[Sblim-devel] discussion point : How to handle mass operations ?!?

[Heidi N. <HEI...@de...>]

Hi ,

the goal of this mail is to start a discussion about how
to handle mass operations . It is not always the best
solution to avoid them .

At the moment I'm running in such a mass problem with
the instrumentation of "Filesystems & Volume Management"
and I'm not sure how to solve the forced crashes .


PROBLEM DESCRIPTION

- affected module  :   sblim-fsvol-0.6.1   ( tar.gz  )
                       FSVOL_0_6_1         ( CVS tag )
- affected part    :   the instrumentation of the Logical
                       Volume Manager for Linux (LVM)

- affected class   :   LVM_PVExtent
Each instance of the class LVM_PVExtent represents one
physical extent in the Linux Logical Volume Manager (LVM) .

- provider code    :

   * com/ibm/wbem/linux/device/LVM_PVExtent.java :
     calling the NPI - uninteresting in the problem
     environment

   * LVM_PVExtent.c :

     1 step : enumeration of all physical volumes
              -> 6 physical volumes

     2 step : for each instance of the physical volume
              all physical extents are collected in a list
              -> ~ 4000 = sum of all physical extents
              ! this happens in functions of the tool
                library CimFsVMgmt.c whithout any problems !

     3 step : for each entry in the list of physical
              extents one instance of LVM_PVExtent is
              created ... no - should be created

This enumeration of all instances of the class LVM_PVExtent
brings on the problem how to handle this mass operation
and avoid crashes .


Now one discussion point can be why it seems to be
necessary to do such a "maybe useless" operation . It is,
from a systems management application view, really necessary
to get all the physical extents of one system to have a look
in the way they are connected to their corresponding logical
extents and the logical volume ? What might be a case where
this granularity becomes important ( Standard value fo a
physical extent is 4096 kB !!! ) .
Or shall there be other ways to offer detailed informations .

An other discussion point can be, how to solve such problems
whithout avoiding enumerations with a mass result . I' sure
that there are other environments where it is not possible
to strike out operations that have a mass result .


Now follow some possible solutions as discussion basics .

POSSIBLE SOLUTIONS

* increase the memory allocation size for the Java Virtual
Machine ???

* take this granularity out of the schema
( delete LVM_PVExtent ) ???

* more suggestions ???




Thanks for your attention ... Heidi




Mfg / Regards

Heidi Neumann

IBM Laboratory Boeblingen - Germany - Dept. 3243
LTC  - -  Linux Technology Center -- 7UFA
                  Systems Management

Phone : ++49 (0) 7031 / 16 - 3193
Schönaicher Str. 220, 71032 Böblingen

        hei...@de...
--- try sametime to contact me ---

http://w3.opensource.ibm.com/projects/ibmcimom/
http://oss.software.ibm.com/developerworks/projects/sblim/