Changes between Initial Version and Version 1 of Public/User_Guide/SCR

Timestamp:

Sep 16, 2016, 1:51:24 PM (8 years ago)

Author:

Andreas Galonska

Comment:

—

Public/User_Guide/SCR

@@ +1 @@
+
+== SCR (Scalable Checkpoint Restart) ==
+
+'''Configuration'''
+
+
+SCR can be configured using Environment Variables or via configuration files.
+Environment variables have to be exported in a batch script via 
+
+{{{export SCR_VAR=<value>}}}
+
+while in configuration files they only need to be defined via
+
+{{{SCR_VAR=<value>}}}
+
+'''List of variables'''
+
+
+{{{
+SCR_CONF_FILE = <path to conf file> #let SCR use this configuration file
+SCR_PREFIX = <directory> # should point to the global file system (typically /sdv-work/$USER/your_checkpoints). All Checkpoints are stored there, when flushing.
+SCR_USER_NAME=$USER #mandatory
+SCR_JOB_NAME=$PBS_JOBNAME #mandatory
+SCR_JOB_ID=`echo  $PBS_JOBID | awk -v FS="." '{print $1}'` #mandatory: used to extract the jobid from PBS for identifying jobs
+
+SCR_COPY_TYPE="FILE"|"LOCAL"|"PARTNER"|"BUDDY" 
+#"FILE" instructs SCR to use multiple checkpoint descriptors defined in the configuration file
+#"LOCAL" instructs SCR to use only _1_ node-local checkpointing
+#"PARTNER" instructs SCR using also a partner node to store the checkpoints (SCR intrinsic Buddy-Checkpointing)
+#"BUDDY" instructs to use the SIONlib Buddy-Checkpointing. Further information on this can be retrieved from k.thust@fz-juelich.de or a.galonska@fz-juelich.de
+
+SCR_FLUSH=X # Let SCR flush from node-local directory to global file system every X checkpoints
+SCR_CACHE_BASE=<cache-directory> # Directory to store node-local files, only used when setting SCR_COPY_TYPE="SINGLE" (default=/tmp)
+SCR_CACHE_SIZE=X # Only store X Checkpoints inside the cache directory (default=2)
+SCR_FETCH=<1/0> # enable or disable fetching from global file system during restart.
+SCR_DEBUG=X # use verbosity level X when running with SCR. Higher X => more output!
+}}}
+
+
+'''Configuration File Example'''
+
+{{{
+SCR_FLUSH=1 # flush every checkpoint
+SCR_DEBUG=0 # ne debug output needed
+SCR_MODE=PIO #use node-local parallel I/O with e.g SIONlib or HDF5. Other Option is "DEFAULT", to use task-local serial IO
+SCR_FLUSH_ASYNC=1 #use asynchronous transfer (only available when using STORE TYPE = BEEGFS
+
+
+
+STORE=/mnt/beeond COUNT=10 TYPE=BEEGFS 
+#using the /mnt/beeond as a cache enables asynchronous transfers of CP files to the global FS (synchronous as well)
+#COUNT=X: Store X CPs inside this store
+#TYPE=DEFAULT/BEEGFS defines if this store is a BEEGFS Cache or not
+
+#STORE=/tmp COUNT=10 TYPE=DEFAULT #when using DEFAULT, no beegfs flushing will be available. Only synchronous flushing copying over the files from node-local to global storage.
+
+STORE=/tmp #mandatory: Needed to store metadata for SCR
+
+# Specify the different types of checkpoints for a job
+# 1 is used to store every time a CP to the BEEGFS Cache in this case
+# 2 could be used to create a PARTNER Checkpoint every 4th time.
+# 3 could be used to create a BUDDY Checkpoint with SIONlib every 6th time.
+# times is by means of calling SCR_Need_checkpoint(int *flag) in your code, when flag=1
+# every CKPT descriptor needs an appropiate configured STORE (see above)
+
+CKPT=1 STORE=/mnt/beeond INTERVAL=1 TYPE=SINGLE
+#CKPT=2 STORE=/tmp INTERVAL=4 TYPE=PARTNER
+#CKPT=3 STORE=/tmp INTERVAL=6 TYPE=BUDDY 
+
+}}}
+
+