为什么 Barman 的备份数据库无法结束（待定）？

做过操作：

barman cron
barman receive-wal --create-slot pg
barman receive-wal pg
barman switch-wal --force --archive pg

然后运行检查和备份命令：

-bash-4.2$ barman check pg
Server pg:
    PostgreSQL: OK
    is_superuser: OK
    PostgreSQL streaming: OK
    wal_level: OK
    replication slot: OK
    directories: OK
    retention policy settings: OK
    backup maximum age: OK (no last_backup_maximum_age provided)
    compression settings: OK
    failed backups: OK (there are 0 failed backups)
    minimum redundancy requirements: OK (have 0 backups, expected at least 0)
    pg_basebackup: OK
    pg_basebackup compatible: OK
    pg_basebackup supports tablespaces mapping: OK
    systemid coherence: OK (no system Id stored on disk)
    pg_receivexlog: OK
    pg_receivexlog compatible: OK
    receive-wal running: OK
    archive_mode: OK
    archive_command: OK
    archiver errors: OK
-bash-4.2$ barman backup pg
Starting backup using postgres method for server pg in /var/lib/barman/pg/base/20200305T124531
Backup start at LSN: 0/5100A7B8 (000000010000000000000051, 0000A7B8)
Starting backup copy via pg_basebackup for 20200305T124531
(pending)

很长一段时间后它无法完成。检查/var/lib/barman/pg/base/20200305T124531/路径：

• 备份信息
• 数据

在data中，似乎已经复制了来自 pg 服务器的数据。请参阅中的内容backup.info：

backup_label=None
begin_offset=42936
begin_time=2020-03-05 12:45:31.020705+09:00
begin_wal=000000010000000000000051
begin_xlog=0/5100A7B8
config_file=/var/lib/pgsql/10/data/postgresql.conf
copy_stats=None
deduplicated_size=None
end_offset=None
end_time=None
end_wal=None
end_xlog=None
error=None
hba_file=/var/lib/pgsql/10/data/pg_hba.conf
ident_file=/var/lib/pgsql/10/data/pg_ident.conf
included_files=None
mode=postgres
pgdata=/var/lib/pgsql/10/data
server_name=pg
size=None
status=STARTED
systemid=6795775088862271947
tablespaces=None
timeline=1
version=100012
xlog_segment_size=16777216

检查过程，得到：

barman    5661  0.0  0.2 258560 19204 ?        Ss   12:45   0:00 /usr/bin/python2 /bin/barman -c /etc/barman.conf -q receive-wal pg
barman    5671  0.0  0.0 176384  3416 ?        S    12:45   0:00 /usr/pgsql-10/bin/pg_receivewal --dbname=dbname=replication host=pg options=-cdatestyle=iso replication=true user=streaming_barman application_name=barman_receive_wal --verbose --no-loop --no-password --directory=/var/lib/barman/pg/streaming --slot=barman
postgres  5675  0.0  0.0 397052  3844 ?        Ss   12:45   0:00 postgres: wal sender process streaming_barman 127.0.0.1(41570) streaming 0/534365C8
barman    5745  0.0  0.2 258564 19080 pts/0    S+   12:45   0:00 /usr/bin/python2 /bin/barman backup pg
barman    5751  0.0  0.0 176132  3316 pts/0    S+   12:45   0:00 /bin/pg_basebackup --dbname=dbname=replication host=pg options=-cdatestyle=iso replication=true user=streaming_barman application_name=barman_streaming_backup -v --no-password --pgdata=/var/lib/barman/pg/base/20200305T124531/data --no-slot --wal-method=none
postgres  5752  0.0  0.0 396724  7980 ?        Ss   12:45   0:00 postgres: wal sender process streaming_barman 127.0.0.1(41618) sending backup "pg_basebackup base backup"

为什么不能完成？status=STARTED未更新完成状态。