Re: HP-UX Direct vs Buffered I/O

From: LookingForStuff (ccc_at_caraudio.com)
Date: 07/16/05

  • Next message: Pavel Pokorny: "HP-UX 10.20 and tape drive?" 
    Date: Sat, 16 Jul 2005 01:26:57 -0400

    Hi Matt:

    Why not just use raw logical volume instead of vxfs? That way you will
    bypass fs cache.

    Vince
    <mccmx@hotmail.com> wrote in message
    news:1121440226.216536.307710@g43g2000cwa.googlegroups.com...
    > Oracle 9.2.0.4 EE on HP-UX 11i
    >
    > I have a question relating to HP-UX file I/O:
    >
    > As far as I am aware HP-UX is capable of Direct I/O (i.e. bypassing the
    > Unix buffer cache) when using VXFS and the following mount parameter:
    >
    > convosync=direct
    >
    > This parameter is not used in the mount options in /etc/fstab so I am
    > assuming that I am double buffering on I/O operations.
    >
    > However is there any way of 'proving' that a particular operation is
    > going via the OS cache or not. If I tusc/truss the process I will just
    > see pread() calls which may or may not turn into an OS cache hit.
    >
    > Matt
    >

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