背景
centos7 在某一段时间监控报警磁盘使用率达99%，由于监控属于概要形式信息，没有快照信息的监控（能发现某进程的I/O，CPU消耗情况），所以需要在服务器上去定时执行统计命令获取快照信息。
需要通过iostat -dx -k去查看avgqu-sz、await、svctm、%util；
sar -u查看%iowait、%user；
pidstat -d 查看进程I/O读写的快照信息
步骤
- 生成统计信息文件
cat>/tmp/at_task.sh<
pidstat -d 2 >/tmp/pidstat_\`date +%F_%T\`.log 2>& 1 &
sar -u 2 >/tmp/sar_\`date +%F_%T\`.log 2>& 1 &
while [ 1 ];do echo -n \`date +%T\` >>/tmp/iostat_\`date +%F\` 2>& 1 && iostat -dx -k 1 1 >>/tmp/iostat_\`date +%F\` 2>& 1; sleep 2; done &
EOF在while循环中使用iostat的原因是要输出
date +%T时间，不然只有数据，没有时间信息也没有什么用
- 使用at 命令定时执行
at 15:14 today -f /tmp/at_task.sh出现错误
Can't open /var/run/atd.pid to signal atd. No atd running?
重启atd服务
service atd restart
重新开启at定时任务
at 15:14 today -f /tmp/at_task.sh
job 2 at Wed Mar 13 15:14:00 2019
得到如下快照信息
iostat
15:13:35Linux 3.10.0-862.14.4.el7.x86_64 (ip-xxxxx) 03/13/2019 _x86_64_ (4 CPU)
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
vda 0.12 0.07 17.31 19.41 580.79 90.52 36.57 0.09 2.39 4.42 0.57 0.72 2.63
scd0 0.00 0.00 0.00 0.00 0.00 0.00 6.00 0.00 0.28 0.28 0.00 0.25 0.00sar
03:14:00 PM CPU %user %nice %system %iowait %steal %idle
03:14:02 PM all 0.25 0.00 0.38 0.00 0.00 99.37
03:14:04 PM all 1.25 0.13 0.63 0.00 0.00 97.99
03:14:06 PM all 0.25 0.13 0.50 0.00 0.00 99.12
03:14:08 PM all 0.50 0.00 0.50 0.63 0.00 98.37pidstat
03:14:00 PM UID PID kB_rd/s kB_wr/s kB_ccwr/s Command
03:14:02 PM 5700 9089 0.00 6.00 0.00 uxxx
03:14:02 PM 5700 9140 0.00 6.00 0.00 uxxx
03:14:02 PM 5700 9292 0.00 10.00 0.00 uxxx
03:14:02 PM 0 18084 0.00 2.00 0.00 bashkill 掉收集信息的命令
ps -ef | egrep 'iostat|sar|pidstat|while' | grep -v grep | awk '{print $2}' | xargs -l kill但ps -ef | egrep 命令没有获取到while循环的pid，不kill掉该while循环，就会一直对/tmp/iostat_2019-03-13写数据-_-
通过lsof 没有定位到打开文件的进程
lsof /tmp/iostat_2019-03-13
[root@ip-10-186-60-117 ~]#
[root@ip-10-186-60-117 ~]#通过lsof 可以定位到打开mysql-error.log的进程
lsof /opt/mysql/data/5690/mysql-error.log
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
mysqld 12858 actiontech-universe 1w REG 253,1 6345 20083533 /opt/mysql/data/5690/mysql-error.log
mysqld 12858 actiontech-universe 2w REG 253,1 6345 20083533 /opt/mysql/data/5690/mysql-error.log可见，某进程只有一只持有某文件的inode，才可以通过lsof查看文件在被那些进程使用
获取写文件的进程号
安装sysemtap
yum -y install systemtap
SystemTap 是对 Linux 内核监控和跟踪的工具
利用systemtap中的inodewatch.stp工具来查找写文件的进程号
得到文件的inode
stat -c '%i' /tmp/iostat_2019-03-13
4210339获取文件所在设备的major，minor
ls -al /dev/vda1
brw-rw---- 1 root disk 253, 1 Jan 30 13:57 /dev/vda1得到写文件的pid
stap /usr/share/systemtap/examples/io/inodewatch.stp 253 1 4210339
Checking "/lib/modules/3.10.0-862.14.4.el7.x86_64/build/.config" failed with error: No such file or directory
Incorrect version or missing kernel-devel package, use: yum install kernel-devel-3.10.0-862.14.4.el7.x86_64根据系统内核版本在kernel-devel rpm build for : Scientific Linux 7网站上下载相应的kernal-devel包
wget ftp://ftp.pbone.net/mirror/ftp.scientificlinux.org/linux/scientific/7.2/x86_64/updates/security/kernel-devel-3.10.0-862.14.4.el7.x86_64.rpm
rpm -ivh kernel-devel-3.10.0-862.14.4.el7.x86_64.rpm再次执行stap
stap /usr/share/systemtap/examples/io/inodewatch.stp 253 1 4210339
......
Missing separate debuginfos, use: debuginfo-install kernel-3.10.0-862.14.4.el7.x86_64
Pass 2: analysis failed. [man error::pass2]
Number of similar error messages suppressed: 2.
安装debuginfo kernal
debuginfo-install kernel-3.10.0-862.14.4.el7.x86_64
Verifying : kernel-debuginfo-common-x86_64-3.10.0-862.14.4.el7.x86_64 1/3
Verifying : yum-plugin-auto-update-debug-info-1.1.31-50.el7.noarch 2/3
Verifying : kernel-debuginfo-3.10.0-862.14.4.el7.x86_64 3/3
Installed:
kernel-debuginfo.x86_64 0:3.10.0-862.14.4.el7
yum-plugin-auto-update-debug-info.noarch 0:1.1.31-50.el7
Dependency Installed:
kernel-debuginfo-common-x86_64.x86_64 0:3.10.0-862.14.4.el7再次执行stap
stap /usr/share/systemtap/examples/io/inodewatch.stp 253 1 4210339
ERROR: module version mismatch (#1 SMP Tue Sep 25 14:32:52 CDT 2018 vs #1 SMP Wed Sep 26 15:12:11 UTC 2018), release 3.10.0-862.14.4.el7.x86_64
WARNING: /usr/bin/staprun exited with status: 1添加 -v查看详细报错
stap -v /usr/share/systemtap/examples/io/inodewatch.stp 253 1 4210339
Pass 1: parsed user script and 471 library scripts using 240276virt/41896res/3368shr/38600data kb, in 300usr/20sys/320real ms.
Pass 2: analyzed script: 2 probes, 12 functions, 8 embeds, 0 globals using 399436virt/196284res/4744shr/197760data kb, in 1540usr/560sys/2106real ms.
Pass 3: using cached /root/.systemtap/cache/f5/stap_f5c0cd780e8a2cac973c9e3ee69fba0c_7030.c
Pass 4: using cached /root/.systemtap/cache/f5/stap_f5c0cd780e8a2cac973c9e3ee69fba0c_7030.ko
Pass 5: starting run.
ERROR: module version mismatch (#1 SMP Tue Sep 25 14:32:52 CDT 2018 vs #1 SMP Wed Sep 26 15:12:11 UTC 2018), release 3.10.0-862.14.4.el7.x86_64
WARNING: /usr/bin/staprun exited with status: 1
Pass 5: run completed in 0usr/10sys/38real ms.
Pass 5: run failed. [man error::pass5]修改
vim /usr/src/kernels/3.10.0-862.14.4.el7.x86_64/include/generated/compile.h
#define UTS_VERSION "#1 SMP Tue Sep 25 14:32:52 CDT 2018"
改为
#define UTS_VERSION "#1 SMP Wed Sep 26 15:12:11 UTC 2018"
rm -rf /root/.systemtap/cache/f5/stap_f5c0cd780e8a2cac973c9e3ee69fba0c_7030*再次执行
stap /usr/share/systemtap/examples/io/inodewatch.stp 253 1 4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4671) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4677) vfs_write 0xfd00001/4210339
iostat(4683) vfs_write 0xfd00001/4210339
............可见已经得到了写/tmp/iostat_date +%F 文件的进程号，但进程号一直在打印出来，因为后台进程iostat -dx -m 的在while循环中的，每隔sleep 2s 后就会执行一次iostat 产生新的pid。
那要怎样才能让iostat -dx -m 停止写/tmp/iostat_date +%F 文件了？除了重启大法好 $_$
rm -rf 也不能终止后台的while iostat进程写文件，删除了文件后，while循环又会生成新的文件
rm -rf /tmp/iostat_2019-03-1*
stat /tmp/iostat_2019-03-1*
File: ‘/tmp/iostat_2019-03-13’
Size: 146700 Blocks: 512 IO Block: 4096 regular file
Device: fd01h/64769d Inode: 4210339 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Access: 2019-03-14 16:07:26.211888899 +0800
Modify: 2019-03-14 16:18:17.854019793 +0800
Change: 2019-03-14 16:18:17.854019793 +0800正确做法
cat>/tmp/iostat.sh<
while [ 1 ];do echo -n \`date +%T\` >>/tmp/iostat_\`date +%F\` 2>& 1 && iostat -dx -m 1 1 >>/tmp/iostat_\`date +%F\` 2>& 1; sleep 2; done &
EOF
at now + 1 minute today
bash /tmp/iostat.sh
#这样就能方便的获取到进程号pid了
ps -ef | grep iostat
root 8593 1 0 16:16 pts/2 00:00:00 bash /tmp/iostat.sh
