could not locate required checkpoint record

いつものCentOS4.6＋PostgreSQL8.3.1＋VMwarePlayerを2つ使って、スタンバイDBを構築したところ、スタンバイ側が起動しない。。。pg_logにあるログを見てみると、

LOG:  database system was interrupted; last known up at 2008-05-14 10:53:49 JST
LOG:  starting archive recovery
LOG:  restore_command = 'pg_standby -l -d -s 2 -t /tmp/pgsql.trigger /var/lib/pgsql/backups %f %p %r 2>>/var/lib/pgsql/s
tandby.log'
LOG:  restored log file "000000010000000000000001.00000020.backup" from archive
LOG:  restored log file "000000010000000000000001" from archive
LOG:  WAL file is from different system
DETAIL:  WAL file SYSID is 5200054916662099573, pg_control SYSID is 5200044492776461819
LOG:  invalid checkpoint record
PANIC:  could not locate required checkpoint record
HINT:  If you are not restoring from a backup, try removing the file "/var/lib/pgsql/data/backup_label".
LOG:  startup process (PID 7403) was terminated by signal 6: Aborted
LOG:  aborting startup due to startup process failure

なんですか、「invalid checkpoint record」って。。。
で、ログをよく見てみると

HINT:  If you are not restoring from a backup, try removing the file "/var/lib/pgsql/data/backup_label".

とあるので、確認してみると、

$ ls /var/lib/pgsql/data/backup_label
/var/lib/pgsql/data/backup_label
$ cat backup_label
START WAL LOCATION: 0/1000020 (file 000000010000000000000001)
CHECKPOINT LOCATION: 0/1000020
START TIME: 2008-05-14 11:29:33 JST
LABEL: Label
$ 

ベースバックアップを取ったときに作られるファイルでした。で、これを

$ rm /var/lib/pgsql/data/backup_label
$ 

してやると、問題なく起動。あー、びっくりした。