[K12OSN] OT: still have sluggish system

[Eric Harrison]

dahopkins at comcast.net wrote:
> All, this is OT, but an issue that I have to resolve.
> 
> Systems at NCS are still very very very (...) sluggish once more than
> about 10 users log on.  No idea why.  I have noticed that using usb
> devices exacerbates the situation tremendously.  I have posted to
> ltsp and recieved some suggestions that I can try, but ... has anyone
> seen sluggish behavior on their systems with FC5?  df -k hangs,
> rdesktop is unusable for all practical purposes, anything that access
> the filesystem just crawls (e.g. ls -l), or using StarOffice, etc.
> ifconfig shows the NICs with no errors, also, no swap is being used,
> load average though is often past 20. top isn't showing any process
> with more than 3% cpu, most are fractional percentages. But ...
> network traffic is very very high.  I guess it could be a NIC issue,
> but on all my servers across 3 different switches?  Before the
> upgrade to the latest release, things ran spiffy.  With 10 or so
> users, things run spiffy, add 5 or so more, and things crawl.
> 
> Also, I noticed after the upgrade that users cannot connect to one of
> the Win2K terminal servers unless they first connect to the other
> Win2K server. But this is only from one of the upgraded systems, the
> other works fine.
> 
> Anyhow, thanks for reading, and any advice is appreciated.
> 
> Sincerely, Dave Hopkins Newark Charter School
> 


The high bandwidth usage is an obvious candidate. Any idea on what is
chewing up the bandwidth?


I would also check for authentication/authorization issues (I note in
the archives that you use LDAP).

  Double-check that all of the LDAP configs are correct.

  Make sure that nscd is running (/sbin/service nscd status)

  Make sure that DNS is correct (/etc/resolv.conf)


I'd also check the disk sub-system...

  Run "dmesg" and look for SCSI errors

  Run "sar -b" to see the disk I/O usage patterns
  (if you don't have "sar", install it with "yum install sysstat")




-Eric