RE: Disk Device Busy (%) - What exactly is this?
- From: "Taylor, Chris David" <ChrisDavid.Taylor@xxxxxxxxxxxxxxx>
- To: "'cichomitiko@xxxxxxxxx'" <cichomitiko@xxxxxxxxx>, 'Guillermo Alan Bort' <cicciuxdba@xxxxxxxxx>
- Date: Mon, 21 Nov 2011 10:29:59 -0600
I don't think that actually 'accurate' though.
There are real IO limits on the following:
1.) LUNS themselves (how many disks in the stripe, RAID levels)
2.) IO Controller Card between the server and the LUN or disk
NOW, the question that 'should be' asked is:
"How does my OS determine the IO capacity of my storage?"
Imagine if the OS does a statistics gathering on the IO subsystem (much like
Oracle does on tables) then it can possibly "know" within a reasonable margin
of error what the expected IO bandwidth is for the storage system (regardless
of whether or not it is a LUN or a DISK).
So, does ANYONE know how the OS (Windows, Linux etc) tries to determine the
maximum IO available across a disk or LUN?
Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
"Quality is never an accident; it is always the result of intelligent effort."
-- John Ruskin (English Writer 1819-1900)
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-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Radoulov, Dimitre
Sent: Monday, November 21, 2011 10:21 AM
To: Guillermo Alan Bort
Cc: oracle-l-freelists
Subject: Re: Disk Device Busy (%) - What exactly is this?
Hi Alan,
yes, this was new to me too. In another mail Grzegorz Goryszewski have just
posted a link to an article by Alex Gorbachev, which seem to confirm that too:
Quoting it:
Traditionally, it's common to assume that the closer to 100% utilization a
device is, the more saturated it is.
This might be true when the system device corresponds to a single physical disk.
However, with devices representing a LUN of a modern storage box, the story
might be completely different.
[...]
Regards
Dimitre
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