Hitachi MK-97DF8018-00 S

Glossary–12

Hitachi Simple Modular Storage Copy-on-Write SnapShot User’s Guide

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S

SAS

Serial Attached SCSI, an evolution of parallel SCSI into a point-to-point

serial peripheral interface in which controllers are linked directly to disk

drives. SAS delivers improved performance over traditional SCSI

because SAS enables up to 128 devices of different sizes and types to

be connected simultaneously.

SATA

Serial ATA is a computer bus technology primarily designed for the

transfer of data to and from hard disks and optical drives. SATA is the

evolution of the legacy Advanced Technology Attachment (ATA)

interface from a parallel bus to serial connection architecture.

secondary volume (S VOL)

A replica of the primary volume (P-VOL) at the time of a backup and is

kept on a standby storage system. Recurring differential data updates

are performed to keep the data in the S-VOL consistent with data in the

P-VOL.

SMPL

Simplex.

snapshot

A term used to denote a copy of the data and data-file organization on

a node in a disk file system. A snapshot is a replica of the data as it

existed at a particular point in time.

SNM2

See Storage Navigator Modular 2.

Storage Navigator Modular 2

A multi-featured scalable storage management application that is used

to configure and manage the storage functions of Hitachi arrays. Also

referred to as “Navigator 2”.

suspended status

Occurs when the update operation is suspended while maintaining the

pair status. During suspended status, the differential data control for

the updated data is performed in the primary volume.

S-VOL

See secondary volume.

Contents

Main MK-97DF8018-00 Hitachi Simple Modular Storage Copy-on- Write SnapShot Users Guide ii Preface iv Document Revision Level Safety and Warnings Intended Audience Product Version Release Notes Document Organization Referenced Documents vi Document Conventions Convention for Storage Capacity Values Getting Help Support Contact Information Comments Page Table of Contents 1 SnapShot Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 2 Planning and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 4 Enabling and Disabling SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 5 Configuring SnapShot. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 Page Page SnapShot Overview 12 Copy-on-Write SnapShot Software Hardware and Software Configuration Figure 1-1: SnapShot functional components How SnapShot Works 14 Volume PairsP-VOLs and V-VOLs Page 16 Data Pools Differential Management LUs (DM-LU) Consistency Group (CTG) SnapShot InterfaceStorage Navigator Modular 2 Planning and Design 22 The Plan and Design Workflow Assessing Business Needs Establishing How Often a Copy Is Made (Copy Frequency) Selecting a Reasonable Time Between Snapshots Establishing How Long a Copy Is Held (Copy Lifespan) Lifespan Based on Backup Requirements 24 Lifespan Based on Business Uses Figure 2-1: V-VOL Frequency, Lifespan Establishing the Number of V-VOLs that Are Required Establishing Data Pool Size Figure 2-2: Write workload and data pool size Measuring Workload Data 26 Figure 2-3: Raw Data Example in MB/sec Figure 2-4: Rolling Averages Calculated Using V-VOL Frequency Figure 2-5: Rolling Averages Graphed Over Raw Averages 28 Rule of Thumb Calculation Table 2-1: Workload Rates when No Measurement Data Pool Key Points Calculating Maximum Capacity 210 Operating System Considerations Identifying P-VOL and V-VOL Cluster Software, Path Switching Software Microsoft Cluster Server (MSCS) Veritas Volume Manager (VxVM) Windows 2000 Windows Server 2003 Linux and LVM Configuration Windows Server 2003/Windows 2000 and Dynamic Disk Page Page Requirements 32 System Requirements Supported Platforms Table 3-2 shows the supported platforms and operating system versions required for SnapShot. Table 3-1: Storage S Minimum Requirements Page 42 Enabling/Disabling SnapShot Page Page Configuring SnapShot 52 Configuration Workflow Assign Volumes for the Data Pool Notes on Adding a Data Pool Set Up the Virtual Volume (V-VOL) (manual method) Page Using SnapShot 62 SnapShot Replication Workflow Back Up Your VolumeCreate a Pair Using the Backup Wizard Create Pair Procedure 64 Update the V-VOL Restore the P-VOL from the V-VOL Restore from Tape 66 Use the V-VOL for Tape Backup, Testing, Reports, Etc. Edit Pairs, Data Pool Delete Pairs, V-VOLs, Data Pools 68 Test the Configuration Monitoring and Maintenance 72 Monitoring SnapShot Monitoring Pair Status Table 7-1: Pair Statuses Monitoring Data Pool Usage Expanding the Data Pool Other Methods for Lowering Data Pool Load Page Troubleshooting 82 Pair Failure Recovering from Pair Failure Due to POOL FULL Recovering from Pair Failure Due to a Hardware Failure Page Page A Operations Using CLI A2 Enabling and Disabling SnapShot Operations for SnapShot Configuration Setting the POOL A4 Setting the V-VOL Performing SnapShot CLI Operations Creating SnapShot Pairs A6 Updating SnapShot Logical Unit Restoring V-VOL to P-VOL Releasing SnapShot Pairs A8 Changing Pair Information Creating Pairs that Belong to a Group Operations Using CLI A9 Sample Back Up Script for Windows This section provides sample script for backing a volume on Windows. Page Page B2 General Specifications Table B-1 lists external specifications for SnapShot. Table B-1: General Specifications Item Specification Maximum Capacity on page 2-9 Table B-1: General Specifications Item Specification Page Glossary1 Glossary Glossary2 A B C Glossary3 Glossary4 Glossary5 D Glossary6 E F Glossary7 G I Glossary8 L Glossary9 M P Glossary10 Glossary11 R Glossary12 S Glossary13 T V W Glossary14 Index-1 Index A B C D Index-2 O P R S Page MK-97DF8018-00