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Re: Disk performance deteriated to unbearable levels

David Purton wrote:
> Everything takes forever to load (including booting), but then runs ok
> once loaded.

Could DMA be disabled now?  Taking a long time to read initially but
running okay afterward would match that symptom.  Because after the
initial read it should be in filesystem buffer cache.

> My only guess is that it is filesystem related, but I am not sure how to
> confirm this, nor why things would have got to the present situation.
> Currently, the root/system parition is 20GB, with 50% used. /home has
> only 44% used.

That seems like a good amount of free space available for the
filesystem to deal with disk fragmentation.

> Any suggestions?

Since other suggested possible hard drive problems...  What does
smartctl say about the health of your drive?

  smartctl -H /dev/sda

Any selftest failures?  Are you running smartctl selftests?  If not
then please do.  I always run selftests regularly to get feedback
about the drives.  Let me suggest something similar to this in
/etc/smartd.conf so as to have these run automatically.

  # Monitor all attributes, enable automatic online data collection,
  # automatic Attribute autosave, and start a short self-test every day
  # between 2-3am, and a long self test Saturdays between 3-4am.
  # On failure run all installed scripts (to send notification email).
  # Ignore attribute 194 temperature change.
  # Ignore attribute 190 airflow temperature change.
  /dev/sda -a -o on -S on -s (S/../../[1-5]/03|L/../../6/03) -I 194 -I 190 -m root -M exec /usr/share/smartmontools/smartd-runner

This will dump the selftests.  Any failures?

  smartctl -l selftest /dev/sda

If you need to manually run selftests:

  smartctl -t short /dev/sda

If short passes pick a time and run:

  smartctl -t long /dev/sda

You might try using 'hdparm' to produce some data for your disk.  Read
the hdparm documentation first (lots of docs on the web such as this)


and then you might try this on an otherwise idle system.

  # hdparm -tT /dev/sda
  Timing cached reads:   4634 MB in  2.00 seconds = 2320.31 MB/sec
  Timing buffered disk reads: 378 MB in  3.01 seconds = 125.71 MB/sec

Lastly you could benchmark the filesystem (a layer on top of the disk
system) using bonnie/bonnie++.

> Both are ext3

Directly on the disk partition (e.g. /dev/sda5)?  Or on top of LVM?
Or on top of RAID (e.g. /dev/md1)?  Or LVM on RAID?

> I do not want to reinstall if at all possible.

I am always an advocate of upgrades not re-installs.  :-)


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