RE: High disk capacity dangers

  • From: "Jesse, Rich" <Rich.Jesse@xxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 6 Jun 2006 08:35:50 -0500

It was a few years ago and therefore subject to updating, but I've
typically seen the "80%" Rule.  The idea being that a physical drive
fills from the outer tracks, and the speed of the data bits as they fly
by the heads slows as the inner tracks are approached (think of standing
on the outer edge of a merry-go-round versus being in the middle of it).
Somehow, the generic "80%" was settled on as a filling point past which
the access speed of data on the inner tracks degrades "too much".

The problem I've had with this theory is that the person that came up
with it had apparently never partitioned drives nor used NTFS before.  A
Diskkeeper map of my C: drive shows a fair amount of usage on the lower
portion.  (warning: I *assume* that translates to the inner tracks)  So
even at only 50% full, a good portion of my data may be on the slow part
of the disk.  I don't think I've seen such a tool for traditional
Unix/Linux FSs like ext2/3, xfs, jfs, etc., so I'm not sure how those
FSs fill a disk.

Just my $.02,

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Fred Smith
Sent: Tuesday, June 06, 2006 7:05 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: High disk capacity dangers

Just wanted to run this by everyone here, I have a database on 
HP-UX. Some of my read only tablespaces are on a physical disk that I
at about 99% capacity (it's not going to grow obviously, it's
The new Unix SA is saying that it's unacceptable and dangerous to keep a

disk at 98,99, or 100% capacity. I always thought it could be even at
capacity without any problems.

Is there any reason that anyone knows of as to why a disk should not be
99% or 100% capacity?

Thank you!

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