[Box Backup] Housekeeping hogging the server

Imran Niazi boxbackup@fluffy.co.uk
Sat, 21 Oct 2006 12:54:18 -0700

I can't remember the original message exactly, and I don't know if he is
running Linux?

On Redhat anyway (maybe CentOS & Fedora also), sometimes DMA mode for
harddrives/controller isn't enabled.  (or maybe its never enabled until you
enable it explicitly).  If it is Linux, run hdparm on your harddrive, e.g.
"hdparm /dev/hda". 

This will tell you if dma is enabled or not, as well as multiple sector count
for I/O, IO_support is set to 32bit, and unmaskirq is enabled etc. 

Before you try to reenable them, make sure its not doing any active I/O on the
drive.  To enable them for /dev/hda using hdparm is "hdparm -u1 -c3 -d1 -m16

Sometimes the system will disable some or all of them if it gets a harddrive
error, i.e. bad sector.  So if it fixes the problem and then you check again a
few days later, and they are reset to old values (and you haven't rebooted
since then), then look through your dmesg or /var/log/messages for
kernel/harddrive errors.  

Also if its just a matter of the system not setting the correct values on boot
(i.e. reboot the computer before changing the values, and check the values),
then you will need to set them everytime you reboot or set it in your startup

Warning: There is a chance that this could put the system in a unstable state
(if you have a controller/chipset incompatability, harddrive problems etc). 
so make sure you aren't doing anything important when you do this.  save your
work, etc.  If your system locks up etc., you will have to completely power
down the system for a few seconds atleast.  Also if it does lock up, most
likely you have some type of an incompatability between the OS & hardware.  Or
sometimes set the options seperately in three different commands, instead of
combining it as I did. It shouldn't do any permanent damage as long as you
don't try to modify any other settings other than the ones I mentioned. 
Unless of course you know what you are doing.

Ok, I tried to cover most of the bases, in case someone else runs into this.