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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

Understanding Shares

Storage Pools

Using Shares

Share Properties

Share Snapshots

Share Clones

Shares Space Management

Shares Space Terminology

Understanding Snapshots

File System and Project Settings

Data Quotas

Data Reservations

Space Management for Replicating LUNs

User and Group Settings

Viewing Current Usage

Viewing Current Usage in the BUI

Viewing Current Usage in the CLI

Setting User or Group Quotas

Set User or Group Quotas Using the BUI

Set User or Group Quotas Using the CLI

Identity Management

Filesystem Namespace

Namespace Nested Mountpoints

Namespace Protocol Access to Mountpoints

Namespace NFSv2 / NFSv3

Namespace NFSv4

Namespace SMB

Namespace FTP / FTPS / SFTP

Namespace HTTP / HTTPS

Shares > Shares

Working with Shares > Shares in the BUI

List of Shares

Editing a Share

Usage Statistics

Static Properties

Shares Project Panel

Creating a Share

Working with Shares > Shares in the CLI

Navigation

Share Operations

Shares > Shares CLI Properties

Shares > Shares > General - BUI Page

Space Usage

Volume Size

Thin Provisioned

Mountpoint

Read only

Update access time on read

Non-blocking mandatory locking

Data deduplication

Data compression

Checksum

Cache Device Usage

Synchronous Write Bias

Database Record Size

Additional Replication

Virus Scan

Prevent Destruction

Restrict Ownership Change

Custom Properties

Shares > Shares > Protocols - BUI Page

Shares Protocols

Share Protocols - NFS

Share Protocols - CLI

Security Modes

Character Set Encodings

Shares - SMB

Shares - iSCSI

Shares - HTTP

Shares - FTP

Shares - SFTP

Shares > Shares > Access

Access Control

Shares - Root Directory Access

Shares - User

Shares - Group

Shares - Permissions

Shares - ACL Behavior

ACL Behavior on Mode Change

ACL Inheritance Behavior

Root Directory ACL

Shares - Snapshots

Shares - Snapshot Properties

.zfs/snapshot visible

Scheduled Snapshot Label

Listing Snapshots Using the BUI

Manual Snapshots Using the BUI

Create a project level snapshot

Create a share/LUN level snapshot

Renaming a Snapshot (BUI)

Destroying a Snapshot (BUI)

Rolling back to a Snapshot (BUI)

Cloning a Snapshot (BUI)

Scheduled Snapshots Using the BUI

Manual Snapshots Using the CLI

Listing Snapshots (CLI)

Taking Manual Snapshots (CLI)

Renaming a Snapshot (CLI)

Destroying a Snapshot (CLI)

Rolling back to a Snapshot (CLI)

Cloning a Snapshot (CLI)

Listing Dependent Clones Using the CLI

Scheduled Snapshots Using the CLI

Setting the Scheduled Snapshot Label Using the CLI

Projects

Working with Projects Using the BUI

Project Fields

Editing a Project

Usage Statistics

Static Properties

Creating Projects

Working with Projects Using the CLI

Navigation

Project Operations

Selecting a Pool in a Cluster

Project Properties

Project - General

Project - General Properties

Project - Space Usage

Project - Quota

Project - Reservation

Project - Inherited Properties

Project - Custom Properties

Filesystem Creation Defaults

LUN Creation Defaults

Project Protocols

Project Access

Project Snapshots

Project Snapshot Properites

.zfs/snapshot visible

Scheduled Snapshot Label

Schemas

Customized Share Properties

Working with Schemas in the BUI

Configuring a Schema Using the BUI

Working with Schemas Using the CLI

Configuring a Schema Using the CLI

Chapter 13 Replication

Chapter 14 Shadow Migration

Chapter 15 CLI Scripting

Chapter 16 Maintenance Workflows

Chapter 17 Integration

Index

Data deduplication

Controls whether duplicate copies of data are eliminated. Deduplication is synchronous, pool-wide, block-based, and can be enabled on a per project or share basis. Enable it by selecting the Data Deduplication checkbox on the general properties screen for projects or shares. The deduplication ratio will appear in the usage area of the Status Dashboard.

Data written with deduplication enabled is entered into the deduplication table indexed by the data checksum. Deduplication forces the use of the cryptographically strong SHA-256 checksum. Subsequent writes will identify duplicate data and retain only the existing copy on disk. Deduplication can only happen between blocks of the same size, data written with the same record size. As always, for best results set the record size to that of the application using the data; for streaming workloads use a large record size.

If your data doesn't contain any duplicates, enabling Data Deduplication will add overhead (a more CPU-intensive checksum and on-disk deduplication table entries) without providing any benefit. If your data does contain duplicates, enabling Data Deduplication will both save space by storing only one copy of a given block regardless of how many times it occurs. Deduplication necessarily will impact performance in that the checksum is more expensive to compute and the metadata of the deduplication table must be accessed and maintained.

Note that deduplication has no effect on the calculated size of a share, but does affect the amount of space used for the pool. For example, if two shares contain the same 1GB file, each will appear to be 1GB in size, but the total for the pool will be just 1GB and the deduplication ratio will be reported as 2x.

Performance Warning: by its nature, deduplication requires modifying the deduplication table when a block is written to or freed. If the deduplication table cannot fit in DRAM, writes and frees may induce significant random read activity where there was previously none. As a result, the performance impact of enabling deduplication can be severe. Moreover, for some cases -- in particular, share or snapshot deletion -- the performance degradation from enabling deduplication may be felt pool-wide. In general, it is not advised to enable deduplication unless it is known that a share has a very high rate of duplicated data, and that that duplicated data plus the table to reference it can comfortably reside in DRAM. To determine if performance has been adversely affected by deduplication, enable Chapter 8, Setting ZFSSA Preferences and then use Analytics in Oracle ZFS Storage Appliance Analytics Guide to measure "ZFS DMU operations broken down by DMU object type" and check for a higher rate of sustained DDT operations (Data Duplication Table operations) as compared to ZFS operations. If this is happening, more I/O is for serving the deduplication table rather than file I/O.