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Disk I/O errors happen more often than you might think. This means that BSR replication Features of passthrough policy

bsr must be able to flexibly cope with these disk I/O errors from the replication side as well, given that it depends on the lower disk layer, and errors in the SCSI layer can occur at any point in time. The DETACH respond to errors occurring in the lower SCSI storage layer.

The detach policy, which has been provided as a disk failure policy, is was a policy that unilaterally stops replication in which replication was unilaterally stopped at a certain specific point in time , which is disadvantageous from a service operation point of view, as it perspective. This method is difficult to recover after the fact and is also disadvantageous from a disadvantageous in terms of continuing service operation continuation point of view. We devised the PASTHROUGH policy in response to these issues and set it as the default policy for BSR. When .

The pass-through policy records OOS for the corresponding block when an I/O error occurs , the passthrough policy records an OOS for the block and forwards and delivers the failed I/O result to the filesystem. If the filesystem then rewrites the failed block to clear the OOS, this will encourage the filesystem to overcome the transient disk-file system. At this time, if the file system resolves OOS by rewriting the block where the error occurred, this will lead the file system to overcome the temporary disk layer error on its own. Even if the filesystem does not completely resolve the OOS due to its behavior, some of the OOS cannot be completely resolved depending on the operating characteristics of the file system, some remaining OOS can be resolved by resynchronization, such as by retrying the connection. In other words, the resynchronizing through connection retries, etc.

The pass-through policy encourages guides the FS to resolve the error block by itself error blocks on its own or through synchronization, and essentially guarantees basically ensures that the service will continue to operate service operation continues even if there is a are disk I/O problemproblems.