Reviewing warnings for Storage Node system drive recovery

Before recovering a failed system drive of a Storage Node, you must review the following warnings.

About this task

Storage Nodes have a Cassandra database that includes object metadata. The Cassandra database might be rebuilt in the following circumstances:

  • A Storage Node is brought back online after having been offline for more than 15 days.
  • A storage volume has failed and been recovered.
  • The system drive and one or more storage volumes fails and is recovered.

When Cassandra is rebuilt, it uses information from other Storage Nodes. If too many Storage Nodes are offline, some Cassandra data may not be available. If Cassandra has been rebuilt recently, Cassandra data may not yet be consistent across the grid.

CAUTION:
Do perform this procedure if more than one Storage Node is offline, or if more than one Storage Node has a failure of any kind. Doing so might result in data loss. Contact technical support.
CAUTION:
Do not rebuild Cassandra on more than one Storage Node within a 15 day period. Rebuilding Cassandra on two or more Storage Nodes within 15 days of each other might result in data loss. Contact technical support.
CAUTION:
If this Storage Node is in read-only maintenance mode to allow for the retrieval of objects by another Storage Node with failed storage volumes, recover volumes on the Storage Node with failed storage volumes before recovering this failed Storage Node. See "Recovering from loss of storage volumes where the system drive is intact" for instructions.
Attention: If the ILM policy is configured to replicate a single copy only, and those objects are lost, they cannot be recovered. You must still perform the "Restoring object data to a storage volume" procedure to purge lost object information from the database. For more information about ILM policies, see the Administrator Guide.
Note: If you encounter a DDS alarm during recovery, see the Troubleshooting Guide for instructions to recover from the alarm by rebuilding Cassandra. After Cassandra is rebuilt, alarms should clear. If alarms do not clear, contact technical support.