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fwd: 20 Differences Between Oracle on NT and Oracle on Unix

From: Eric D. Pierce <PierceED_at_csus.edu>
Date: Tue, 17 Apr 2001 13:08:29 -0700
Message-ID: <F001.002EB40F.20010417124520@fatcity.com> 







 Doc ID:   Note:45967.1


 Subject:  20 Differences Between Oracle on NT and Oracle on Unix
 Type:     FAQ


 Status:   PUBLISHED


                                       Content Type: 
                                                         TEXT/PLAIN
                                       Creation Date: 
                                                         02-JUL-1997
                                       Last Revision Date: 
                                                         09-APR-2001







 20 DIFFERENCES BETWEEN ORACLE ON WINDOWS NT AND ORACLE ON UNIX






 PURPOSE





 This note enumerates the 20 most obvious differences between
 (Oracle on) Unix and NT.



 SCOPE & APPLICATION





 This note is directed towards dba's and system engineers with
 either a moderate knowledge of (Oracle on) NT or Unix.



 RELATED NOTES





 [NOTE:46001.1] : Oracle and the Windows NT memory architecture
 [NOTE:46053.1] : Windows NT Memory Architecture Overview



    
  
  1.   AVAILABILITY

   



 Windows NT has been existence since 1993. It runs on two processor
 architectures: Intel X86 (needs Pentium) and Digital Alpha AXP.
 The Windows NT operating system is only available from Microsoft.



 UNIX has been in existence since 1972: previous versions did exist,
 but they were written in PDP assembly language, rather than C. UNIX
 runs on most hardware architectures and versions are supplied by 
 many vendors, most notably Sun, HP, IBM, Digital, Sequent, Data
 General, NCR and SCO.




 2. SECURITY

    
 Windows NT 3.5 has been evaluated successfully at U.S. Department
 of Defense C2 security level (TCSEC class C2 rating). A utility on
 the Windows NT Resource kit, C2 Configuration/Security Manager,
 reports the state of compliance of the relevant features, such as
 whether the last username is displayed at logon.



 As of 2000.07.25 NT 4.0 does not have a TCSEC class C2 rating.



 For Microsoft's own statement about this, see:



 http://www.microsoft.com/NTServer/security/exec/feature/c2_security.asp



 Some specialised UNIX variants support the B1 level of security.




 3. USER INTERFACE


 Windows NT has a common graphical user interface across architecture
 types. The interface changed between NT 3.51 and NT 4.0 from
 Windows 3.11 style to Windows 95/98 style.



 Many UNIX versions have an X-Windows type of user interface, the
 appearance varying between flavours. Linux in particular offers a
 number of GUI interfaces, including Windows look-alikes. However,
 most UNIX commands are still character mode terminal based.




 4. NUMBER OF DISK DRIVES


 Windows NT is limited to using drive letters A-Z, though use of raw
 partitions can allow disks to be divided up into smaller sections (see
 question 17).



 UNIX has no built-in limitation on number of disk drives.




 5. BACKGROUND PROCESSING AND BATCH JOBS


 NT only has the AT command. An easier-to-use GUI version may be found
 on the Resource Kit.



 UNIX has more sophisticated job control mechanisms.




 6. RECOMPILATION


 NT applications only require recompiling if moved to a
 different architecture, e.g. Intel to Alpha.



 UNIX applications require recompiling if moved to a different
 platform, e.g. HP to IBM RS/6000. They also need recompiling
 for different UNIX releases on the same platform.




 7. SCALABILITY


 Standard Windows NT currently scales effectively to four CPUs, though
 some manufacturers have recently announced eight-way systems. 



 UNIX scales to at least 64 CPUs.




 8. NUMBER OF SESSIONS


 Windows NT supports only a single interactive GUI session, unless
 Microsoft Terminal Server, RAS or a third-party tool is used.



 UNIX supports hundreds of interactive GUI or character mode
 sessions.




 9. APPLICATION AVAILABILITY


 Several thousand applications are available specifically for Windows NT.
 It can also run many of the thousands of 16-bit Windows applications.
 Third-party products allow some UNIX applications to be run, though the
 greatest interest is the other way, enabling Windows NT applications to
 run under UNIX variants, especially Linux. Some public domain software
 is available for Windows NT.



 There are many thousands of UNIX applications on the market. A large
 amount of public domain software is also available. Emulation software,
 available for many flavours of UNIX, allows many 16-bit Windows
 applications to be run. 



    
  
  1.   FILESYSTEM TYPES AND CAPABILITIES





 Windows NT supports two filesystems - FAT and NTFS. Oracle software and
 datafiles can be installed on either type, with the following provisos:



 Security






 Once a user is connected to an NT server, they must then have
 access to a file to be able to access it.



 NT files can only have a single name (unless using POSIX).
 Files on UNIX can have multiple names via hard or soft links.




    
  
  1.   CLUSTERING





 Windows NT clustering has only become available relatively recently.
 Most of the major hardware vendors support it. Two Oracle products for
 Windows NT clusters are Oracle Parallel Server and Oracle Fail Safe.
 The latter is for two-node clusters, where an instance can only run on
 one node at a given time.



 UNIX clustering has been in existence for several years. Oracle Parallel
 Server has been available on UNIX since early Oracle7 releases. Oracle
 Fail Safe is not available for UNIX.




    
  
  1.   PROCESSES AND THREADS





 Each Oracle background "process" (e.g. LGWR, DBWR, ARCH, etc.), and each
 dedicated server "process" is a thread of the master ORACLE process on
 Windows NT. The multi-threaded architecture is very efficient on Windows
 NT, permitting fast, low-overhead context switches due to all threads
 sharing resources of the master process.



 With Oracle7 and 8.0.x on Windows NT, most Oracle executables and hence
 processes had a two-digit version number appended to the name, to allow
 multiple versions to be installed into the single ORACLE_HOME. With the
 introduction of multiple ORACLE_HOMEs on NT in release 8.0.4, this was
 no longer necessary, and as of 8.1.5 the UNIX style of using just the
 name has been adopted. 



 With multiple Oracle instances running on Windows NT, there will be
 one ORACLE process per instance, each with multiple component threads.



 Each Oracle background process exists as a separate process on
 UNIX.





    
  
  1.   THE MULTI-THREADED SERVER (MTS)





 Despite Oracle's inherently multi-threaded architecture on NT
 (see previous point), the multi-threaded server option of the
 RDBMS was not part of the Oracle7 port on Windows NT. Thus, each
 client connection was a dedicated connection, with each connected
 session getting a dedicated server thread within the ORACLE7x process. 
 However, Oracle8 on Windows NT fully supports MTS.



 UNIX Oracle7 ports have supported MTS since early Oracle7 releases.




    
  
  1.   SERVICES AND DAEMONS





 NT Services are similar to UNIX daemons, permitting a program to
 run independent of a user logon session.



 Oracle registers each instance as a service to allow them to be
 started independent of a user logging on (e.g. instance started on
 machine boot). By default, services run as the SYSTEM user in NT.
 SYSTEM is not a user which can create a logon session - it is
 specifically for running system-orientated services. Oracle server
 processes on UNIX keep running even if no interactive users are
 logged on.




    
  
  1.   SETTING ORACLE_HOME





 Oracle on Windows NT utilises variables in the registry similarly to     
 the way Oracle on UNIX utilises shell environment variables.



 ORACLE_HOME and ORACLE_SID are variables defined in the NT Registry.
 The Oracle Installer and Oracle Instance Manager define variables in
 the Registry as well as registering the Oracle instance as a service.
 The Registry can be edited manually via the REGEDT32 utility, to change
 the values of variables, but this should be undertaken with care.



 Release 8.0.4 of Oracle was the first release on Windows NT that
 allowed support for more than one Oracle home. This was a large
 step forward in providing comparable installation capabilities to 
 Oracle on UNIX. If using release 8.0.4 or higher, the Oracle Home
 Selector utility, not the ORACLE_HOME environment variable, should
 be used to specify the setting of Oracle home.



 Oracle on UNIX requires ORACLE_HOME and ORACLE_SID to be set in system 
 or user login scripts. UNIX has always supported multiple ORACLE_HOMEs.




    
  
  1.   PERFORMANCE MONITORING





 Oracle on Windows NT is integrated with the NT Event Viewer and
 Performance Monitor utilities.



 The Event Viewer utility is how an NT administrator views system
 alert messages on NT. Oracle has integrated with Event Viewer such 
 that Oracle startup/shutdown messages and the OS audit trail (if
 you configure OS auditing in Oracle) appear there. Performance
 Monitor is the NT equivalent of the UNIX sar or vmstat command,
 providing detailed resource utilisation data for all processes
 running on the system.



 Oracle has integrated with Performance Monitor such that you can
 view utilisation of operating system and Oracle resources (e.g. file
 write bytes per second - only those related to Oracle, library cache
 hit ratios, etc.). The Oracle Performance Monitor entry in the
 Start Menu > Programs > Oracle for Windows NT starts the standard
 NT Performance Monitor utility but feeds it Oracle-specific data.



 Although multiple instances of Oracle can be run on Windows NT, the
 NT Performance Monitor and Event Viewer utilities can only "see" one
 Oracle instance at a time. For details of how to edit the relevant
 registry variables, see [NOTE:46875.1] or the Getting Started Guide
 for Oracle on Windows NT.



 Oracle on UNIX provides no performance utilities for use at operating
 system level. Utilities such as sar or vmstat must be used to monitor
 Oracle background or shadow processes. These do not provide a graphical
 interface. More sophisticated third-party tools are available on UNIX.




    
  
  1.   RAW PARTITIONS





 Windows NT supports raw (unbuffered) disk partitions, where Oracle can
 store data, log or control files. Each raw partition can be assigned a
 drive letter, but will not be formatted with a filesystem.



 Similarly to UNIX, each raw NT partition will be mapped to a single
 Oracle data, log or control file. Where NT differs from UNIX is
 the naming convention for these files. When referencing a raw
 partition in any Oracle SQL command, the syntax looks like this:



 DATAFILE '\\.\f:' SIZE 49M REUSE



 where f: is the drive letter assigned to the raw partition, referred to
 here as a logical raw file. Windows NT and Oracle also support physical
 raw files, with device names of the form:



 \\.\PhysicalDriveN



 where N is the number of the physical drive, as seen in Disk Administrator.
 Physical raw files would need to be used on a system with more drives than
 available drive letters for the desired number of raw partitions.



 The OCOPY utility can be used to copy data to and from raw partitions,
 in a similar way to the UNIX dd command. Backup of a raw partition must
 be to a filesystem. The NT Backup utility can then be used to copy the
 backup to tape as required.



 On both Windows NT and UNIX, raw partitions must be used for the shared
 data files in a Parallel Server environment, where special Oracle
 utilities are provided for manipulating them.




    
  
  1.   CONNECT INTERNAL





 A password is required to CONNECT INTERNAL for Oracle on Windows NT.
 The database password is defined during installation and by default
 is stored in a hidden password file called "PWD<SID>.ora" in the
 DATABASE directory under "ORACLE_HOME".



 There is a Windows NT equivalent to the UNIX dba group. The NT username
 used to install Oracle8i Enterprise Edition is automatically added to a 
 Windows NT local group called ORA_DBA, which receives SYSDBA privilege.
 This obviates the need for a password when issuing commands such as
 CONNECT INTERNAL and CONNECT / AS SYSDBA. On the same principle, an 
 ORA_OPER group can be created for database operators, and finer-grained 
 security is possible by use of the "ORA_<SID>_DBA" and "ORA_<SID>_OPER"
 groups.




    
  
  1.   HOT BACKUPS





 Oracle on Windows NT supports hot backups using the same backup
 strategy as it on UNIX, i.e. put the tablespaces into backup mode and
 copy the files to the backup location. Then bring the tablespaces out
 of backup mode. By definition, this can all be done while the database
 is up and in use (though it is best to choose a quiet time, when there
 are few transactions).



 The Windows NT feature to be aware of is that NT Backup does not allow
 files in use to be copied, so you must use the OCOPY utility that
 Oracle provides to copy the open database files to another disk location.
 Since OCOPY cannot copy files directly to tape, you will then need to use 
 NT Backup or a similar utility to copy the files to tape, as required.




 20. RELINKING


 Oracle on Windows NT is supplied as a set of executables and dynamic link
 libraries (DLLs). Relinking by the user is not possible on Windows NT, but
 executable images can be modified using the ORASTACK utility, to change
 the size of the stack used by the threads of the Oracle server process.
 This can be useful to avoid running out of virtual memory when using a
 very large SGA, or with thousands of connections. It is recommended that
 this tool should be used under the guidance of Oracle Support.



 On UNIX, object files and archive libraries are linked to generate the
 Oracle executables, and relinking is necessary after operations such as 
 installation of a patch or Net8 protocol adapter.




 REFERENCES


 Oracle for Windows NT - Getting Started




                                                        Oracle Support Services


 .




  Copyright (c) 1995,2000 Oracle Corporation. All Rights Reserved. Legal
  Notices and Terms of Use.




---end---


-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Eric D. Pierce
  INET: PierceED_at_csus.edu

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Received on Tue Apr 17 2001 - 15:08:29 CDT












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