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Full Discussion: Disk performance problem on login
Operating Systems Linux Red Hat Disk performance problem on login Post 302455372 by dangral on Tuesday 21st of September 2010 11:35:34 AM
Old 09-21-2010
Disk performance problem on login
Running CentOS 5.5:
Quote:
Linux mythbox 2.6.18-194.11.3.el5 #1 SMP Mon Aug 30 16:23:24 EDT 2010 i686 i686 i386 GNU/Linux
I've come across a relatively recent problem, where in the last 2 months or so, the root disk goes to 99% utilization for about 20 seconds when a user logs in. This occurs whether a user logs in locally or via ssh. I have tried using lsof to track down the process that is pegging the disk, but no results are returned until the disk thrashing is over, and I don't get any useful results. So I'm looking for a way to proactively narrow down the problem. Here is some more info:
Quote:

# mount
/dev/hdb3 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/hdb1 on /boot type ext3 (rw)
/dev/hda on /videos type xfs (rw,allocsize=256m,logbufs=4)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
Quote:
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/hdb3 23412640 18685492 3518660 85% /
/dev/hdb1 101086 48046 47821 51% /boot
/dev/hda 312440128 222170800 90269328 72% /videos
tmpfs 386724 0 386724 0% /dev/shm
 

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LEARN ABOUT SUSE

blogd

BLOGD(8)						       The SuSE boot concept							  BLOGD(8)

NAME

       blogd - boot logging on /dev/console

SYNOPSIS

       /sbin/blogd [/dev/realtty]

DESCRIPTION

       Without	argument blogd determines the real underlying character device of /dev/console.  blogd spawns a pty/tty pair to reconnect the cur-
       rent /dev/console with the slave of the pty/tty pair. During writing information from this slave to the real character device a ring buffer
       is used to hold the information for writing it to an existing logging file.

       To  fetch  the  real  tty  of /dev/console the program showconsole(8) can be used. This has the advantage that blogd will not hold the real
       character device of /dev/console as its controlling tty (would hangup any running getty on that character device).

SIGNALS

       blogd knows a few signal to contol its behavior.

       SIGQUIT, SIGINT, and SIGTERM
	      will cause blogd tries to write out the ring buffer and to exit.

       SIGIO  says blogd that now it is able to write on /var/log/boot.msg which means that the file system is mounted read/write and  the  kernel
	      messages are written to that file.

       SIGSYS says blogd that it should stop writing to disk but continue to repeat messages to the old devices of the system console.

BUGS

       blogd  needs  a	mounted  /proc	and  /dev/pts  file  system  and tries to set the controlling tty to stdin if the real character device of
       /dev/console is not given.  After reading /proc blogd tries to restore the status of the controlling tty to avoid problems with getty  pro-
       cesses.	This can fail because blogd forks to run in the background as a daemon.

FILES

       /proc/<pid of blogd>/stat
	      the stat file of the blogd process.

       /dev/console
	      the system console.

       /var/log/boot.msg
	      logging file which is created by klogd(8) or dmesg(8).

SEE ALSO

       showconsole(8), syslogd(8), klogd(8), dmesg(8), proc(5).

COPYRIGHT

       2000 Werner Fink, 2000 SuSE GmbH Nuernberg, Germany.

AUTHOR

       Werner Fink <werner@suse.de>

3rd Berkeley Distribution					   Nov 10, 2000 							  BLOGD(8)
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