HP StorageWorks Volume Shadow copy Service (VSS) Hardware Provider (HWP) for EVA Disk Arrays

Technical white paper

Table of contents

Executive summary............................................................................................................................... 2

Intended audience ............................................................................................................................... 2

Overview............................................................................................................................................ 2

VSS functionality provided for data protection......................................................................................... 2

Terminology ........................................................................................................................................ 3

EVA array business copy fundamentals .................................................................................................. 3 Different types of business copies in EVA ............................................................................................ 3 Snapshots ....................................................................................................................................... 3 SnapClone ...................................................................................................................................... 4 MirrorClone .................................................................................................................................... 5

Utilities ............................................................................................................................................... 6 Diskshadow..................................................................................................................................... 6 Demand allocated snapshot ............................................................................................................ 11 Fully allocated snapshot.................................................................................................................. 15 SnapClone .................................................................................................................................... 18 MirrorClone .................................................................................................................................. 22 MirrorClone-Snapshot..................................................................................................................... 26 Shadow copies of the multiple volumes............................................................................................. 29

Auto-recovery test .............................................................................................................................. 31

Executive summary The scope of this document includes the operations of HP StorageWorks VSS Hardware Provider for EVA for Microsoft Windows 2008 and Windows 2008 R2 Operating Systems (OS).

This document discusses about VSS infrastructure that enables application-aware shadow copy capabilities.

The objective of this document is:

Provide users with the basic knowledge needed to troubleshoot HP StorageWorks VSS Hardware Provider (HWP) for EVA disk Arrays environment on Windows 2008 and Windows 2008 R2, and confirm whether or not the EVA disk Arrays HWP is performing as expected.

Let the users have the basic knowledge needed to collect necessary information to diagnose an EVA Disk Arrays HWP problem.

This document does not take the place of the available HP StorageWorks VSS Provider for EVA Administrator and User’s Guides, which should be followed to verify correct setup and installation. Nor does it take the place of BC documentation, but is intended to provide the necessary Business Copy (BC) theory to enable the user to understand the operations of EVA Disk Array VSS HWP.

Intended audience This guide is intended for users and administrators of storage area networks (SAN) that include HP StorageWorks Enterprise Virtual Arrays (EVA). Readers should be familiar with:

SAN EVA Command View EVA Microsoft VSS framework HP MPIO

Overview Diskshadow is a simple yet powerful way to make application-consistent replicas and use them to recover lost data.

This technical white paper illustrates the Diskshadow command examples performed to confirm the HP StorageWorks VSS Provider for EVA version 6.04.00 HWP.

It is expected that the documentation included with the EVA Disk Array HWP has been consulted prior to reading this document.

VSS functionality provided for data protection Volume Shadow Copy Service (VSS) is composed of the MS VSS layer and an array’s Hardware Provider layer and the HWP is vendor specific.

VSS is the infrastructure that enables application-aware snapshot capabilities (shadow copies).

Snapshot technology provides the basis for a number of storage management solutions, including high fidelity point-in-time copies for backup, data transport, and end-user single file restores.

The HP StorageWorks VSS Provider for EVA Disk Arrays uses the EVA Array BC functionality.

2

Terminology BC (Business Copy): HP Business Copy EVA is the local replication component of the HP Enterprise Virtual Array.

VSS (Volume shadow copy service): This provides a mechanism for creating consistent point-in-time copies of data known as shadow copies.

HWP (Hardware Provider): The HWP is a vendor specific interface between the Microsoft VSS service and a vendor’s specific hardware product such as the XP Array or EVA Array.

LUN: Logical Unit Number.

Vdisk (Virtual disk): This is nothing but LUN which is created and presented to host as a block.

Snapshot: The snapshot is the point-in-time copy of the data that uses copy before write mechanism.

SnapClone: SnapClone is a complete clone copy of a specified Virtual Disk (LUN).

MirrorClone: MirrorClone provides an alternative to a snapshot by allowing the user to make a full, byte-for-byte, point-in-time copy of a source LUN. MirrorClone will track all changed blocks and can re-sync with the source LUN to create a new point-in-time copy.

CV-EVA (Command View Enterprise Virtual Array): This tool is used to create, modify, and monitor disk groups, virtual disks, logical unit numbers (LUNs), Snapshots, SnapClones, MirrorClones, and DR groups.

Array: A disk array is a disk storage system which contains multiple disk drives.

EVA: Enterprise Virtual Array.

HP MPIO: Multiple Path I/O (MPIO) allows server to use multiple paths to a storage LUN presented on a SAN.

Metadata: Metadata contains detailed information of the snapshot.

EVA array business copy fundamentals

Different types of business copies in EVA Snapshots (demand and fully-allocated) SnapClone MirrorClone

Snapshots Snapshots in EVA uses copy before write mechanism to preserve point in copies of the data. According to this concept before a write I/O is applied to the source volume the original blocks are copied to an alternate location called snapshot space.

Once the original blocks are copied to the snapshot space, the host write I/O can be applied to the source volume.

There are two types of snapshots on the EVA:

Demand allocated snapshot Fully allocated snapshot

3

Demand allocated snapshot In demand allocated snapshot, space is allocated on demand once a copy-before-write requires additional storage, hence no initial snapshot space is allocated. The space for snapshot is taken from same Vdisk group where the source Vdisk resides and no user space is allocated.

Fully allocated snapshot In fully allocated snapshot, space is not allocated but space equivalent to the size of source Vdisk is reserved for snapshot deltas.

Snapshot guidelines Follow these guidelines for using snapshots:

1. The array must have a local replication license. 2. The maximum number of snapshots per source varies based on the array controller software

version. For specifics, see HP StorageWorks EVA software compatibility reference. 3. A snapshot is created in the same disk group as the source virtual disk. 4. The redundancy (Vraid) level of a snapshot must be the same as, or lower than, the source. 5. All snapshots of the same virtual disk must be the same type (demand allocated or fully allocated)

and redundancy (Vraid) level.

Table 1: Snapshot Vdisk type

Vraid0 Vraid1 Vraid5 Vraid6

Vraid0 √ × × ×

Vraid1 √ √ √ ×

Vraid5 √ × √ ×

Source Vdisk Type

Vraid6 √ √ √ √

6. If the disk group has insufficient space for demand-allocated snapshots, the array stops writing to both the source and the snapshots.

7. Snapshots are included in the maximum number of virtual disks per array.

Snapshots cannot be created when the disk to be replicated is:

1. A snapshot 2. In the process of normalizing or being deleted

SnapClone A SnapClone is a complete clone copy of a specified Virtual Disk. It uses space that is equal to the space of the original volume.

SnapClone guidelines Follow these guidelines for using SnapClones:

1. The array must have a local replication license. 2. A SnapClone can be in a different disk group than the source. 3. The redundancy (Vraid) level of a SnapClone can be at any level relative to the source. 4. Until a SnapClone is normalized, another SnapClone of the same source cannot be created.

4

SnapClones cannot be created when the disk to be replicated is:

1. A snapshot 2. A disk that has a snapshot 3. In the process of normalizing or being deleted

MirrorClone MirrorClone provides an alternative to a snapshot by allowing the user to make a full, byte-for-byte, point-in-time copy of a source LUN that can be mounted to a secondary server. MirrorClone will track all changed blocks and can re-sync with the source LUN to create a new point-in-time copy, or can be used to instantly restore the source.

MirrorClone guidelines Follow these guidelines for using MirrorClones:

1. The array must have a local replication license. 2. A MirrorClone can be in a different disk group than the source. For optimum protection from

hardware failures, HP recommends creating a MirrorClone in a different disk group than the source. (A MirrorClone is created in the same disk group as its source, unless specified otherwise.)

3. The redundancy (Vraid) level of a MirrorClone can be the same, lower, or higher than the source. 4. The maximum number of MirrorClones per source is one. 5. A MirrorClone cannot be a member of (added to) a Data Replication (DR) group. 6. A detached MirrorClone cannot be reattached to its source.

MirrorClone cannot be created if the intended source virtual disk is:

1. A snapshot or has any snapshots. 2. Having SnapClones that are in the process of being normalized. 3. A member of a DR group. Further, when a virtual disk becomes the source of a MirrorClone, that

source virtual disk cannot be added to a DR group later.

5

Utilities

Diskshadow Diskshadow is a Microsoft provided command line VSS requestor which can be used for taking point-in-time consistent shadow copies.

Diskshadow utility is available in Windows 2008 and Windows 2008 R2 operating systems.

Figure 1: Diskshadow utility after launching

There are several separate operations of Diskshadow that users must be aware of:

1. The shadow copy creation operation, which creates the shadow copy; however the shadow copy is not visible to the server.

2. The shadow copy import operation, in which the shadow copy is made visible to the server; however the shadow copy is not usable.

3. The shadow copy expose operation, in which the shadow copy is made usable by the server by exposing it under a mount point or as a drive letter.

4. The delete shadow copy operation will delete the LUN from the CV EVA.

6

Shadow copy creation The shadow copy creation operation will create the shadow copy of the source Vdisk and the created shadow copy will be of any one type as selected in the EVA VSS configuration utility.

The procedure for creating snapshot is given below:

You can use the VSS configuration utility to configure the snap type, diskgroup, and Vraid type for shadow copy creation.

To access/launch the VDS configuration utility, select Start > Programs > Hewlett-Packard > Hardware Providers > VSS Configuration Utility for EVA.

The utility is executed from a command line by running hpevavsscfg.exe, located in \\Program Files\Hewlett-Packard\HardwareProviders\EVA\VSS.

Figure 2: HP StorageWorks VSS configuration utility for EVA

1. Reset: This resets the Diskshadow to the original state. 2. SET CONTEXT { CLIENTACCESSIBLE | PERSISTENT [ NOWRITERS ] | VOLATILE [ NOWRITERS ] }

CLIENTACCESSIBLE: This specifies to create shadow copies usable by client versions of Windows.

PERSISTENT: This specifies that shadow copy persists across program exit, reset, or reboot.

7

PERSISTENT NOWRITERS: This specifies that shadow copy is persistent and all writers are excluded.

VOLATILE: This specifies that shadow copy will be deleted on exit or reset.

VOLATILE NOWRITERS: This specifies that shadow copy is volatile and all writers are excluded.

Example: set context persistent

3. SET OPTION { [ DIFFERENTIAL | PLEX ] [ TRANSPORTABLE ]

[ [ROLLBACKRECOVER ] [ TXFRECOVER ] | [ NOAUTORECOVER ] ] }

DIFFERENTIAL: This specifies that the hardware shadow copies are differential. If the Option selected is Differential and if the snaptype selected in the Configuration Utility is

either Fully-allocated or Demand-allocated, then whatever has been selected in the Configuration Utility is the snaptype created.

If the Option selected is Differential and if the snaptype selected in the Configuration Utility is neither Fully-allocated nor Demand-allocated, then Fully-allocated snapshot is created by default.

PLEX: This specifies that the hardware shadow copies are plex. If the Option selected is Plex, then irrespective of snaptype selected in the Configuration Utility,

SnapClone will be created.

TRANSPORTABLE: This specifies that the hardware snapshot is not imported or exposed to the host after creation.

ROLLBACKRECOVER: This uses this flag to signal writers to auto recover.

TXFRECOVER: This requests VSS to make the shadow copy transactionally consistent during creation.

NOAUTORECOVER: This stops writers and the file system from performing any recovery.

Example: set option transportable

4. Set metadata <MetaData.cab>: This sets the name and location of the shadow copy creation metadata file which is used to transfer shadow copies from one computer to another.

Example: set metadata snapshottype_date_time.cab

5. Add volume <volume>: This adds the volume for the shadow copy creation. At least one volume is required for shadow copy creation.

Example: add volume d

6. Create: This starts the shadow copy creation process, using the current context and option settings.

The complete step for snapshot creation with the example command

Example:

RESET SET CONTEXT PERSISTENT SET OPTION TRANSPORTABLE SET METADATA SNAPSHOTTYPE_DATE_TIME.CAB ADD VOLUME D: CREATE

8

Shadow copy import The import operation will import the shadow copy to the server. Diskpart or any other device discovery tool will recognize the shadow copy as a new disk; the device will not be exposed to the file system for usage.

The procedure for importing shadow copy is:

Load metadata <MetaData.cab>: This loads a metadata .cab file prior to importing a transportable shadow copy or loads the writer metadata in the case of a restore.

Import: This imports a transportable shadow copy from a loaded metadata file into the system. The complete step for snapshot creation with the example command

Example: LOAD METADATA SNAPSHOTTYPE_DATE_TIME.CAB IMPORT

Shadow copy expose The shadow copy expose operation will expose the shadow copy for usage by a server via either a mount point, or a drive letter.

A mount point may be created by first ensuring the proposed mount point is clean by deleting it and then creating the mount point afresh.

The procedure for exposing shadow copy is:

Expose : <ShadowID> {<Drive:> | <MountPoint>} This exposes a persistent shadow copy with a drive letter or mount point. You can specify an alias by using the % symbol if the alias exists in the current environment.

Note: The shadow ID can be obtained by loading the metadata file.

Example: EXPOSE %VSS_SHADOW_1% K:

Shadow copy delete The shadow copy delete operation will return the environment to its initial condition.

The procedure for deleting shadow copy is:

Delete shadows [all | set <SetID> | id <ShadowID> | exposed {<Drive> | <MountPoint>}]

All: This option deletes all shadow copies.

Set <SetID>: This option deletes the shadow copies in the Shadow Copy Set of the given ID. You can also specify an alias by using the % symbol if the alias exists in the current environment.

id <ShadowID>: This option deletes a shadow copy of the given ID. You can specify an alias by using the % symbol if the alias exists in the current environment.

exposed {<Drive> | <MountPoint>}: This option deletes the shadow copy exposed at the specified drive letter or mount point.

Note: The shadow ID and set ID can be obtained by loading the metadata file.

9

Example:

DELETE SHADOWS ID {AA1C3008-6692-497C-91A0-6D4CF5A6A780} DELETE SHADOWS SET {BF4C88A7-0BD0-488C-8B75-F3260C1BE109} DELETE SHADOWS EXPOSED D:

The complete procedure of creating shadow copy, importing, exposing it with some drive letter and finally deleting the same shadow copy is shown in the following screen shot.

Figure 3: Process of shadow copy creation, importing, exposing, and deletion using Diskshadow utility

10

Demand allocated snapshot Steps for creating the demand allocated snapshot

Step 1. Launch the configuration utility and select the demand allocated snapshot option.

Figure 4: Configuration utility after selecting demand allocated snapshot type

Step 2. Go to command prompt and execute Diskshadow.

Step 3. Execute the following commands to create shadow copy.

RESET SET CONTEXT PERSISTENT SET OPTION TRANSPORTABLE SET METADATA SNAPSHOTTYPE_DATE_TIME.CAB ADD VOLUME D: CREATE

11

Figure 5: Process of demand allocated snapshot creation, importing, exposing using Diskshadow utility

12

Figure 6: Disk management tool showing LUN created with drive letter (E :) assigned to the same

13

Figure 7: CV EVA showing demand allocated snapshot creation

14

Fully allocated snapshot Steps for creating the fully allocated snapshot

Step 1. Load the configuration utility and select the fully allocated snapshot.

Figure 8: Configuration utility after selecting fully allocated snapshot type

Step 2. Go to command prompt and execute Diskshadow.

Step 3. Execute the following commands to shadow copy.

RESET SET CONTEXT PERSISTENT SET OPTION TRANSPORTABLE SET METADATA SNAPSHOTTYPE_DATE_TIME.CAB ADD VOLUME D: CREATE

15

Figure 9: Process of fully allocated snapshot creation, importing, exposing using Diskshadow utility

16

Figure 10: CV EVA showing fully allocated snapshot creation

17

SnapClone Steps for creating SnapClone

Step 1. Load the configuration utility and select the SnapClone.

Figure 11: Configuration utility after selecting SnapClone

Step 2. Go to command prompt and execute Diskshadow.

Step 3. Execute the following commands to shadow copy.

RESET SET CONTEXT PERSISTENT SET OPTION TRANSPORTABLE SET METADATA SNAPSHOTTYPE_DATE_TIME.CAB ADD VOLUME D: CREATE

18

Figure 12: Process of SnapClone creation, importing, exposing using Diskshadow utility

19

Figure 13: Disk management tool showing LUN created with drive letter (E:) assigned to the same

20

Figure 14: CV EVA showing SnapClone creation with Vraid6

21

MirrorClone Steps for creating MirrorClone

Step 1. Load the configuration utility and select the MirrorClone.

Figure 15: Configuration utility after selecting MirrorClone

Step 2. Go to command prompt and execute Diskshadow.

Step 3. Execute the following commands to shadow copy.

RESET SET CONTEXT PERSISTENT SET OPTION TRANSPORTABLE SET METADATA SNAPSHOTTYPE_DATE_TIME.CAB ADD VOLUME D: CREATE

22

Figure 16: Process of MirrorClone creation, importing, exposing using Diskshadow utility

23

Figure 17: Disk management tool showing LUN created with drive letter (J:) assigned to the same

24

Figure 18: CV EVA showing MirrorClone creation with Vraid1

25

MirrorClone-Snapshot Steps for creating MirrorClone-Snapshot

Step 1. Load the configuration utility and select the MirrorClone-Snapshot.

Figure 19: Configuration utility after selecting MirrorClone-Snapshot type

Step 2. Go to command prompt and execute Diskshadow.

Step 3. Execute the following commands to shadow copy.

RESET SET CONTEXT PERSISTENT SET OPTION TRANSPORTABLE SET METADATA SNAPSHOTTYPE_DATE_TIME.CAB ADD VOLUME D: CREATE

26

Figure 20: Process of MirrorClone—SnapClone creation importing, exposing using Diskshadow utility

27

Figure 21: CV EVA showing MirrorClone—Snapshot creation with Vraid1 and Fractured

28

Shadow copies of the multiple volumes Similar to creating shadow copy of single volume we can also create shadow copy for more than one volume as shown below, where we need to keep adding the volume that need shadow copy. In the example below, we added 5 volumes (d, e, g, h, i) for shadow copy creation.

Figure 22: Process of creating, importing shadow copy for multiple volumes

29

Different ways to delete shadow copy 1. Exposed volume is deleted using delete shadows exposed <drive letter>. 2. Deleting the shadow copy using the shadow copy ID which is obtained while creating shadow

copy. 3. Deleting the shadow copy using the shadow copy set ID which is obtained while creating shadow

copy.

Figure 23: Different ways in which shadow copy can be deleted

30

Auto-recovery test Auto-recovery allows writers a time to update components in a shadow copy before the shadow copy is permanently changed to read-only.

Figure 24: Auto-recovery test

31

To understand operations of HP StorageWorks VSS Hardware Provider for EVA please visit:

1. http://h18006.www1.hp.com/products/storageworks/vdsvsshard/ 2. http://technet.microsoft.com/en-us/library/cc772172(WS.10).aspx

© Copyright 2010 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.

Microsoft and Windows are U.S. registered trademarks of Microsoft Corporation.

4AA0-2143ENW, April 2010

Share with colleagues