Oracle FAQ Your Portal to the Oracle Knowledge Grid

Home -> Community -> Mailing Lists -> Oracle-L -> (Fwd) TAR# 1280667.996:Can NT/Win2k server OS defrag utilities

(Fwd) TAR# 1280667.996:Can NT/Win2k server OS defrag utilities

From: Eric D. Pierce <>
Date: Mon, 12 Mar 2001 11:44:50 -0800
Message-ID: <>

Does anyone else get the impression that Oracle tech support isn't really answering the question about OS fragmentation below??????

I thought it was obvious that moving db files when the db is open is likely to be a bad idea, but can't imagine why defragging at the OS level when the db is closed would be a problem.

eg, I read an Oracle tech support note that describes how to move db files from one NT machine to another. If one can move the files from one machine to another, why can't the db files be reorganized (at the OS level) on the *same* machine?

This seems like an obvious question (and probably a straightforward issue), I don't understand why Oracle tech support is so ambiguous and lacking in explanation/justification for their statements.

If they are so enthusiastic about exp/imp, why wouldn't they be as interested in gaining performance by additionally optimizing disk access at the OS level?

Or maybe I'm wrong and NT/Win2k actually does a really efficient job of laying out large files (Oracle's pre-allocated db file storage) just like Oracle tech support is hinting?


bcc: campus SysAdmn gurus

                            Oracle Worldwide Support
                            Incident Tracking System

      TAR#: 1280667.996                  Reported: 10-MAR-2001 (CUS-3027991)
  Assigned: DATASRVW (CHFREEMA.US)        Updated: 12-MAR-2001 (CHFREEMA.US)
  Severity: Severe Loss of Service (2)
    Status: Soft Close (SCL)
  Platform: MS Windows 2000
   Product: Oracle Server - Enterprise Edition (8.1.7)
     RDBMS: 8.1.7

  Customer: TRUSTEES CALIFORNIA STATE UNIV    Contact: Eric Pierce Phone: 916 278-7586

Can NT/Win2k server OS defrag utilities be *safely* used on the db files?

### Platform and O/S version, including patchset orservice pack level? ### Oracle 8.1.x Micsosoft NT4 server or Windows 2000server.

### What version and patchset level of the database are you running?### 8.1.7.?.?

### Please describe your problem: ###

This is a generic question about behavior of Oracle8i on NT4 server (or Windows2000 server): It is ok to use disk defragmentation utilities (eg, Norton speedisk for NT) on the Oracle 8i db files? An individual on the Oracle-L listserv says that NT defrag utilities will corrupt the db files (he is claiming that the physical placement of the db files at the OS block level is "fragile" from Oracle's perspective). This seems to contradict my experience working with Oracle7.3 on Netware, where it is quite possible to move db files around, and then have Oracle see them in a new location and go on operating normally. We are trying to set up a plan for dbserver tuning/maintenance, and need to know if disk defragging is required and/or advisable for performance and recovery reasons on NT/Windows2000 servers.

Eric D. Pierce
Student Services
CSU, Sacramento
reply by
or phone (916) 278-7586


### What is the impact to your business because of thisproblem? ### could potentially be high, but it is not a current operationalissue

Contact me via : E-mail ->

If your database is open when you are doing the defrag it will corrupt your data every time. With a 3rd party utility when the database is closed would have to be tested to see if it would even work. Make sure that you take a backup before you try this though.

That really doesn't help much, and seems to possibly contradict the conventional wisdom of NT SysAdmns, which is to defrag a file system constantly.
Please comment on the Oracle-l listserv post that started the discussion:
(thanks!!! ep)
|Using a little utility called contig I noticed that the Oracle
| 8.1.6 datafileson my test NT server are quite fragmented, an
| average of 177 fragments perfile, 118 fragments for the OEM
| repository datafile. The poor utilitycouldn't do anything with
| the database files, they are too large perhaps.
|These were created on an empty server, 8i release 2 went on it
| after a defrag,then the OEM. This is on a hard disk with 1.2G of
| free space, none of thedatafiles come close to that.
| Why so many fragments? Oracle created thosefiles in one pass,
| does NT write randomly to disk or what?
| Won't thishave an impact on my NT database's performance?
| Oracle says tablespacefragmentation is not a big deal, but
| fragmentation at the OS level matters.Supposedly that's why NT
| and WndowsXX came with defragmentation tools.
| Is there a registry setting somewhere to tell NT to write
| contiguouslyto disk?


Datafiles, if sized correctly, should never need to be defragged. If you are concerned that there is fragmentation on your oracle file take an export.

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
To REMOVE yourself from this mailing list, send an E-Mail message to: (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Mon Mar 12 2001 - 13:44:50 CST

Original text of this message