Some rudimentary testing on a laptop here (500Mhz,
512M RAM, typical single disk)
- visiting a single block via 4,000,000 logical IO's
got me approx 35000 gets/sec
- repeated full table scans similar system got me
approx 350 phys reads/sec
After this extensive, thorough and exhaustive
exercise, I can definitely say that memory access
versus disk access (as it pertains to Oracle) is 100
times faster on this machine in single user mode
I think we can generalise this to be the rule for all
servers under all conditions :-)
Connor
- "Freeman, Robert " <Robert_Freeman_at_csx.com>
wrote: > I've heard the disk vs. memory arguments
before, but
> never have seen
> quantifiable data either way... if anyone has any,
> I'd love to see it.
>
> RF
>
> Robert G. Freeman - Oracle8i OCP
> Oracle DBA Technical Lead
> CSX Midtier Database Administration
>
> The Cigarette Smoking Man: Anyone who can appease a
> man's conscience can
> take his freedom away from him.
>
>
>
> -----Original Message-----
> Sent: Monday, March 18, 2002 5:54 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Robert - So THAT is the title of your next book. I'm
> primed to buy it
> already.
> I just recalled a legend, maybe. "Disk is 10,000
> times slower than memory,
> so memory access times are infinitesimal compared to
> disk access". Cary
> Millsap covers this in his Hotsos Clinic. He has run
> tests that prove "ain't
> so". The point is that you can't just use ratios to
> tune Oracle, but need to
> look at wait times.
> Dennis Williams
> DBA
> Lifetouch, Inc.
> dwilliams_at_lifetouch.com
>
>
> -----Original Message-----
> Sent: Monday, March 18, 2002 1:04 PM
> To: Multiple recipients of list ORACLE-L
>
>
> So, does the CoO (Church of Oracle) have an
> infallibility doctrine then???
>
> ... From the Book of Oracle, chapter 5 ...
>
> ...and the DBA did look upon his database, and he
> saw it was good.
> His tablespace datafiles being distributed tither
> and fro, spread amongst
> the
> platters of his disks. And he did complete that
> which was called
> documentation,
> and then he rested from his labors, and drank
> Mountain Dew Code Red...
>
>
> :-)
>
> Robert G. Freeman - Oracle8i OCP
> Oracle DBA Technical Lead
> CSX Midtier Database Administration
>
> The Cigarette Smoking Man: Anyone who can appease a
> man's conscience can
> take his freedom away from him.
>
>
>
> -----Original Message-----
> Sent: Monday, March 18, 2002 12:25 PM
> To: Multiple recipients of list ORACLE-L
>
>
>
> Hey, you're an author!
>
> I expect perfection, grace and infallibility. ;)
>
> Jared
>
> On Monday 18 March 2002 07:33, Freeman, Robert
> wrote:
> > And hey, it was Sunday morning at 0700
> something... what do you
> > expect from me anyways??? :-)))))))
> >
> > RF
> >
> > Robert G. Freeman - Oracle8i OCP
> > Oracle DBA Technical Lead
> > CSX Midtier Database Administration
> >
> > The Cigarette Smoking Man: Anyone who can appease
> a man's conscience can
> > take his freedom away from him.
> >
> >
> >
> > -----Original Message-----
> > Sent: Sunday, March 17, 2002 6:43 PM
> > To: Multiple recipients of list ORACLE-L
> >
> > On Sunday 17 March 2002 07:53, Freeman, Robert
> wrote:
> > > 1. You do not open the database to users until
> AFTER you do a backup
> (hot
> > > or cold, dosen't mater) at point t2.
> >
> > Well, yeah, that was the point. It doesn't have
> to be a cold backup, but
> > since you can't do any work, it may as well be a
> cold backup.
> >
> > Jared
> >
> > > 2. There is a method of recovering a database
> (8i +) after RESETLOGS has
> > > been
> > > issued with archived redo logs. I discussed it
> in my DBA World Tour
> > > backup and
> > > recovery presentation. To do this, you MUST have
> the control file for
> the
> > > database from BEFORE the resetlogs operation,
> and backup of the control
> > > file from AFTER the same operation. I've done
> this about 3 times in
> >
> > testing
> >
> > > and it works fine but it very very picky about
> the control file images.
> > >
> > > RF
> > >
> > > Robert G. Freeman - Oracle8i OCP
> > > Oracle DBA Technical Lead
> > > CSX Midtier Database Administration
> > >
> > > The Cigarette Smoking Man: Anyone who can
> appease a man's conscience can
> > > take his freedom away from him.
> > >
> > >
> > >
> > > -----Original Message-----
> > > Sent: Friday, March 15, 2002 7:28 PM
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > > Hi Jared,
> > >
> > > > > * You *have* to take a COLD backup of the
> database after using
> > > >
> > > > resetlogs.
> > > >
> > > > > (Not required - a Hot backup and archive
> logs is adequate. All hot
> > > >
> > > > backups /
> > > >
> > > > > archive logs prior to that are invalid,
> though...)
> > > >
> > > > Consider the following:
> > > >
> > > > Time:
> > > >
> > > > t0: database restored
> > > > t1: database opened with RESETLOGS
> > > > t2: hot backup started ( database in archive
> log mode )
> > > > t3: users input very important transactions
> > > > t4: database crashes, and must be restored
> > > >
> > > > How will you recover the transactions from
> time t3?
> > >
> > > As long as the online redologs are available,
> this should be no problem.
> > > I have successfully recovered databases where a
> log switch did not occur
> > > and recovery had to use an online redo log. (I
> am assuming that the lost
> > > datafiles will be restored from this hot backup
> fresh off the tapes)
> > >
> > > On the other hand, if the online redolog is
> hosed you have lost the
> > > transactions anyway, _regardless_ of the fact
> that a Cold backup was
> >
>
=== message truncated ===
Connor McDonald
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http://www.oradba.freeserve.co.uk)
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Received on Wed Mar 20 2002 - 03:48:49 CST
