Re: DBV slow W2K server
- From: "Christo Kutrovsky" <kutrovsky.oracle@xxxxxxxxx>
- To: mln@xxxxxxxxxxxx, Sean.oneill@xxxxxxxxxx
- Date: Wed, 31 May 2006 11:12:35 -0400
Worst thing is Oracle support still asks for or recommends running it.
Seán, I use RMAN's backup validate for this. I am not sure if dbv has
DirectIO on when doing a verify, I am pretty sure it doens't have
async IO.
RMAN has both DirectIO (if supported, and Windoes does support, just
turn it on with filesystemio_options=setall) and asyncIO. Add
parallelism and you have the fastest database verify.
Why would you run it ? I have no idea :) I use it to find corrupted
blocks. It populates v$database_block_corruption which is quite handy.
Especially with the block-recover feature of RMAN.
Oh, and it's also very usefull to do performance benchmarks on sequencial IO.
--
Christo Kutrovsky
Senior Database/System Administrator
The Pythian Group - www.pythian.com
I blog at http://www.pythian.com/blogs/
On 5/30/06, Mogens Nørrgaard <mln@xxxxxxxxxxxx> wrote:
Aaaarrrrgggghhhhhh. DBV used to be the funniest thing around Oracle -
namely when we made fun of the Sybase customers who would run this silly
thing time and again. Oh man, they weren't even allowed to call Sybase
Support unless they had run DBVerify. The catch being that it might take
more than 24 hours to run (it scaled, but not in the cool way, as they
say), and so they had huge problems.... Man, were we laughing about this
and using it massively in Oracle's internal competitive info on Sybase.
Then Oracle did it themselves. Was it in 8.0? And suddenly the
competitive info changed. Unfortunately, it also led to this strange
belief (based on Oracle's documentation) that DBV is good for something.
It pretty much isn't. It's actually faintly dangerous in my opinion.
Why on EARTH would anyone want to run this silly thing? It is a waste of
resources, time and all other things. There might - might - be a few
cases where it could provide useful information, but weigh that against
the costs of running it, the false sense of security it might generate -
and the features and bugs in it that will mis-lead the
not-so-experienced into thinking something horrible is going on in the
blocks - and I can only conclude:
Don't Bother, Vriends.
Mogens
PS: It's taking a very long time because it's doing a lot of IO. So
either stop using DBV or buy more disks.
=?iso-8859-1?Q?O'Neill@xxxxxxxxxxxxx wrote:
>Hi Folks,
>
>Would appreciate some help/guidance with an issue I've noticed with the dbv
utility on Windows 2000 server. I'm using this utility as part of an offline
backup process. For some reason the dbv is now taking over 9 hours to complete.
It used to take about half this time. I've been to Internet to try and track down
if this is a known issue but to no avail. The Oracle manuals have not been much
help either. I've looked at the server and it does not appear to be maxed out by
anything that would cripple the dbv executing.
>
>Regards,
>- Seán O' Neill
>--
>//www.freelists.org/webpage/oracle-l
>
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//www.freelists.org/webpage/oracle-l
--
Christo Kutrovsky
Senior Database/System Administrator
The Pythian Group - www.pythian.com
I blog at http://www.pythian.com/blogs/
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//www.freelists.org/webpage/oracle-l
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