public' # schema names #default_tablespace = '' # a tablespace name, '' uses the default #temp_tablespaces = '' # a list of tablespace names, '' uses # only default tablespace #check_function_bodies = on #default_transaction_isolation = 'read committed' #default_transaction_read_only = off #default_transaction_deferrable = off #session_replication_role = 'origin' #statement_timeout = 0 # in milliseconds, 0 is disabled #vacuum_freeze_min_age = 50000000 #vacuum_freeze_table_age = 150000000 #bytea_output = 'hex' # hex, escape #xmlbinary = 'base64' #xmloption = 'content' # - Locale and Formatting - datestyle = 'iso, mdy' #intervalstyle = 'postgres' timezone = 'PRC' #timezone_abbreviations = 'Default' # Select the set of available time zone # abbreviations. Currently, there are # Default # Australia # India # You can create your own file in # share/timezonesets/. #extra_float_digits = 0 # min -15, max 3 #client_encoding = sql_ascii # actually, defaults to database # encoding # These settings are initialized by initdb, but they can be changed. lc_messages = 'C' # locale for system error message # strings lc_monetary = 'C' # locale for monetary formatting lc_numeric = 'C' # locale for number formatting lc_time = 'C' # locale for time formatting # default configuration for text search default_text_search_config = 'pg_catalog.english' # - Other Defaults - #dynamic_library_path = '$libdir' #local_preload_libraries = '' #------------------------------------------------------------------------------ # LOCK MANAGEMENT #------------------------------------------------------------------------------ #deadlock_timeout = 1s #max_locks_per_transaction = 64 # min 10 # (change requires restart) # Note: Each lock table slot uses ~270 bytes of shared memory, and there are # max_locks_per_transaction * (max_connections + max_prepared_transactions) # lock table slots. #max_pred_locks_per_transaction = 64 # min 10 # (change requires restart) #------------------------------------------------------------------------------ # VERSION/PLATFORM COMPATIBILITY #------------------------------------------------------------------------------ # - Previous PostgreSQL Versions - #array_nulls = on #backslash_quote = safe_encoding # on, off, or safe_encoding #default_with_oids = off #escape_string_warning = on #lo_compat_privileges = off #quote_all_identifiers = off #sql_inheritance = on #standard_conforming_strings = on #synchronize_seqscans = on # - Other Platforms and Clients - #transform_null_equals = off #------------------------------------------------------------------------------ # ERROR HANDLING #------------------------------------------------------------------------------ #exit_on_error = off # terminate session on any error? #restart_after_crash = on # reinitialize after backend crash? #------------------------------------------------------------------------------ # CUSTOMIZED OPTIONS #------------------------------------------------------------------------------ # Add settings for extensions here
1.3 此时主从数据库的配置是相同的，所以可以将主库直接备份，然后还原至从库。其实对于从库，配置本身很简单，只是因为考虑到接下来的主从切换麻烦，所以讲主从配置成一样的。
此时可以使用PG自带的pg_basebackup工具，对主机进行远程基础备份。
在从机中执行：pg_basebackup -F p -D $PGDATA -x -v -h db1 -w
将主机的数据库远程备份并恢复到从机中。其中db1是我添加在系统hosts里的，对于不想添加的，可以直接使用Ip地址。其实hosts中的文件就是给出不同IP的别名，方便使用。其他参数请--help.
1.4 备份还原到从机后，需要添加另外一个配置文件：recovery.conf,此时才把主机与从机区分开来。在PGHOME目录下的share文件夹中有实例文件，将之拷贝过来，修改即可。
执行cp /usr/local/pgsql/share/recovery.conf.sample /usr/local/pgsql/data/recovery.conf.
主要配置：
standby_mode = 'on' #开启从机模式
trigger_file = '/usr/local/pgsql/data/pg.trigger'#注意路径是可以自定义的，但是当主机失效，从机变为主机是，为产生该文件，但当重新恢复为从机自己写的shell脚本要删除该文件，注意权限问题。
primary_conninfo = 'host=db1'
1.5 此时可以启动从机的数据库了。此时会报如下错误：
FATAL: data directory "/usr/local/pgsql/data" has group or world access
DETAIL: Permissions should be u=rwx (0700).
所以，此时要修改data的权限为700.修改之后启动，就没问题了。此时查看启动日志：data/pg_log中的日志如下：
LOG: creating missing WAL directory "pg_xlog/archive_status" LOG: entering standby mode LOG: redo starts at 0/4000020 LOG: consistent recovery state reached at 0/40000C8 LOG: database system is ready to accept read only connections LOG: streaming replication successfully connected to primary
说明，此时从机已经开启了从机模式，只读模式等待连接，并且已经连接到主机的数据库。
1.6验证数据同步。
①在主库中创建表，查看从库中是否有同样的数据表即可。
②当然也可以主机中在psql中执行：select * from pg_stat_replication;
pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | state | sent_location | write_locat
ion | flush_location | replay_location | sync_priority | sync_state
-------+----------+----------+------------------+--------------+-----------------+-------------+-------------------------------+-----------+---------------+------------
----+----------------+-----------------+---------------+------------
22877 | 10 | postgres | walreceiver | 192.168.1.50 | | 47967 | 2015-09-18 16:09:13.711784+08 | streaming | 0/5016334 | 0/5016334
| 0/5016334 | 0/5016334 | 1 | sync
③在主机中运行命令：top -c -u postgres
12707 postgres 15 0 4612 1368 1108 S 0.0 0.1 0:00.09 bash
13190 postgres 18 0 4992 1256 1072 T 0.0 0.1 0:00.02 vi pg_hba.conf
17668 postgres 15 0 281m 16m 15m S 0.0 1.6 0:00.03 /usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
17669 postgres 18 0 9124 660 356 S 0.0 0.1 0:00.00 postgres: logger process
17671 postgres 16 0 281m 3164 2808 S 0.0 0.3 0:00.34 postgres: checkpointer process
17672 postgres 15 0 281m 2544 2208 S 0.0 0.2 0:00.01 postgres: writer process
17673 postgres 15 0 281m 840 504 S 0.0 0.1 0:00.00 postgres: wal writer process
17674 postgres 18 0 282m 1680 984 S 0.0 0.2 0:00.00 postgres: autovacuum launcher process
17675 postgres 18 0 9168 688 356 S 0.0 0.1 0:00.00 postgres: archiver process last was 000000010000000000000004
17676 postgres 16 0 9168 796 424 S 0.0 0.1 0:00.03 postgres: stats collector process
22877 postgres 18 0 282m 2176 1360 S 0.0 0.2 0:00.00 postgres: wal sender process postgres 192.168.1.50(47967) streaming 0/5016334
25439 postgres 15 0 2432 1068 816 R 0.0 0.1 0:00.19 top -c -u postgres
④在从机中运行命令：top -c -u postgres
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12446 postgres 15 0 4612 1384 1120 S 0.0 0.1 0:00.08 bash
19711 postgres 15 0 4612 1376 1116 S 0.0 0.1 0:00.02 bash
20040 postgres 15 0 4612 1360 1124 S 0.0 0.1 0:00.01 bash
20152 postgres 15 0 4612 1388 1124 S 0.0 0.1 0:00.05 bash
21809 postgres 18 0 281m 16m 15m S 0.0 1.6 0:00.05 /usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
21810 postgres 22 0 9120 652 352 S 0.0 0.1 0:00.00 postgres: logger process
21811 postgres 15 0 282m 1784 1420 S 0.0 0.2 0:00.00 postgres: startup process recovering 000000010000000000
21812 postgres 16 0 281m 2988 2640 S 0.0 0.3 0:00.00 postgres: checkpointer process
21813 postgres 15 0 281m 2532 2200 S 0.0 0.2 0:00.00 postgres: writer process
21814 postgres 16 0 9164 780 408 S 0.0 0.1 0:00.00 postgres: stats collector process
21815 postgres 15 0 282m 1768 1244 S 0.0 0.2 0:00.28 postgres: wal receiver process streaming 0/50163B8
24569 postgres 15 0 2432 1072 816 R 0.0 0.1 0:00.14 top -c -u postgres
都可以证明已经正常启动。
