Author: Stephen Davies Date: To: hampshire Subject: [Hampshire] System Upgrade Woes
A few months ago supplied a couple of systems to a client that go like
the proverbial sh1t off a hot shovel.
These were a pair of IBM X-series server with 2 Quad Core 3.0Ghz CPU's
32Gb Ram and 1.5TB of SAS & Fibre connected Raid. These were setup with
SUSE SLES 9 but after some application problems, we switched over to
RHEL 4.5.
Now hat these boxes are in production, he wanted to build a cheapo
server for dev & test. So, I upgraded one of his existing servers with
a new Motherboard, CPU, RAM. He had a few SATA Disks that were added to
the config.
Rigt from the start, the system ran like an absolute dog with 2.5 legs
(apologies to Jaqui...)
I looked at the disk setup with 'hdparm' and sure enough, DMA was disabled.
However when I tried to enable DMA it refused ( hdparm -d 1 /deb/hda )
saying that it was not possible to do this.
After some googling on the subject, I found that some people had had
similar problems upgrading from Ubuntu Dapper.
I changed the kernel config line in /boot/grub/menu.lst to look like the
following
Now the system runs much better. The disks are /dev/sda instead of /dev/hda
the hdparm -tT /dev/sda ( /dev/hda) tests show an increase of the
buffered disk reds from 3.309Mb/sec to 71.48MB/sec
So, if you are tempted to upgrade an existing system or build a new one
from bits, watch out. You might encounter the issues I have had here.
The New Motherboard was a Gigabyte one. I have never encountered this
problem with other boards from this manufacturer before. It seems that
its all down to how the SATA/IDE emulation is handled in the bios and
the revision of the SATA Driver (libata) in the O/S used.
I expect that there might be some live distros that fall foul this
malade as well.
