可能很多朋友都遇到过这样的情况,在UNIX/Linux上定期清理Oracle日志文件夹时可能删除到仍被后台进程open着的trace文件,即某些后台进程一直持有着这些”被已经误删了的“打开文件的描述符(fd),这种情况下文件系统上该文件实际占用的空间是不会被释放的,这就造成使用df命令查看文件系统剩余空间和用du命令查看文件夹空间使用量时数值不一致的问题。此外因为是后台进程持有这些打开文件描述符,所以我们无法像kill服务进程一样来解决该问题(部分后台进程是可以kill的,不建议这样做)。oradebug是sqlplus中威力强大的debug命令,我们可以通过该命令发起多种trace/dump,其中也包括了close_trace事件;close_trace事件可以让指定进程关闭其正持有的trace文件。
下面我们就来演示下相关操作:
[maclean@rh2 ~]$ ps -ef|grep ora_|grep -v grep maclean 7281 1 0 16:35 ? 00:00:00 ora_pmon_PROD maclean 7283 1 0 16:35 ? 00:00:00 ora_psp0_PROD maclean 7285 1 0 16:35 ? 00:00:00 ora_mman_PROD maclean 7287 1 0 16:35 ? 00:00:00 ora_dbw0_PROD maclean 7289 1 0 16:35 ? 00:00:00 ora_lgwr_PROD maclean 7291 1 0 16:35 ? 00:00:00 ora_ckpt_PROD maclean 7293 1 0 16:35 ? 00:00:00 ora_smon_PROD maclean 7295 1 0 16:35 ? 00:00:00 ora_reco_PROD maclean 7297 1 0 16:35 ? 00:00:00 ora_cjq0_PROD maclean 7299 1 0 16:35 ? 00:00:00 ora_mmon_PROD maclean 7301 1 0 16:35 ? 00:00:00 ora_mmnl_PROD maclean 7303 1 0 16:35 ? 00:00:00 ora_d000_PROD maclean 7305 1 0 16:35 ? 00:00:00 ora_s000_PROD maclean 7313 1 0 16:35 ? 00:00:00 ora_qmnc_PROD maclean 7430 1 0 16:35 ? 00:00:00 ora_q000_PROD maclean 7438 1 0 16:36 ? 00:00:00 ora_q001_PROD /* lgwr是著名的Oracle后台进程,在这个启动的实例中其系统进程号为7289*/ [maclean@rh2 ~]$ ls -l /proc/7289/fd /* linux上的proc文件系统可以很方便我们探测进程信息*/ total 0 lr-x------ 1 maclean oinstall 64 Jul 26 16:38 0 -> /dev/null lr-x------ 1 maclean oinstall 64 Jul 26 16:38 1 -> /dev/null lr-x------ 1 maclean oinstall 64 Jul 26 16:38 10 -> /dev/zero lr-x------ 1 maclean oinstall 64 Jul 26 16:38 11 -> /dev/zero lr-x------ 1 maclean oinstall 64 Jul 26 16:38 12 -> /s01/rac10g/rdbms/mesg/oraus.msb lrwx------ 1 maclean oinstall 64 Jul 26 16:38 13 -> /s01/rac10g/dbs/hc_PROD.dat lrwx------ 1 maclean oinstall 64 Jul 26 16:38 14 -> /s01/rac10g/dbs/lkPROD lrwx------ 1 maclean oinstall 64 Jul 26 16:38 15 -> /s01/rac10g/oradata/PROD/controlfile/o1_mf_64q6xphj_.ctl lrwx------ 1 maclean oinstall 64 Jul 26 16:38 16 -> /s01/rac10g/flash_recovery_area/PROD/controlfile/o1_mf_64q6xpms_.ctl lrwx------ 1 maclean oinstall 64 Jul 26 16:38 17 -> /s01/rac10g/oradata/PROD/onlinelog/o1_mf_1_64q6xrsr_.log lrwx------ 1 maclean oinstall 64 Jul 26 16:38 18 -> /s01/rac10g/flash_recovery_area/PROD/onlinelog/o1_mf_1_64q6xsoy_.log lrwx------ 1 maclean oinstall 64 Jul 26 16:38 19 -> /s01/rac10g/oradata/PROD/onlinelog/o1_mf_2_64q6xths_.log l-wx------ 1 maclean oinstall 64 Jul 26 16:38 2 -> /s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc lrwx------ 1 maclean oinstall 64 Jul 26 16:38 20 -> /s01/rac10g/flash_recovery_area/PROD/onlinelog/o1_mf_2_64q6xv9o_.log lrwx------ 1 maclean oinstall 64 Jul 26 16:38 21 -> /s01/rac10g/oradata/PROD/onlinelog/o1_mf_3_64q6xw1b_.log lrwx------ 1 maclean oinstall 64 Jul 26 16:38 22 -> /s01/rac10g/flash_recovery_area/PROD/onlinelog/o1_mf_3_64q6xwv0_.log lrwx------ 1 maclean oinstall 64 Jul 26 16:38 23 -> /s01/rac10g/oradata/PROD/datafile/o1_mf_system_64q6wd5j_.dbf lrwx------ 1 maclean oinstall 64 Jul 26 16:38 24 -> /s01/rac10g/oradata/PROD/datafile/o1_mf_undotbs1_64q6wd7f_.dbf lrwx------ 1 maclean oinstall 64 Jul 26 16:38 25 -> /s01/rac10g/oradata/PROD/datafile/o1_mf_sysaux_64q6wd5m_.dbf lrwx------ 1 maclean oinstall 64 Jul 26 16:38 26 -> /s01/rac10g/oradata/PROD/datafile/o1_mf_users_64q6wd89_.dbf lrwx------ 1 maclean oinstall 64 Jul 26 16:38 27 -> /s01/rac10g/oradata/PROD/datafile/o1_mf_temp_64q6xyox_.tmp lr-x------ 1 maclean oinstall 64 Jul 26 16:38 28 -> /s01/rac10g/rdbms/mesg/oraus.msb lr-x------ 1 maclean oinstall 64 Jul 26 16:38 3 -> /dev/null lr-x------ 1 maclean oinstall 64 Jul 26 16:38 4 -> /dev/null l-wx------ 1 maclean oinstall 64 Jul 26 16:38 5 -> /s01/rac10g/admin/PROD/udump/prod_ora_7279.trc l-wx------ 1 maclean oinstall 64 Jul 26 16:38 6 -> /s01/rac10g/admin/PROD/bdump/alert_PROD.log lrwx------ 1 maclean oinstall 64 Jul 26 16:38 7 -> /s01/rac10g/dbs/lkinstPROD (deleted) lrwx------ 1 maclean oinstall 64 Jul 26 16:38 8 -> /s01/rac10g/dbs/hc_PROD.dat l-wx------ 1 maclean oinstall 64 Jul 26 16:38 9 -> /s01/rac10g/admin/PROD/bdump/alert_PROD.log /*可以看到lgwr进程相关trace文件为/s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc,对应打开文件描述符为2*/ [maclean@rh2 ~]$ ls -lh /s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc -rw-r----- 1 maclean oinstall 1.7M Jul 26 16:37 /s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc [maclean@rh2 ~]$ rm -f /s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc /*尝试删除该trace文件*/ [maclean@rh2 ~]$ ls -l /proc/7289/fd|grep lgwr l-wx------ 1 maclean oinstall 64 Jul 26 16:38 2 -> /s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc (deleted) /*文件已处在deleted状态,但lgwr进程仍持有该文件相关的文件描述符,这个时候该文件占有的空间并不会被释放*/ [maclean@rh2 ~]$ lsof|grep lgwr oracle 7289 maclean 2w REG 8,2 1702391 3867134 /s01/rac10g/admin/PROD/bdump/prod_lgwr_7289.trc (deleted) [maclean@rh2 ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.5.0 - Production on Mon Jul 26 17:03:04 2010 Copyright (c) 1982, 2010, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> oradebug setospid 7289; Oracle pid: 6, Unix process pid: 7289, image: oracle@rh2 (LGWR) SQL> oradebug flush; /*写出trace buffer内容到trace文件*/ Statement processed. SQL> oradebug close_trace; Statement processed. /*close_trace能够释放指定Oracle进程正打开着的文件,To close the current trace file use*/ SQL> host [maclean@rh2 ~]$ lsof|grep lgwr [maclean@rh2 ~]$ ls -l /proc/7289/fd/|grep lgwr [maclean@rh2 ~]$ /* 从进程相关的fd文件夹中查找不到原来的trace文件;close_trace命令成功释放了该文件,并回收了磁盘空间。*/
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