Results 1 to 5 of 5
  1. #1
    Join Date
    Jun 2001
    Location
    The Netherlands
    Posts
    38

    Unanswered: ASE 12.0 raw partition/regular filesystem

    Hi,

    We are currently running ASE 12.0 on a Sun E3000 server with the database on raw partitions. As we are moving to new hardware soon I was wondering if we still need raw partitions or if we might as well use regular file systems.

    Could anyone please advise me.

    Thanks,

    Ben

    PS: we are moving to Sun V880 with Solaris 8.

  2. #2
    Join Date
    Jan 2002
    Posts
    28
    Hi


    Response time for read operations is generally better for devices
    stored on UNIX operating system files as compared to devices
    stored on raw partitions. Data from device files can benefit from
    the UNIX file system cache as well as the Adaptive Server cache,
    and more reads may take place without requiring physical disk
    access.

    The raw partion is more secured than the file systems. theirfore you can use raw partion for yr production server and file systems for developement server.


    I think it will be helpful to you.


  3. #3
    Join Date
    Feb 2002
    Location
    S.E. London
    Posts
    5
    Hi,

    We use Unix file systems on all our post 12.0 Production servers,
    we have not experienced performance issues. It gives a great
    deal more flexibility in terms of moving or copying server to other machines and removes reliance on Unix sa's to administer raw devices.

    Make sure you turn dsync off for production systems to ensure data
    integrity, which means writes will suffer but reads are still buffered.

    However this is a big topic with a lot of arguments on both sides. I have heard best performance is achieved if you have Veritas file systems, but this costs.


    Declan

  4. #4
    Join Date
    Jun 2001
    Location
    The Netherlands
    Posts
    38
    Thanks the both of you for your reply. It's very usefull to me.
    Performance won't be that much of an issue since we are moving to a MUCH faster system... I'm only looking at ease of administration (backup and recovery!) .

    One of the thing with the combination Sybase flat file I hear people talking about is the caching of Sybase not working properly together with OS caching resulting in database corruption in case of a system crash. Is this solved by turning dsync off?

    Ben

  5. #5
    Join Date
    Mar 2001
    Location
    Lexington, KY
    Posts
    606
    Ben, that is correct. DSYNC will avoid the write-cache (which could lead to the OS telling ASE something was written and then a crash which would wipe out the cache'd data) and provide better data integrity. Note you lose performance since writing to a buffer is of course much faster than requiring synch'ed data.

    We were on 11.9.2 for Linux for around 6 months with OS files (11.9.2 did not have the dsync flag so all were buffered) and encountered no data loss. We have since moved to 12.5 for linux and turned Dsync ON 'just in case' and did notice a performance hit.

    From what I understand, at least in Linux, filesystem files do not support async I/O which raw devices do. The next Linux patch (12.5.0.1) is slated to have Async I/O capability on the 2.4 kernels. I think once that is out, there will be no advantage to having RAW vs. File System + Dsync.
    Thanks,

    Matt

Posting Permissions

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