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.

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In comp.unix.solaris Joe D. <newbie_from_newbie@yahoo.com> 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
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