Does Savecore cause a reboot? - SUN

This is a discussion on Does Savecore cause a reboot? - SUN ; Hi all; One of our 280R servers runninc Solaris 2.8 crashed the other evening following a memory upgrade. The reboot did not generate a dump in the directory indicated by dumpadm, which IS configured properly. After we correctec the memory ...

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Thread: Does Savecore cause a reboot?

  1. Does Savecore cause a reboot?

    Hi all;

    One of our 280R servers runninc Solaris 2.8 crashed the other evening
    following a memory upgrade. The reboot did not generate a dump in the
    directory indicated by dumpadm, which IS configured properly. After we
    correctec the memory issue (put the old stuff back) and brought up the
    server, I checked the /var/crash/ directory, and there were indeed
    vmunix, bounds, and core files there so I thought no more about it at
    the time.

    Now when I'm going to look at these files, I notice that these were
    from an earlier crash, and there were in fact none from the night of
    the memory error, even though I saw messages indicating the dump was
    being written to the dump device. D'oh!

    I'd like to attempt to pull a dump from the device using savecore. In
    reading the man page, I notice that it runs following a reboot, and
    upon startup, if there has been a dump taken, will write it out to the
    directory spec'ed by dumpadm, and then write a reboot message to the
    log. I'm concerned with the verbiage in the -L option of savecore:

    -L Save a crash dump of the live running Solaris
    system, without actually rebooting or altering
    the system in any way. This option forces
    savecore to save a live snapshot of the system to
    the dump device, and then immediately to retrieve
    the data and to write it out to a new set of
    crash dump files in the specified directory. Live
    system crash dumps may only be performed if you
    have configured your system to have a dedicated
    dump device using dumpadm(1M).

    Call me paranoid, but I want to make sure that the savecrash command
    will not CAUSE the server to reboot, merely pull the dump information
    from the dump device (in my case, swap, which may be overwritten by
    now, anyway). Can someone ease my angst and indicate one way or t'other
    for certain? Is this the proper command, and if not, is there another?

    I would simply issue the savecore command with no options, since I wish
    to pull the info from the current dump device. If I run out of space
    in my crash directory, I'd redirect at that time.


    Thanks as always...

    Joe D.


  2. Re: Does Savecore cause a reboot?

    In comp.unix.solaris Joe D. wrote:
    > I'd like to attempt to pull a dump from the device using savecore. In
    > reading the man page, I notice that it runs following a reboot, and
    > upon startup, if there has been a dump taken, will write it out to the
    > directory spec'ed by dumpadm, and then write a reboot message to the
    > log. I'm concerned with the verbiage in the -L option of savecore:


    > -L Save a crash dump of the live running Solaris
    > system, without actually rebooting or altering
    > the system in any way. This option forces
    > savecore to save a live snapshot of the system to
    > the dump device, and then immediately to retrieve
    > the data and to write it out to a new set of
    > crash dump files in the specified directory. Live
    > system crash dumps may only be performed if you
    > have configured your system to have a dedicated
    > dump device using dumpadm(1M).


    You don't want that.

    Just do a 'savecore .' to try to read and write the files in the current
    directory. It'll work or it won't (if the dump repository has been
    overwriten, the signature will be invalid and you'll get no data).

    -L dumps the *running* system, overwriting what may be any older dump in
    your dump device.

    > Call me paranoid, but I want to make sure that the savecrash command
    > will not CAUSE the server to reboot, merely pull the dump information
    > from the dump device (in my case, swap, which may be overwritten by
    > now, anyway). Can someone ease my angst and indicate one way or t'other
    > for certain? Is this the proper command, and if not, is there
    > another?


    You can't do -L on a system unless you have a dedicated dump device (not
    shared with swap), otherwise you'd overwrite in-use pages... bad.

    But no, it's not supposed to panic the system, just grab the pages while
    it's running. As it says above, "without actually rebooting or altering
    the system in any way."

    > I would simply issue the savecore command with no options, since I wish
    > to pull the info from the current dump device. If I run out of space
    > in my crash directory, I'd redirect at that time.


    Correct.

    --
    Darren Dunham ddunham@taos.com
    Senior Technical Consultant TAOS http://www.taos.com/
    Got some Dr Pepper? San Francisco, CA bay area
    < This line left intentionally blank to confuse you. >

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