Hitachi MK-97DF8018-00 manual

i Product Version Document Organization Getting Help Table of Contents F AST F IND L INKS MK-97DF8018-00 Hitachi Simple Modular Storage Copy-on- Write SnapShot User’s Guide #[...]

ii Hitachi Simple Modular Storage Copy-on-Write SnapShot User’s Guide © 2007 Hitachi Data Systems Corpor ation, ALL RIGHTS RESERVED Notice: No part of this publication may be reproduced or transm itted in any form or by any means, electronic or mechanical, including photocopying and recording, or stored in a database or retrieval system for any [...]

Preface iii Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Preface This document provides instructions on assessing your snapshot requirements, designing an im plementation to meet those requirements, and implementing and oper ating Copy -on- W rite Snapshot software using the Stor age Navigator 2 gr aphical user interface. [...]

iv Preface Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Document Revision Level This section provides a history of the revision changes to this document. • Safety and Warnings This document uses the following symb ols to dr aw attention to important safety and operational information. The Danger , Electric Shock, and ESD[...]

Preface v Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Document Organization The following table provides an ov e rview of the contents and organization of this document. Click the chapter title in the first column to go to that chapter . The first page o f every chapte r or appendix contains a brief list of the contents o[...]

vi Preface Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Document Conventions The following table describes the typogr aphic conventions used in this document. • Convention for Storage Capacity Values Storage capacity v alues for hard di sk drives (HDDs) in Hitachi Data Systems’ stor age products are calculated based on[...]

Preface vii Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Getting Help If you hav e questions after reading th is guide, contact an Hitachi Data Systems authorized service provider[H1] or visit the Hitachi Data S ystems support website, http://support.hds.com. Support Contact Information If you purchased this product from a[...]

viii Preface Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

Contents ix Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Document Revision Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Safety and Warnings . . . . [...]

x Contents Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Lifespan Based on Back up Requirements . . . . . . . . . . . . . . . . . . . . . . . 2-3 Lifespan Based on Busi ness Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 Establishing the Number of V- VOLs that Are Required . . . . . . . . . . . . . . . . 2[...]

Contents xi Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide 7 Monitoring and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 Monitoring SnapShot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 Monitoring Pair Status . . . . . . . . . . . . . . . . . . . . .[...]

xii Contents Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

SnapShot O verview 1–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide 1 SnapShot Overview Snapshot creates virtual copie s of data volumes within Hitachi Simple Modular Storage systems. These copies can be used for recovery from logical errors. They are identica l to the original volume at the point in time they were taken[...]

1–2 SnapShot O verview Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Copy-on-Write SnapShot Software Hitachi’ s Copy-on-W rite Snapshot software creates virtual backup copies of any data volume within the Simple Modular Storage systems with minimal impact to host service or performanc e levels. These snapshots are suita[...]

SnapShot O verview 1–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • Figure 1-1: SnapShot functional components The following sections describe how these components work together . How SnapShot Works SnapShot creates a virtual duplicate volume of another volume. This volume “pair” is created when you: • Select a[...]

1–4 SnapShot O verview Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Volume Pairs—P-VOLs and V-VOLs A volume pair is a relationship established by SnapShot between two volumes. A pair consists of a producti on v o lume, which contains the original data and is called the primary volume (P- VOL), and from 1 to 32 virtual [...]

SnapShot O verview 1–5 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • Figure 1-2: V-VOL Maintains SnapShot Data[...]

1–6 SnapShot O verview Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Data Pools After a snapshot, the V -VOL maintains a static copy of the P- VOL even as new writes are updating the P-VOL. T o do this, before an updated block is written to the P- VOL, SnapShot sends th e data tha t is being replaced to the data pool. P o[...]

2 Planning and Design 2–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Planning and Design A backup insures that a volume with bad or missing data can be restored. With SnapShot you create copies of y our production data that can be used for backup and other uses. Creating a backup system that fully supports business con[...]

2–2 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide The Plan and Design Workflow The SnapShot planning effort consists of finding the number of V -VO Ls your organization requires for the P- VOL, the V- VOL(s)’ lifespan — how long they must be held before being updated again — the frequency that sn[...]

Planning and Design 2–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Ideally , a business desires no data loss. In the real world, disasters occur and data is lost. Y ou or your organization’ s decision makers must decide the number of business tr ansactions, the number of hours required to key in lost data, and so on.[...]

2–4 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • If the snapshot is to be used as a disk -based backup available for online recovery , you can determine the lifespan by multiplying the number of generations of backup y ou want to keep on line by the snapshot frequency . F or example: Gener ations [...]

Planning and Design 2–5 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Establishing Data Pool Size The data pool holds data from the P- VO L that is being replaced. By holding this original data in the data pool , the mirror image of the V -VOL is maintained at the time of the snapshot. Y ou determine the size of the data [...]

2–6 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide 2. At the end of the period, con vert th e data to MB/second, if it is not already so, and import into a spreadsheet tool. Figure 2-3 shows collected r aw data, in megabytes per second in 10 minute segments. • Figure 2-3: Raw Data Example in MB/ s ec [...]

Planning and Design 2–7 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide b. Pr es s E nt er . This instructs the tool to calcul ate the average v alue in cells B2 through B7 and populates C4 with that data. c. Copy the value in C4. d. Highlight cells C5 to the last C cell in the last row of workload data in the spreadsheet. [...]

2–8 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide 5. Calculate the base data pool size for your primary/virtual volumes by multiplying the MB size of one V -VOL in Step 4 by the number of V -VOLs, which was established earlier . For example: 90,000 MB x 4 V -VOLS = 360,000 MB This is the base data pool[...]

Planning and Design 2–9 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide 3. Multiply the base data pool size by the number of V -VOLs. Thus: 4 V-VOLs x 625 GB = 2500 GB (2.5 TB) . Data Pool Key Points • The data pool must be on same controller as the P-VOL and V- VOL(s). • Data pool capacity should be at least 20 GB. •[...]

2–10 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Total PVOL size = 173.25 GB Total data pool size = 163.2 GB Thus: 173.25 GB / 5 = 34.65 GB 34.65 GB + 163.2 GB = 197.85 GB In this exampl e, the SnapShot ma ximum capacity is 197.85 GB, well below the maximum supported capacity of 800 GB. If ShadowImag[...]

Planning and Design 2–11 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide b. Right-click the disk whose HLUN you want to know , then select Properties . The number displayed to the ri ght of “LUN” in the dialog window is the HLUN. 2. Identify HLUN-to-LUN Mapping. a. In Start Storage Navigator Modula r 2, select the desir[...]

2–12 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Linux and LVM Configuration A host cannot recognize both a P-VOL and its V -VOL at the same time. Map the P- VOL and V- VOL to separate hosts. Windows Server 2003/Window s 2000 and Dynamic Disk Observe the following when using Windows Server 2003 dyn a[...]

Planning and Design 2–13 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide If any one of the dynamic disks is left unhidden, a Miss ing drive occurs. When this occurs, delete it manually using the diskpart delete command (CCI required). •[...]

2–14 Planning and Design Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • Copy dynamic disk volumes that consist of two or more LUs only after hiding all LUs from a host. When the copy is completed, you can have them recognized by a host. • • A dynamic disk cannot be used with a cluster (MSCS, VCS, etc.). • A dynam[...]

3 Requirements 3–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Requirements This chapter describes minimu m operational requirements.  System Requiremen ts  Supported Platforms[...]

3–2 Requirements Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide System Requirements Table 3-1 shows the minimum requirements for SnapShot. See Appendix B, SnapShot Specifications for additional information. Supported Platforms Table 3-2 shows the supported platforms and operating system ve rsions required for SnapShot. Tab[...]

4 Enabling and Disabling SnapShot 4–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Enabling and Disabling SnapShot SnapShot is bundled with the Simple Modular Storage system. It must be enabled before using. SnapShot can also be disabled.  Enabling/Disabling SnapShot[...]

4–2 Enabling and Disabling SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Enabling/Disabling SnapShot To enable/disable SnapShot 1. In the Navigator 2 GUI, select the array where you w ant to enable SnapShot and click the Show & Configure Array button. 2. In the tree view , click Settings , then click Licenses[...]

Enabling and Disabling SnapShot 4–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • 7. When ready , click the Yes, I have read ... check box at the bottom of the message, then click Reboot Array . The reboot time displays. If the Storage system does not respond after 15 minutes, check its condition. • 8. When rebootin[...]

4–4 Enabling and Disabling SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

5 Configuring SnapShot 5–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Configuring SnapShot This chapter describes the steps for setting up SnapShot.  Configuration Workflow  Assign Volumes for the Data Pool  Set Up the Virtual Volume (V -VOL) (manual method)[...]

5–2 Configuring SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Configuration Workflow The following configuration tasks must be complete d for SnapShot functions to become operational. The P- VOL should be set up in your Simple Modular Stor age system prior to SnapShot configuration. See Appendix B, SnapShot Speci[...]

Configuring SnapShot 5–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Set Up the Virtual Volume (V-VOL) (manual method) When the Backup Wizard in the Naviga tor 2 GUI is used, V- VO Ls are created and set up automatically . Y ou do not need to perform any V -VOL setup . If you are not using the Backup Wizard but the C re[...]

5–4 Configuring SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

6 Using SnapShot 6–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Using SnapShot This chapter describes the Snap Shot data replication workflow and processes. Details are prov ided for in-system replication along with sample scenarios using SnapShot functionality .  SnapShot Replication Workflow  Back Up Your Volum[...]

6–2 Using SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide SnapShot Replication Workflow F ollowing the initial creation of the SnapShot pair , which is a one time operation, a SnapShot workflow incl udes the following basic processes: • Back up a volume • Update the V -VOL • R estore the P-VOL from the V -VOL[...]

Using SnapShot 6–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide 4. Existing volumes in the arr ay are listed in the Primary Volu me box. Click the button next to the LUN that you want to back up , then click Next . The Prepare Secondary V olume s creen displays. 5. The system will create a secondar y v o lume (SnapShot v[...]

6–4 Using SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide 10. In the Group Assignment area, you have the option of assigning the new pair to a consistency group . See Consistency Group (CTG) on page 1-6 for a description. Do one of the following: - If you do not want to assign the pair to a consist e ncy group, lea[...]

Using SnapShot 6–5 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide 2. From the Replication tree, select the Local R e plication icon. The Pairs screen displays. 3. Select the pair that you want to update and click the Resync Pair button at the bottom of the sc reen. The operation may take sev e ral minutes, depending on the[...]

6–6 Using SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Use the V-VOL for Tape Backup, Testing, Reports, Etc. Y our snapshot image (V- V OL) can be used to fulfill a number of data management task s performed on a se co ndary server . These management tasks include backing up production data to tape, using the da[...]

Using SnapShot 6–7 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Edit Pairs, Data Pool Y ou can edit certain information concerning a pair and a data pool. • F or pairs, you can change the name, group name, and copy pace. • F or data pools, you can increase the size, edit capacity threshold, and add LUs (volumes). T o[...]

6–8 Using SnapShot Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide 2. Select the SnapShot L ogical Units icon in the tree view . 3. In the Logical Units for Snapshot list, select the V- VOL tha t you want to delete. 4. Click Delete LU for SnapShot . A message appea rs. 5. Click Close . The V -VOL is deleted. To delete a dat[...]

7 Monitoring and Maintenance 7–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Monitoring and Maintenance Y our business depends on the data protection provided by SnapShot. It is important that data pool capacity is sufficient to handle the differential data from your P- VOLs. If a data pool should become full, the V- VO[...]

7–2 Monitoring and Maintenance Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Monitoring SnapShot The SnapShot data pool must have sufficient capacity to handle the differential data demands placed on it. Y ou must insure that sufficient capacity is always available for the write workload by closely monitoring the followin[...]

Monitoring and Maintenance 7–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Monitoring Data Pool Usage The data pools should be monitored frequently . To monitor data pool usage level (Advanced users using CLI, see the Storage Navigator Modular 2 Command Line Interface (CLI) User’s Guide .) 1. In Navigator 2 GUI, selec[...]

7–4 Monitoring and Maintenance Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

8 Troubleshooting 8–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Troubleshooting T wo types of problem can be experienced with a SnapShot system: pair failure and data pool capacity ex ceeded. This chapter discusses the causes and provides solutions for these problems.  Pair Failure  Data Pool Capacity Exceeded[...]

8–2 Troubleshooting Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Pair Failure A pair failure can hav e two causes: • A hardware failure affecting either the pair v olumes or data pool • A data pool whose capacity is exceeded To determine the cause of pair failure 1. Check the status of the data pool whose associated [...]

Troubleshooting 8–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Data Pool Capacity Exceeded When your data pool capacity is exceed ed, y ou must increase th e size of the data poo l. Mo st li kely , th e PO OL FU LL condition has caused pair failures as well. T o address thes e problems, please see Recovering from Pair [...]

8–4 Troubleshooting Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

A Operations Using CLI A–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Operations Using CLI • This appendix describes Stor age Na viga tor 2 Command Line Interface (CLI) procedures for Sn apshot enabling, configuration and operations.  Enabling and Disabling SnapShot  Operations for SnapShot Configuration  Pe[...]

A–2 Operations Using CLI Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Enabling and Disabling SnapShot SnapShot is bundled with the Simpl e Modular Storage system. Y ou must enabled it before using. The following describes the enabling/disabling procedure. • 1. From the command prompt, register th e array in which the s[...]

Operations Using CLI A–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Snapshot Enable/Disable is complete. Operations for SnapShot Configuration Setting the POOL Up to 64 data pools can be designated for each subsystem, by assigning a logical unit that has been created and formatted. Up to 64 logical units can be assigne[...]

A–4 Operations Using CLI Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide 3. Execute the aupool command to v erify that the Data Pool has been created. R efer to the following example. • 4. When deleting the logical unit set as the Data P ool, it is necessary to delete all Snapshot images (V- VOLs). T o delete an existing [...]

Operations Using CLI A–5 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide 3. T o delete an existing SnapShot logical unit, refer to the following example of deleting SnapShot logica l unit 1000. When deleting the V- VOL, the pair state must be Simplex. • Performing SnapShot CLI Operations The aureplicationlocal command ope[...]

A–6 Operations Using CLI Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Updating SnapShot Logical Unit T o update the V- VOL: 1. From the command prompt, register the subsystem to which you want to update the SnapShot pair , then connect to the subsystem. 2. Execute the aureplicationlocal command update the pair . Change t[...]

Operations Using CLI A–7 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • 3. Execute aureplicationlocal to restore the pair . Refer to the following example. • V -VOL to P- VOL is re stored. Releasing SnapShot Pairs T o release the Snapshot pair and change the status to Simplex: 1. From the command prompt, register the[...]

A–8 Operations Using CLI Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide Changing Pair Information Y ou can change the pair name, group name, and/or copy pace. 1. From the command prompt, register the subsystem to which you want to change the SnapShot pair in formation, then connect to the subsystem. 2. Execute the aureplic[...]

Operations Using CLI A–9 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Sample Back Up Script for Windows This section provides sample scrip t for backing a volume on Windows. • • echo off REM Specify the registered name of the arrays set UNITNAME=Array1 REM Specify the group name (Specify “Ungroup” if the pair doe[...]

A–10 Operations Using CLI Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

B SnapShot Specifications B–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide SnapShot Specifications This appendix provides external specifications for SnapShot Snapshot.  General Specifications[...]

B–2 SnapShot Specifications Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide General Specifications Table B-1 lists external specifications for SnapShot. • Table B-1: General Spec ifications Item Specification Simple Modular Storage model SMS100 (For dual conf iguration only .) Host interface iSCSI Number of pairs SMS100: [...]

SnapShot Specifications B–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide R eduction of data pool capacity Possible only when all the pairs that use the data pool have been released. Expansion of data pool volume No. Formatting of v olumes in a pair No. P airing with an expanded volu me Only P- VOL can be expanded Formatt[...]

B–4 SnapShot Specifications Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide[...]

Glossary–1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ Glossary This glossary provides definitions for replication terms as well as terms related to the technology that supports your Hitachi Simple Modular Storage 100 arr ay . Click the letter of the glossary section to disp[...]

Glossary–2 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ A array A set of hard disks mounted in a single enclosure and grouped logically together to function as one contiguous stor age space. asynchronous Asynchronous data communications operate between a computer and various [...]

Glossary–3 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ CLI See command line interface. cluster A group of disk sectors. The operating system assigns a unique number to each cluster and then keeps track of files according to which clusters they use. cluster capacity The total[...]

Glossary–4 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ configuration definition file The configur ation definition file de scribes the system configuration for making CCI operational in a T rueCopy Extended Distance Software environment. The conf iguration definiti on file i[...]

Glossary–5 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ D data pool One or more disk volumes designa ted to temporarily store un- transferred differential data (in the local storage system or snapshots of backup data in the remote storage system). The saved snapshots are usef[...]

Glossary–6 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ dual copy The process of simultaneously upda ting a P-VOL and S- VOL while using a single write operation. duplex The transmission of data in either one or two directions. Duplex modes are full-duplex and half -duplex. F[...]

Glossary–7 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ fibre channel A gigabit- speed network technology primarily used for stor age networking. firmware Software embedded into a storage device . It may also be referred to as Microcode. full duplex The concurrent transmissio[...]

Glossary–8 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ iSCSI Internet- Small Com puter Systems Interface, a T CP/IP protocol for carrying SCSI commands over IP networks. iSNS Internet- Small Com puter Systems Interface, a T CP/IP protocol for carrying SCSI commands over IP n[...]

Glossary–9 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ M metadata In sophisticated data systems, the metadata -- the contextual information surrounding the data -- will also be very sophisticated, capable of answering many question s that help understand the data. microcode [...]

Glossary–10 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ paired volume T wo volumes that are paired in a disk array . parity The technique of checking w hether data has been lost or corrupted when it's transferred from one place to another , such as between storage units[...]

Glossary–11 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ R RAID R e dundant Arra y of Independent Disks, a disk array in which part of the physical storage capacity is used to store redundant information about user data stored on the remainder of the storage capacity . The re[...]

Glossary–12 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ S SAS Serial Attached SCSI, an ev olution of parallel SCSI into a point -to-point serial peripheral interface in whic h co ntrollers are linked directly to disk drives. SAS deli vers improved performance over traditiona[...]

Glossary–13 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ S-VOL determination Independent of update operations, S- VOL determination replicates the S- VOL on the rem ote storage system. This process occurs at the end of each update cycle and a pre-determin ed copy of S- VOL da[...]

Glossary–14 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide • ABCD E F G H I JK LM NO P Q RS T U VW XYZ write order guarantee Ensures that data is updated in an S- VOL, in the same order that it is updated in the P- VOL, particularly when there are multiple write operations in one update cycle. This feature is critical to[...]

Index-1 Hitachi Simple M odular Storage Copy -on-Write SnapShot User’s Guide Index A assessing business needs 2-2 assigning pairs to a consistency group 6-4 B backup script, CLI A-9 C CCI, version 3-2 Command Line Interface changing pair information A-8 creating pairs A-5 enabling and disabling SnapShot A-2 releasing (deleting) pairs A- 7 restori[...]

Index-2 Hitachi Simple Modular Storag e Copy -on-Write SnapShot User’s Guide O overview 1-1 P pair status definitions 7-2 monitoring 7-2 pairs, assigning to a consistency group 6-4 planning the SnapShot system 2-1 platforms, supported 3-2 Pool Full, recovery from 8-2 P-VOLs and V-VOLs 1-4 R recovering from Pool Full, hardware failure 8- 2 releasi[...]

1 Hitachi Simple Modu lar Storage Copy -on-Write Snap Shot User’s Guide[...]

MK-97DF8018-00 Hitachi Data Systems Corporate Headquarters 750 Central Expressway Santa Clara, California 95050-2627 U.S.A. Phone: 1 408 970 1000 www .hds.co m info@hds.com Asia Pacific and Americas 750 Central Expressway Santa Clara, California 95050-2627 U.S.A. Phone: 1 408 970 1000 info@hds.com Europe Headquarters Sefton Park Stoke P oges Buckin[...]