top command on hp-ux
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Thread: top command on hp-ux

  1. #1
    Join Date
    Jul 2002
    Posts
    335

    top command on hp-ux

    Ok have a hp-ux server with allegedly 8Gb of memory.I do a topand the memory bit comes back:

    Memory: 5711504K (2178356K) real, 9770932K (4077104K) virtual, 28528K free Page# 1/18

    I'm not sysadmin, and I don't understand unix all that well.

    We're running three databases off this box:

    database 1 total SGA = 5072 Mb
    database 2 total SGA = 368 Mb
    database 3 total SGA = 224 Mb

    Databases 2 and 3 are slow, there's a lot of waits on latches coming free.

    So yes there's a memory issue, but how do I find out the amount of memory on the box, Grid reports 8GB, but whats the difference between virtual and real? I thought virtual was when the system starts swapping out etc.

    Basic and stupid question maybe, but after some help.

  2. #2
    Join Date
    Aug 2001
    Location
    chennai,bangalore
    Posts
    840
    Hi,
    Real memory is the memory from RAM(Random access memory) while virtual memory is the amount of space allocated on the system hard disk.

    When ever a process runs our of memory from RAM, it will swap(start) to use the virtual memory. If there is too much swaping then your application on the server will perform slowly.

    Hope your got the difference.

    regards
    anandkl
    anandkl

  3. #3
    Join Date
    Sep 2002
    Location
    England
    Posts
    7,331

    Re: top command on hp-ux

    Originally posted by bazza


    So yes there's a memory issue, but how do I find out the amount of memory on the box, Grid reports 8GB, but whats the difference between virtual and real? I thought virtual was when the system starts swapping out etc.

    Basic and stupid question maybe, but after some help.
    dmesg | grep Phy
    cat syslog | grep Phy

  4. #4
    Join Date
    Jul 2002
    Posts
    335
    Hi,

    thanks for the help.

    Anandkl, yep, that was pretty much my understanding.

    Davey, unfortunately I can't access the syslog.

    After the system consumed all the swap space yesterday(eek), the sysadmin guys added more swap space, but knowing this would not cure the performance issue, I dropped the SGA on datbase 1 by 1Gb, and now databases 2 & 3 are noticeably quicker. No doubt due to the fact the SGA's are no longer running off the swap space. Database1 is also fine, the sga was seemingly oversized.

    But back to my original question, if Grid reports back 8Gb of memory, and the sysadmin guys swear the box has 8Gb of RAM, why do I see in top this figure of 5.7Gb of 'real' memory?

    Is top accurate?

    Bazza

  5. #5
    Join Date
    Jul 2002
    Posts
    335
    anybody?

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