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Dell PowerVault MD3000i Command Line Interface Guide - Page 89

Snapshot Virtual Disks, The Snapshot Virtual Disk feature can be used with the Virtual Disk Copy

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After you create a virtual disk copy, the target virtual disk automatically becomes read-only to hosts to ensure that the data is preserved. Hosts that have been mapped to a target virtual disk do not have write access to the virtual disk, and any attempt to write to the read-only target virtual disk results in a host I/O error. If you want hosts to have write access to the data on the target virtual disk, use the set virtualDiskCopy command to disable the read-only attribute for the target virtual disk. Snapshot Virtual Disks A snapshot virtual disk is a point-in-time image of a virtual disk. It is typically created so that an application, such as a backup, can access the snapshot virtual disk and read the data while the source virtual disk remains online and accessible to hosts. NOTICE: Before using the source virtual disk of a snapshot virtual disk as your target, you must disable all snapshot virtual disks associated with the source virtual disk. By disabling the snapshot virtual disks, you avoid altering the snapshot data if the source virtual disk is changed. Creating a snapshot virtual disk automatically creates a snapshot repository virtual disk. The snapshot repository virtual disk stores information about the data that has changed since the snapshot virtual disk was created. Snapshot repository virtual disks cannot be selected as a source virtual disk or target virtual disk in a virtual disk copy. The virtual disk for which the point-in-time image is created is the source virtual disk and must be a standard virtual disk in the storage array. You can select snapshot virtual disks as the source virtual disk for a virtual disk copy. Selecting a snapshot virtual disk is a good use of this feature, because it enables complete backups without significant impact to the storage array I/O. However, some I/O processing resources are lost to the copy operation. The Snapshot Virtual Disk feature can be used with the Virtual Disk Copy feature to back up data on the same storage array and to restore the data on the snapshot virtual disk back to its original source virtual disk. Using the Virtual Disk Copy Feature 89

Section	Page
Contents	3
About the Command Line Interface	13
How to Use the Command Line Interface	14
Usage Notes	15
CLI Commands	16
Command Line Parameters	18
Formatting Considerations	24
Detailed Error Reporting	24
Exit Status	25
Usage Examples	27
About the Script Commands	29
Script Command Structure	30
Script Command Synopsis	32
Recurring Syntax Elements	34
Usage Guidelines	40
Adding Comments to a Script File	41
Configuring a Storage Array	43
Configuring a Storage Array	44
Determining What is on Your Storage Array	44
Saving a Configuration to a File	47
Using the Create Virtual Disk Command	48
Using the Auto Configure Command	53
Modifying Your Configuration	55
Setting the Storage Array Password	56
Setting Up SMTP and SNMP Alerts	56
Setting the RAID Controller Module Clocks	57
Setting the Storage Array Host Type	57
Setting Modification Priority	58
Assigning Global Hot Spares	59
Using the Snapshot Feature	61
Using Host Servers to Create an Initial Snapshot Virtual Disk	63
Creating a Snapshot Virtual Disk	63
Enabling the Snapshot Virtual Disk Feature	64
Creating a Snapshot Virtual Disk with User-Assigned Physical Disks	64
Preparing Host Servers to Create an Initial Snapshot Virtual Disk	65
Creating the Initial Snapshot Virtual Disk	66
Creating a Snapshot Virtual Disk with Software-Assigned Physical Disks	67
Creating a Snapshot Virtual Disk by Specifying a Number of Physical Disks	69
User-Defined Parameters	70
Names of Snapshot Virtual Disks and Repository Virtual Disks	72
Changing Snapshot Virtual Disk Settings	73
Stopping and Deleting a Snapshot Virtual Disk	74
Re-creating the Snapshot Virtual Disk	75
Preparing Host Servers to Re-create a Snapshot Virtual Disk	75
Re-creating a Snapshot Virtual Disk	76
Using the Virtual Disk Copy Feature	77
Creating a Virtual Disk Copy	78
Enabling the Virtual Disk Copy Feature	79
Determining Virtual Disk Copy Candidates	79
Creating a Virtual Disk Copy	79
Preparing Host Servers to Create a Virtual Disk Copy	80
Copying the Virtual Disk	81
Viewing Virtual Disk Copy Properties	82
Changing Virtual Disk Copy Settings	83
Recopying a Virtual Disk	84
Preparing Host Servers to Recopy a Virtual Disk	85
Recopying the Virtual Disk	86
Stopping a Virtual Disk Copy	87
Removing Copy Pairs	87
Interaction with Other Features	88
Storage Partitioning	88
Snapshot Virtual Disks	89
Maintaining a Storage Array	91
Routine Maintenance	91
Running a Media Scan	91
Running a Consistency Check	93
Resetting a RAID Controller Module	94
Enabling RAID Controller Module Data Transfer	94
Resetting Battery Age	94
Removing Persistent Reservations	94
Synchronizing RAID Controller Module Clocks	95
Locating Physical Disks	95
Performance Tuning	95
Monitoring Performance	96
Changing RAID Levels	97
Changing Segment Size	97
Defragmenting a Disk Group	98
Troubleshooting and Diagnostics	98
Collecting Physical Disk Data	98
Diagnosing a RAID Controller Module	99
Recovery Operations	100
Setting RAID Controller Module Operational Mode	100
Changing RAID Controller Module Ownership	101
Initializing a Physical Disk	101
Reconstructing a Physical Disk	102
Initializing a Virtual Disk	102
Redistributing Virtual Disks	103
Script Commands	105
Command Formatting Rules	106
Commands Listed by Function	108
Disk Group Commands	108
Enclosure Commands	108
Host Topology Commands	109
iSCSI Commands	109
Physical Disk Commands	110
RAID Controller Module Commands	111
Session Command	111
Show String Command	111
Snapshot Commands	111
Storage Array Commands	111
Virtual Disk Commands	113
Virtual Disk Copy Commands	113
Commands Listed Alphabetically	114
Accept Storage Array Pending Topology	114
Activate Storage Array Firmware	114
Autoconfigure Storage Array	114
Autoconfigure Storage Array Hot Spares	116
Check Disk Consistency	117
Clear Physical Disk Channel Statistics	118
Clear Storage Array Configuration	118
Clear Storage Array Event Log	118
Clear Storage Array Firmware Pending Area	119
Clear Virtual Disk Reservations	119
Create Host	120
Create Host Group	121
Create Host Port	121
Create iSCSI Initiator	122
Create RAID Virtual Disk (Automatic Physical Disk Select)	123
Create RAID Virtual Disk (Free Capacity Base Select)	126
Create RAID Virtual Disk (Manual Physical Disk Select)	128
Create Snapshot Virtual Disk	131
Create Virtual Disk Copy	135
Delete Disk Group	137
Delete Host	138
Delete Host Group	138
Delete Host Port	139
Delete iSCSI Initiator	139
Delete Virtual Disk	140
Diagnose RAID Controller Module	141
Disable Storage Array Feature	144
Download Enclosure Management Module Firmware	144
Download Physical Disk Firmware	145
Download Storage Array Firmware/NVSRAM	146
Download Storage Array NVSRAM	147
Download Storage Array Physical Disk Firmware	148
Enable RAID Controller Module	149
Enable Storage Array Feature Key	149
Recopy Virtual Disk Copy	150
Recover RAID Virtual Disk	151
Re-create Snapshot	153
Remove Virtual Disk Copy	155
Remove Virtual Disk LUN Mapping	156
Repair Virtual Disk Consistency	157
Reset RAID Controller Module	157
Reset Storage Array Battery Install Date	158
Reset Storage Array iSCSI Baseline	158
Reset Storage Array SAS PHY Baseline	159
Reset Storage Array Virtual Disk Distribution	159
Revive Disk Group	160
Revive Physical Disk	160
Save Enclosure Log Data	161
Save Physical Disk Log	161
Save RAID Controller Module NVSRAM	162
Save Storage Array Configuration	162
Save Storage Array Events	163
Save Storage Array iSCSI Statistics	164
Save Storage Array Performance Statistics	165
Save Storage Array SAS PHY Counts	165
Save Storage Array State Capture	166
Save Storage Array Support Data	166
Set Controller	166
Set Disk Group	169
Set Enclosure Attribute	170
Set Enclosure Identification	171
Set Host	171
Set Host Group	173
Set Host Port	174
Set iSCSI Initiator	175
Set iSCSI Target Properties	176
Set Physical Disk Channel Status	177
Set Physical Disk Hot Spare	178
Set Physical Disk State	178
Set Session	179
Set Snapshot Virtual Disk	180
Set Storage Array	182
Set Storage Array Enclosure Positions	184
Set Storage Array ICMP Response	184
Set Storage Array iSNS Server IPv4 Address	185
Set Storage Array iSNS Server IPv6 Address	186
Set Storage Array iSNS Server Listening Port	187
Set Storage Array iSNS Server Refresh	188
Set Storage Array Time	188
Set Unnamed Discovery Session	188
Set Virtual Disk	189
Set Virtual Disk Copy	194
Show Current iSCSI Sessions	194
Show Disk Group	195
Show Host Ports	196
Show Physical Disk	196
Show Physical Disk Channel Statistics	198
Show Physical Disk Download Progress	199
Show RAID Controller Module	200
Show RAID Controller Module NVSRAM	201
Show Storage Array	202
Show Storage Array Autoconfigure	204
Show Storage Array Host Topology	206
Show Storage Array LUN Mappings	206
Show Storage Array Negotiation Defaults	206
Show Storage Array Pending Topology	207
Show Storage Array Unreadable Sectors	207
Show String	208
Show Unconfigured iSCSI Initiators	208
Show Virtual Disk	209
Show Virtual Disk Action Progress	210
Show Virtual Disk Copy	211
Show Virtual Disk Copy Source Candidates	212
Show Virtual Disk Copy Target Candidates	212
Show Virtual Disk Performance Statistics	212
Show Virtual Disk Reservations	213
Start Disk Group Blink	214
Start Disk Group Defragment	214
Start Enclosure Blink	215
Start iSCSI DHCP Refresh	215
Start Physical Disk Blink	216
Start Physical Disk Initialize	216
Start Physical Disk Reconstruction	217
Start Storage Array Blink	217
Start Virtual Disk Initialization	217
Stop Disk Group Blink	218
Stop Enclosure Blink	218
Stop iSCSI Session	218
Stop Physical Disk Blink	219
Stop Snapshot	219
Stop Storage Array Blink	220
Stop Storage Array Physical Disk Firmware Download	220
Stop Virtual Disk Copy	220
Sample Script Files	223
Configuration Script Example 1	223
Configuration Script Example 2	226

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Using the Virtual Disk Copy Feature

After you create a virtual disk copy, the target virtual disk automatically

becomes read-only to hosts to ensure that the data is preserved. Hosts that

have been mapped to a target virtual disk do not have write access to the

virtual disk, and any attempt to write to the read-only target virtual disk

results in a host I/O error.

If you want hosts to have write access to the data on the target virtual disk,

use the

set virtualDiskCopy

command to disable the read-only attribute for

the target virtual disk.

Snapshot Virtual Disks

A snapshot virtual disk is a point-in-time image of a virtual disk. It is typically

created so that an application, such as a backup, can access the snapshot

virtual disk and read the data while the source virtual disk remains online and

accessible to hosts.

NOTICE:

Before using the source virtual disk of a snapshot virtual disk as your

target, you must disable all snapshot virtual disks associated with the source virtual

disk. By disabling the snapshot virtual disks, you avoid altering the snapshot data if

the source virtual disk is changed.

Creating a snapshot virtual disk automatically creates a snapshot repository

virtual disk. The snapshot repository virtual disk stores information about the

data that has changed since the snapshot virtual disk was created. Snapshot

repository virtual disks cannot be selected as a source virtual disk or target

virtual disk in a virtual disk copy.

The virtual disk for which the point-in-time image is created is the source

virtual disk and must be a standard virtual disk in the storage array.

You can select snapshot virtual disks as the source virtual disk for a virtual disk

copy. Selecting a snapshot virtual disk is a good use of this feature, because it

enables complete backups without significant impact to the storage array I/O.

However, some I/O processing resources are lost to the copy operation.

The Snapshot Virtual Disk feature can be used with the Virtual Disk Copy

feature to back up data on the same storage array and to restore the data on the

snapshot virtual disk back to its original source virtual disk.