Grid(Engine_CKPT)                   GE 6.0                   Grid(Engine_CKPT)



[1mNAME[0m
       Grid Engine Checkpointing - the Grid Engine checkpointing mechanism and
       checkpointing support

[1mDESCRIPTION[0m
       Grid Engine supports two levels of checkpointing: the user level and  a
       operating  system  provided transparent level. User level checkpointing
       refers to applications, which do their  own  checkpointing  by  writing
       restart  files  at  certain  times or algorithmic steps and by properly
       processing these restart files when restarted.

       Transparent checkpointing has to be provided by  the  operating  system
       and  is  usually  integrated in the operating system kernel. An example
       for a kernel integrated checkpointing facility is the Hibernator  pack-
       age from Softway for SGI IRIX platforms.

       Checkpointing  jobs  need to be identified to the Grid Engine system by
       using the [4m-ckpt[24m option of the [4mqsub[24m(1) command.  The  argument  to  this
       flag refers to a so called checkpointing environment, which defines the
       attributes of the checkpointing method to be  used  (see  [4mcheckpoint[24m(5)
       for  details).   Checkpointing  environments  are setup by the [4mqconf[24m(1)
       options [4m-ackpt[24m, [4m-dckpt[24m, [4m-mckpt[24m and [4m-sckpt[24m. The [4mqsub[24m(1) option [4m-c[24m can be
       used  to  overwrite the [4mwhen[24m attribute for the referenced checkpointing
       environment.

       If a queue is of the type CHECKPOINTING, jobs need to have  the  check-
       pointing attribute flagged (see the [1m-ckpt [22moption to [4mqsub[24m(1)) to be per-
       mitted to run in such a queue. As opposed to the behavior  for  regular
       batch  jobs, checkpointing jobs are aborted under conditions, for which
       batch or interactive jobs are suspended or even stay unaffected.  These
       conditions are:

       +o  Explicit  suspension  of the queue or job via [4mqmod[24m(1) by the cluster
          administration or a queue owner if the  [4mx[24m  occasion  specifier  (see
          [4mqsub[24m(1) [4m-c[24m and [4mcheckpoint[24m(5)) was assigned to the job.

       +o  A load average value exceeding the migration threshold as configured
          for the corresponding queues (see [4mqueue_conf[24m(5)).

       +o  Shutdown of the Grid  Engine  execution  daemon  [4msge_execd[24m(8)  being
          responsible for the checkpointing job.

       After  abortion, the jobs will migrate to other queues unless they were
       submitted to one specific queue  by  an  explicit  user  request.   The
       migration  of  jobs leads to a dynamic load balancing.  [1mNote: [22mThe abor-
       tion of checkpointed jobs will free all resources (memory, swap  space)
       which  the  job occupies at that time. This is opposed to the situation
       for suspended regular jobs, which still cover swap space.


[1mRESTRICTIONS[0m
       When a job migrates to a queue on another machine at present  no  files
       are  transferred  automatically  to  that  machine. This means that all
       files which are used throughout the entire job including restart files,
       executables and scratch files must be visible or transferred explicitly
       (e.g. at the beginning of the job script).

       There are also some practical limitations regarding use of  disk  space
       for  transparently  checkpointing  jobs. Checkpoints of a transparently
       checkpointed application are usually stored in  a  checkpoint  file  or
       directory  by  the operating system. The file or directory contains all
       the text, data, and stack space for the process, along with some  addi-
       tional control information. This means jobs which use a very large vir-
       tual address space will generate very large checkpoint files. Also  the
       workstations  on  which  the jobs will actually execute may have little
       free disk space. Thus it is not always possible to transfer a transpar-
       ent  checkpointing  job to a machine, even though that machine is idle.
       Since large virtual memory jobs must wait for a machine  that  is  both
       idle,  and  has  a  sufficient amount of free disk space, such jobs may
       suffer long turnaround times.

[1mSEE ALSO[0m
       [4msge_intro[24m(1), [4mqconf[24m(1), [4mqmod[24m(1), [4mqsub[24m(1),  [4mcheckpoint[24m(5),  [4mGrid[24m  [4mEngine[0m
       [4mInstallation[24m [4mand[24m [4mAdministration[24m [4mGuide,[24m [4mGrid[24m [4mEngine[24m [4mUser's[24m [4mGuide[0m

[1mCOPYRIGHT[0m
       See [4msge_intro[24m(1) for a full statement of rights and permissions.



$Date: 2004/04/19 10:52:02 $           1                     Grid(Engine_CKPT)
