Motorola 6806800C47B Manual Do Utilizador
Shared Memory Configuration
API Description
Checkpoint Service Programmer’s Reference (6806800C47B)
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2.3.1
Shared Memory Configuration
NCS3.0 Checkpoint service uses the shared memory for storing the checkpoint replicas.
Checkpoint service will manage the shared memory segments created by it for storing the
checkpoint replicas. The shared memory requirements for storing the checkpoint replica can be
derived from the checkpoint creation attributes supplied at the time of saCkptCheckpointOpen(
) or saCkptCheckpointOpenAsync( ) call using the formula. maxSections *
Checkpoint service will manage the shared memory segments created by it for storing the
checkpoint replicas. The shared memory requirements for storing the checkpoint replica can be
derived from the checkpoint creation attributes supplied at the time of saCkptCheckpointOpen(
) or saCkptCheckpointOpenAsync( ) call using the formula. maxSections *
maxSectionSize
The maximum size of the shared memory segment is limited by the operating system. In most
of the cases, the maximum value is 31MB. This can be found by executing the command: cat
of the cases, the maximum value is 31MB. This can be found by executing the command: cat
/proc/sys/kernel/shmmax
To increase the shared memory size to the desired value, one can use the following command:
echo 134217728 >/proc/sys/kernel/shmmax
echo 134217728 >/proc/sys/kernel/shmmax
The above example command will set the maximum shared memory segment value to 27MB.
2.3.2
Maximum Data Size Per One write or Overwrite
The maximum data size per one write or over write is 40MB. Applications that try to write more
than 40MB data in one saCkptSectionWrite( ) or saCkptSectionOverwrite( ) call
will get the error SA_AIS_ERR_NO_RESOURCES.
than 40MB data in one saCkptSectionWrite( ) or saCkptSectionOverwrite( ) call
will get the error SA_AIS_ERR_NO_RESOURCES.
2.4
Service Dependencies
The internal interfaces of the Checkpoint service are given below:
z
Layered Environment for Accelerated Portability (LEAP) - for Shared Memory: Checkpoint
Service uses LEAP for portability. The service uses the memory manager, timers, encode-
decode utility and handle manager services provided by the LEAP.
Service uses LEAP for portability. The service uses the memory manager, timers, encode-
decode utility and handle manager services provided by the LEAP.
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Message Distribution Service (MDS) - for Messaging: All the interaction between the
different subparts of the Checkpoint service will take place using MDS messaging. The
MDS is also used to register the service up and down events to handle the failure cases.
different subparts of the Checkpoint service will take place using MDS messaging. The
MDS is also used to register the service up and down events to handle the failure cases.
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Distributed Tracing Service (DTSv) - for Logging messages: Checkpoint service uses DTSv
to log debug messages, which are stored in a file and could be used for debugging and to
report informational events.
to log debug messages, which are stored in a file and could be used for debugging and to
report informational events.
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Availability Service (AvSv) - for High Availability: CPD and CPND are modelled as AMF
components.
components.
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Message based Checkpoint Service (MBCSv) - for checkpointing information: CPD uses
the MBCSv to checkpoint the state information with the standby CPD.
the MBCSv to checkpoint the state information with the standby CPD.
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Cluster Membership Service (CLM) - for Node names: CPD uses Cluster membership
service to get the node name for a given node ID. Node names are required to implement
Checkpoint service MIBs.
service to get the node name for a given node ID. Node names are required to implement
Checkpoint service MIBs.
The Checkpoint library libSaCkpt.so depends on functions found in the following library:
libncs_core.so
libncs_core.so