Asset ID:	1-75-1002793.1
Update Date:	2010-03-28
Keywords:

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Solution Type  Troubleshooting Sure

Solution  1002793.1 :   Sun StorageTek[TM] 5000 Series NAS Arrays: Analyzing Replication (Mirroring) Failures  


PreviouslyPublishedAs
203817

Description
Description

Symptoms

- nmir: Mirror vol /xxxx is cracked
- nmir: Mirror link on /xxxx is broken
- nmir: Sync error
- nmir: Watchdog expired on host ...
- nmir: Mirror link to <hostname> [<IP address>] is down!
- nbd: Dropping connection with ...
- nbd: Remote disk io error

Purpose/Scope:

The purpose of this document is to assist a user in resolving failures associated with NAS Replication (Mirroring).

Steps to Follow
Please validate that each troubleshooting step below is true for your environment. The steps will provide instructions or a link to a document, for validating the step and taking corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution. Please do not skip a step.
Step 1 - Verify active license(s) on all systems involved in replication.

Two servers are required for mirroring. The servers can be any model, and they can be different models from one another. Note: Both servers MUST have the same version of the operating system installed.

To activate the File Replicator system option requires the purchase of a license for both the 'active server' (source) and the 'mirror server' (target).

Refer to <Document: 1002801.1>  Verifying Active NAS Replication Licenses

Step 2 - Confirm replication methodology used is supported.

Three types of file replication can been performed: one-to-one (One, or multiple, volume(s) from a single source system replicated to multiple volumes on a single target system), many-to-one (Multiple volumes from multiple source systems replicated to multiple volumes on a single target system), and two-way (cross-mirror) (Target systems may also be source systems but with different volumes).

Refer to <Document: 1005123.1>  What is the Sun StorEdge[TM] File Replicator software?

Step 3 - Verify sufficient buffer space is available on source volume.

The File Replicator mirroring feature uses a transaction journal as a mechanism to buffer file system changes as they are sent from the master (source) to the mirror (target) system. The size of the transaction journal should be large enough to buffer all file system transactions.

Refer to <Document: 1002802.1>  Verifying NAS Replication Source Volume Buffer Space

Step 4 - Verify sufficient space is available on target system.

During the process to create the mirrored volume on the Master (source) system, a request is sent to the Mirror (target) server to select appropriately-sized devices on which to create the mirror. If sufficient space cannot be found on a (target) LUN to create the mirror, the mirror creation will fail.

Refer to <Document: 1008206.1>  Verifying NAS Replication Space on Mirror (Target) System

Step 5 - Confirm LUN status is optimal.

Faulty operation of any LUNs involved in the mirror configuration will affect the File Replicator processing.

Refer to <Document: 1008205.1>  Verifying LUN Status on NAS

Step 6 - Verify network is operational and is configured correctly for replication.

A fully-functional network connection is required between the master (source) NAS server and the target (mirror) NAS server. Any operational issues with the 'mirror network' will directly affect the functioning of the mirror process.

Refer to <Document: 1012813.1> Verifying Sun StorageTek[TM] NAS Replication Network Configuration

Step 7 - Confirm sufficient time is allowed for synchronization to complete.

Under normal circumstances, the most network-intensive processing occurs during the initial block replication - this consists of a block-by-block copy of the source volume disk blocks to the target system (allocated) LUN. Sufficient time must be allowed (and file volume write activity possibly restricted) for this process to complete.

Refer to <Document: 1002803.1>  NAS Replication - Time required for 'sync' completion

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At this point, if you have validated that each troubleshooting step above is true for your environment and the problem still exists, further troubleshooting is required. For additional support contact Sun Support


Product
Sun StorageTek 5320 NAS Appliance
Sun StorageTek 5210 NAS Appliance
Sun StorageTek 5310 NAS Appliance
Sun StorageTek 5310 NAS Gateway System
Sun StorageTek 5310 NAS Gateway/Cluster System
Sun StorageTek 5320 NAS Gateway/Cluster System

Internal Comments
This document contains normalized content and is managed by the the Domain Lead(s) of the respective domains. To notify content owners of a knowledge gap contained in this document, and/or prior to updating this document, please contact the domain engineers that are managing this document via the “Document Feedback” alias(es) listed below:

storage-nas-domain@sun.com

The Knowledge Work Queue for this article is KNO-STO-NAS.

Refer to <Document: 1005474.1>  Data Collection techniques for Sun StorageTek[TM] 5000 Series NAS (for troubleshooting)

for collecting data in the first instance which will assist the timely resolution of the issue.

normalized, NAS, 5210, 5310, 5320, replication failure, mirroring failure
Previously Published As
88730

Change History
Date: 2010-03-26
User Name: 79977
Action: FID:466545
Comments: Took the opportunity of a currency check alongside fixing the FID

Date: 2007-10-01
User Name: 7058
Action: Approved


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