Dell PowerStore 3000X EMC PowerStore Importing External Storage to PowerStore - Page 53

All these network connections must be established before starting the import and they must be working well for import and cancel to be successful. Also, it is highly recommended that the connection from PowerStore to the source array be a high-speed network with redundant connections. Also, both systems should be within a short distance of each other to minimize network latency issues. Import alerts and error codes When an import operation fails, the error message indicates the nature of the problem to help you resolve the issue. If you attempt to recover from a failure and do not succeed, the error messages include a numeric code for reference. This code is provided to help your service provider quickly resolve the issue. In certain types of failures, along with error messages, PowerStore generates import alerts. Two categories of alerts are generated: critical and minor. Critical alerts are generated for situations that require manual intervention and for some reason automatic recovery has failed. For example, the source went down while a background copy from PowerStore was occurring. The import fails because PowerStore is not able to reach the source volume in the SAN path. Also, the subsequent automatic cancel does not fully succeed because the host could not reach the source and the source volume could not restore back to its normal state. To recover, bring the source back up, do any required cleanup, and try the import again. Minor alerts are generated when user intervention is not required but some operation has failed. For example, the import failed because the host did not have the appropriate connections to the destination volume. However, automatic recovery occurred and I/Os were redirected back to the source volume without I/O impact. Resolve the error, and retry the operation. Failures during import Some failures might be intermittent in nature, for example, due to the load of the system or network. Usually, if the import attempt is not successful, the I/Os are not affected and they continue with the source volumes. A simple retry of import suffices for them. Sometimes, the resolution of network or load issues is required before retrying the import. When an import fails, the error message attempts to indicate in simple words to the end user what went wrong without getting too technical. If repeated attempts fail or, if the message is not helping, or both, contact your service provider. Single fault Any single fault in the middle of an import is handled without any impact to host I/Os as described in the following examples: • If during the import, the destination loses the back-end connection with the source array in the SAN path, the import is automatically canceled by the PowerStore import orchestrator. I/Os from the host are redirected back to the source. In most situations, this process occurs without any I/O disruption. However, the import fails and must be retried after you fix the SAN paths from PowerStore to the source array. • If one of the source SPs reboots but the surviving SP can service the source volume, both import and I/Os continue without any impact. Depending on the nature of the fault, the import orchestrator handles them so that there is minimum impact on the host I/Os. In all these cases, error messages, or alerts, or both describe the issue to the user. Based on system load, it is possible that the errors between PowerStore and the source network result in I/O errors to a user application, even when an automatic cancel occurs. For such rare cases, user intervention may be required to restart the I/Os to the source volumes. If the problem persists, contact your service provider for resolution. Source disaster recovery If the source array has a disaster recovery (DR) incident in which it becomes entirely unreachable during import, the following applies: • If a different host is used in the DR site for recovery, then the existing source array-specific DR procedure should work. The importspecific states are only for the primary site array volume. These states have no bearing on the array volume of the secondary or DR sites. • If the same host is used to run the applications when the primary array is impacted in a disaster, then the following applies: ○ When the primary (source) array fails, the import process initiates an automatic cancel operation. Check whether the automatic cancel is successful. Once this operation successfully completes, continue with the source-specific DR recovery procedure. ○ If automatic cancel was not successful, for example, it failed due to network connectivity issues, then additional steps might be required based on the failure. The recovery steps are specific to the error. Contact your service provider for more information about recovery. ○ EqualLogic PS arrays have some limitations which affect DR during import. Contact your service provider for resolution. Fault handling by PowerStore import 53