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Oracle® ZFS Storage Appliance Administration Guide
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Document Information

Using This Documentation

Chapter 1 Oracle ZFS Storage Appliance Overview

Chapter 2 Status

Chapter 3 Initial Configuration

Chapter 4 Network Configuration

Chapter 5 Storage Configuration

Chapter 6 Storage Area Network Configuration

Chapter 7 User Configuration

Chapter 8 Setting ZFSSA Preferences

Chapter 9 Alert Configuration

Chapter 10 Cluster Configuration

Chapter 11 ZFSSA Services

Chapter 12 Shares, Projects, and Schema

Chapter 13 Replication

Chapter 14 Shadow Migration

Data Migration

Traditional Data Migration

Migration via Synchronization

Migration via External Interposition

Shadow Migration

Shadow migration behavior

Restrictions on Shadow Source

Shadow File System Semantics During Migration

Identity and ACL Migration

Shadow Migration Management

Creating a Shadow Filesystem

Managing Background Migration

Handling Migration Errors

Monitoring Migration Progress

Canceling Migration

Snapshots of Shadow File Systems

Backing Up Shadow File Systems

Replicating Shadow File Systems

Shadow Migration Analytics

Shadow Migration Requests

Shadow Migration Bytes

Shadow migration operations

Migrating Local File Systems

Shadow Migration Tasks

Testing Potential Shadow Migration

Migrating Data from an Active NFS Server

Chapter 15 CLI Scripting

Chapter 16 Maintenance Workflows

Chapter 17 Integration


Managing Background Migration

When a share is created, it will automatically begin migrating in the background, in addition to servicing inline requests. This migration is controlled by the shadow migration service. There is a single global tunable which is the number of threads dedicated to this task. Increasing the number of threads will result in greater parallelism at the expense of additional resources.

The shadow migration service can be disabled, but this should only be used for testing purposes, or when the active of shadow migration is overwhelming the system to the point where it needs to be temporarily stopped. When the shadow migration service is disabled, synchronous requests are still migrated as needed, but no background migration occurs. With the service disabled no shadow migration will ever complete, even if all the contents of the filesystem are read manually. It is highly recommended to always leave the service enabled.