Motorola 6806800C47B ユーザーズマニュアル
Checkpoint Service Programmer’s Reference (6806800C47B)
API Description
Time-out Arguments for Checkpoint Service APIs
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Creating extra replicas on the system manager node for non-collated checkpoints is an
overhead. The advantage of a non-collocated checkpoint is that replica will be created in two
places, no matter from how many nodes it is opened.
overhead. The advantage of a non-collocated checkpoint is that replica will be created in two
places, no matter from how many nodes it is opened.
2.2.2
Time-out Arguments for Checkpoint Service APIs
For all synchronous API calls, the application will provide the “timeout” argument. The
application will consider invocation of the particular API failed in case it did not complete the call
by the specified time. CPSv requires that the value passed in the timeout argument is greater
than 100000000 nano seconds (100 milliseconds).
application will consider invocation of the particular API failed in case it did not complete the call
by the specified time. CPSv requires that the value passed in the timeout argument is greater
than 100000000 nano seconds (100 milliseconds).
2.2.3
Cancellation of Pending Callbacks
According to the SAF-AIS-CKPT-B.01.01 specification, whenever a checkpoint is closed, all the
pending callbacks corresponding to this checkpoint should be cancelled. In CPSv,
implementation does cancel the pending callbacks related to closed checkpoints. However, the
selection object already raised and related to cancelled pending callbacks, will not be cleared
or reset. Due to this, saCkptDispatch API may return without invoking callback routine.
pending callbacks corresponding to this checkpoint should be cancelled. In CPSv,
implementation does cancel the pending callbacks related to closed checkpoints. However, the
selection object already raised and related to cancelled pending callbacks, will not be cleared
or reset. Due to this, saCkptDispatch API may return without invoking callback routine.
2.2.4
Maximum Number of Replicas Per Node
CPSv applications can create upto 1,000 replicas per node at a given instance. This includes
the replicas created by CPSv for non-collocated checkpoints as per the “replica creation policy.”
the replicas created by CPSv for non-collocated checkpoints as per the “replica creation policy.”
In the case of collocated checkpoints, CPSv returns SA_AIS_ERR_NO_RESOURCES if an
application attempts to create a new checkpoint and the current number of replicas on the local
node is already the maximum that CPSv can support per node.
application attempts to create a new checkpoint and the current number of replicas on the local
node is already the maximum that CPSv can support per node.
In the case of non-collocated checkpoints, CPSv returns an SA_AIS_ERR_NO_RESOURCES
if the number of checkpoint replicas on the node on which CPSv decides to create a replica is
already the maximum that CPSv can support per node. In all other cases, the checkpoint open
does not return an error but the replicas will not be created on the backup nodes as decided by
the “replica creation policy”.
if the number of checkpoint replicas on the node on which CPSv decides to create a replica is
already the maximum that CPSv can support per node. In all other cases, the checkpoint open
does not return an error but the replicas will not be created on the backup nodes as decided by
the “replica creation policy”.
2.2.5
Handling of SA_AIS_ERR_TRY_AGAIN
If the Checkpoint service API returns SA_AIS_ERR_TRY_AGAIN, the application should
attempt the API call only after a couple of milliseconds. The suggested wait time is 3 seconds
and the number of retries are 12.
attempt the API call only after a couple of milliseconds. The suggested wait time is 3 seconds
and the number of retries are 12.
Note that the Checkpoint write,overwrite, and read operations may sometime return
SA_AIS_ERR_TRY_AGAIN if called simultaneously. This is to avoid any inconsistencies in the
checkpoint database.
SA_AIS_ERR_TRY_AGAIN if called simultaneously. This is to avoid any inconsistencies in the
checkpoint database.
2.3
Configuration
This section describes how the Checkpoint service is preconfigured regarding shared memory
and the maximum write data size.
and the maximum write data size.