I think you may have missed my sarcasm - I've been on the anti-cache hit ratio bandwagon for a long time...
Cheers Connor --- DENNIS WILLIAMS <[EMAIL PROTECTED]> wrote: > Connor - Cary Millsap presented the results of 10 > trace files in a Hotsos > seminar I attended. The ratio ranged from a high of > 108.57 down to a low of > 0.79. The point is that the ratio is nowhere near > the oft-quoted 10,000. > This means that logical I/Os are not insignificant. > Even if physical I/O > were eliminated (all blocks cached, 100% cache hit > ratio), response time > would not drop to zero. This is why the emphasis in > tuning is shifting from > simple ratios to examining wait times. If the most > significant wait time is > physical I/O, then changing that will improve > overall performance. But if > the most significant wait time lies in another area, > then you may make > significant improvements in physical I/O and still > not improve overall > performance. I certainly wouldn't claim to be an > Oracle tuning expert, but I > believe that the new ideas on tuning that are > emerging provide a significant > step forward in making Oracle tuning more of a > logical process than a > collection of rules of thumb. > Dennis Williams > DBA > Lifetouch, Inc. > [EMAIL PROTECTED] > > > -----Original Message----- > Sent: Wednesday, March 20, 2002 3:49 AM > To: Multiple recipients of list ORACLE-L > > > Some rudimentary testing on a laptop here (500Mhz, > 512M RAM, typical single disk) > > a) visiting a single block via 4,000,000 logical > IO's > got me approx 35000 gets/sec > > b) 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 " <[EMAIL PROTECTED]> > 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. > > [EMAIL PROTECTED] > > > > > > -----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, > === message truncated === ===== Connor McDonald http://www.oracledba.co.uk (mirrored at http://www.oradba.freeserve.co.uk) "Some days you're the pigeon, some days you're the statue" __________________________________________________ Do You Yahoo!? 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