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, > 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 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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