CONVEX .=-,.....-'-. Checkpoint Restart - ._ -~==- Guide ~- Order No. DSW-350 First Edition November, 1990 CONVEX Computer Corporation Richardson, Texas USA CONVEX Checkpoint Restart Guide Order No. DSW-350 Part No. 710-006530-001 Copyright 1990 CONVEX Computer Corporation. All rights reserved. This document is copyrighted. This document may not, in whole or part, be copied, duplicated, reproduced, translated, electronically stored, or reduced to machine read­ able form without prior written consent from CONVEX Computer Corporation. Although the material contained herein has been carefully reviewed, CONVEX Com­ puter Corporation (CONVEX) does not warrant it to be free of errors or omissions. CONVEX reserves the right to make corrections, updates, revisions or changes to the information contained herein. CONVEX does not warrant the material described herein to be free of patent infringement. Unless provided otherwise in writing with CONVEX Computer Corporation (CONVEX), the program described herein is provided as is without warranty of any kind, either expressed or implied, including, but not limited to the implied warranties of merchantability and fitness for a particular purpose. Some states do not allow the exclusion of implied warranties. The above exclusion may not be applicable to all purchasers because warranty rights can vary from state to state. In no event will CONVEX be liable to anyone for special, collateral, incidental or consequential dam­ ages, including any lost profits or lost savings, arising out of the use or inability to use this program. CONVEX will not be liable even if it has been notified of the possibility of such damage by the purchaser or any third party. ~, CONVEX and the CONVEX logo ("C") are registered trademarks of CONVEX Com- puter Corporation. COVUE is a trademark of CONVEX Computer Corporation. COVUE products con­ sist of COVUEbatch, COVUEbinary, COVUEedt, COVUElib, COVUEnet, and COV­ UEshell. UNIX is a trademark of AT&T Bell Laboratories. Printed in the United States of America Revision Information for CONVEX Checkpoint Restart Guide Edition Document No. Description 1st 710-006530-001 Released with CONVEXOS V9.0 November, 1990. Contents Checkpoint Restart Overview 1-1 What is Checkpoint Restart? ........................................................................... 1-1 Utilities .......................................................................................................... 1-2 Library Routines.......................................................................................... 1-2 Checkpoint Restart and CXbatch .............................................................. 1-2 Limitations ......................................................................................................... 1-3 Perfonnance ........................................... ,..................................................... 1-3 Uncheckpointable Processes ...................................................................... 1-3 Files Used by Checkpointed Process ........................................................ 1-3 pid Conflict .................................................................................................. 1-4 Compatibility ............................................................................................... 1-4 CR and Processes Using the Tape System ............................................... 1-4 Accounting ................................................................................................... 1-5 What Happens During Checkpointing .......................................................... 1-6 Checkpointing Process Hierarchies.......................................................... 1-6 Files, Pipes, and Devices ............................................................................ 1-7 Access Permissions ..................................................................................... 1-7 The Checkpoint File .......................................................................................... 1-9 Checkpoint File Name ................................................................................ 1-9 Default Checkpoint File Name ............................................................ 1-9 Specifying a Checkpoint file Name .................................................... 1-10 Checkpoint File Format.............................................................................. 1-10 Checkpoint File Size ................................................................................... 1-10 What Happens During Restart ....................................................................... 1-12 File Access During Restart......................................................................... 1-12 Restarting on a Different System .............................................................. 1-12 User ID and Group ID of Restarted Processes ........................................ 1-12 Restoring the Target Process uid, gid, and Group Access Lists ..... 1-12 File Permission and Communication Problems after Changed uid or gid ................................................................................................ 1-13 Parent Process ID (ppid) of Target Process .............................................. 1-13 Current Working Directory ........................................................................ 1-13 Restarting Under Share .............................................................................. 1-13 Job Control ................................................................................................... 1-14 Control Terminals ................................................................................. 1-14 Process Groups and Terminal Control............................................... 1-14 Passing Signals Through ...................................................................... 1-15 CONVEX Checkpoint Restart Guide, 1st Edition v· The Checkpoint and Restart Utilities 2-1 The chkpnt Command .......................... ....... ...................... .............. ... ............. 2-1 chkpnt Parameter Summary ..................................................................... 2-1 Using the chkpnt Command ..................................................................... 2-2 Save Open Files ..................................................................................... 2-2 Specify Checkpoint File Name and Checkpoint Directory ............ 2-3 Force Checkpointing ............................................................................ 2-4 Checkpoint in Interactive Mode ......................................................... 2-4 Checkpoint Entire Process Hierarchy ................................................ 2-5 Send Signal to Target ........................................................................... 2-5 Diagnostics ............................................................................................. 2-5 Checkpoint Examples ...................................................................................... 2-7 Shell Command Line Mode ...................................................................... 2-7 Interactive Mode......................................................................................... 2-8 Invoking chkpnt in Interactive Mode ................................................ 2-8 Interactive Mode Commands ............................... ..... ......................... 2-9 Print Information about Processes ..................................................... 2-11 Checkpointing a Process Hierarchy in Interactive Mode ............... 2-12 Creating and Using Checkpoint Log Files ........................................ 2-13 The restart Command ............................................................. ......................... 2-15 restart Parameter Summary ...................................................................... 2-15 Using the restart Command...................................................................... 2-15 Send Signals to Target .......................................................................... 2-16 Restart in Interactive Mode ................................................................. 2-16 Copy Back Files ..................................................................................... 2-16 Force Restart .......................................................................................... 2-17 Wait/Don't Wait................................................................................... 2-17 Diagnostics ............................................................................................. 2-17 Restart Examples .............................................................................................. 2-18 Shell Command Line Mode ...................................................................... 2-18 Interactive Mode ......................................................................................... 2-18 Invoking restart in Interactive Mode ................................................. 2-18 Interactive restart Commands ............................................................ 2-19 Print Information About a Process..................................................... 2-21 Restarting a Process Hierarchy in Interactive Mode ....................... 2-21 Checkpoint Restart Programming Interface 3-1 Checkpoin.t C Function .................................................................................... 3-1 chkpnt() Format and Parameters ............................................................