Grid(Engine_CKPT)                   GE 6.1                   Grid(Engine_CKPT)



NNAAMMEE
       Grid Engine Checkpointing - the Grid Engine checkpointing mechanism and
       checkpointing support

DDEESSCCRRIIPPTTIIOONN
       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 _-_c_k_p_t option of the _q_s_u_b_1() command.  The  argument  to  this
       flag   refers   to  a  checkpointing  environment,  which  defines  the
       attributes of the checkpointing method to be  used  (see  _c_h_e_c_k_p_o_i_n_t_5()
       for  details).   Checkpointing  environments  are setup by the _q_c_o_n_f_1()
       options _-_a_c_k_p_t, _-_d_c_k_p_t, _-_m_c_k_p_t and _-_s_c_k_p_t. The _q_s_u_b_1() option _-_c can be
       used  to overwrite the _-_w_h_e_n 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 --cckkpptt option to _q_s_u_b_1()) to be per-
       mitted to run in such a queue.  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 _q_m_o_d_1() by  the  cluster
          administration  or  a  queue owner if the  x occasion specifier (see
          _q_s_u_b_1() _-_c and _c_h_e_c_k_p_o_i_n_t_5()) was assigned to the job.

       +o  A load average value exceeding the migration threshold as configured
          for the corresponding queues (see _q_u_e_u_e___c_o_n_f_5().)

       +o  Shutdown  of  the  Grid  Engine  execution daemon _s_g_e___e_x_e_c_d_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.  NNoottee::  The  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.


RREESSTTRRIICCTTIIOONNSS
       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.

SSEEEE AALLSSOO
       _s_g_e___i_n_t_r_o_1(,)  _q_c_o_n_f_1(,)  _q_m_o_d_1(,)  _q_s_u_b_1(,) _c_h_e_c_k_p_o_i_n_t_5(,) _G_r_i_d _E_n_g_i_n_e
       _I_n_s_t_a_l_l_a_t_i_o_n _a_n_d _A_d_m_i_n_i_s_t_r_a_t_i_o_n _G_u_i_d_e_, _G_r_i_d _E_n_g_i_n_e _U_s_e_r_'_s _G_u_i_d_e

CCOOPPYYRRIIGGHHTT
       See _s_g_e___i_n_t_r_o_1() for a full statement of rights and permissions.



$Date: 2007/11/06 18:18:12 $           1                     Grid(Engine_CKPT)
