DBAsupport.com Forums - Powered by vBulletin
Results 1 to 6 of 6

Thread: Raw devices

  1. #1
    Join Date
    Jul 2000
    Posts
    521
    DBAs,

    I'm sure that this is also one of those discussed-to-death topics but still...

    Are there any situations where Raw File Systems are the first (and may be the only) choice for database files ? Is the database size one of the criterion for deciding @ this ? If yes, can a close to a terrabyte size db be a compelling reason to go for RFS and OPS ?

    What can be the other considerations here ? I keep on hearing that the DBA job becomes more difficult in RFS. Is this true ? If yes, in what sense ?

    Does anyone have some kind of performance comparison figures between dbs on RFS and conventional (they call it Cooked) file systems ?

    Any info on this topic please...Thanks
    svk

  2. #2
    Join Date
    Jun 2000
    Location
    Madrid, Spain
    Posts
    7,447
    may be you can have a look at Note 37914.1 and 23037.1 on Metalink

    [Edited by pando on 11-19-2001 at 05:39 PM]

  3. #3
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    Are there any situations where Raw File Systems are the first (and may be the only) choice for database files ?
    Yes, for example with Oracle Parallel Server (Real Application Cluster) you must use raw devices for most files. It is actually only the archivelogs which are cooked.

    Is the database size one of the criterion for deciding @ this ?
    No.

    What can be the other considerations here ? I keep on hearing that the DBA job becomes more difficult in RFS. Is this true ? If yes, in what sense ?
    No really. I use raw partitions. Once you create them, things go back to normal (What's normal :-))

    The major problem you might face is estimating the maximum for the partititions.



  4. #4
    Join Date
    Jan 2001
    Posts
    2,828

    Talking

    Hello

    Please refer Oracle 24X7 tips and techniques by venkat devraj there is a excellent treatise on the subject for a discussion on raw file systems vs cooked file ssytems.

    beware that raw file systems are difficult to manage because you cannot run normal os commands on them.(as there is no file systems)

    With tools like Logical volume manager and the performance improvements in filesystems if you are not using OPS i am against raw file systems

    regards
    Hrishy

  5. #5
    Join Date
    Jun 2001
    Location
    Helsinki. Finland
    Posts
    3,938
    With tools like Logical volume manager and the performance improvements in filesystems if you are not using OPS i am against raw file systems
    Absolutely right. If you don't need them, forget about them.

    There is a myth + debate about online logs being on raw devices. You will see DBAs who will explain you why it is so important that the redologs should be on raw partitions, there are the DBA who say that it really doesn't matter noawdays.

    If you are really interested on the subject read "Why raw log files" at http://www.ixora.com.au/tips/creation/raw_log_files.htm

    or even better read "Why Raw Datafiles"

    http://www.ixora.com.au/tips/creation/raw_datafiles.htm


  6. #6
    Join Date
    Jul 2000
    Posts
    521
    Thanks folks. Its informative.
    svk

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Click Here to Expand Forum to Full Width