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Replication Repository Virtual Disks, Replication Relationships, Data Replication

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Replication Repository Virtual Disks A replication repository virtual disk is a special virtual disk in the storage array that is created as a resource for the RAID controller module owner of the primary virtual disk in a remote replicated pair. The RAID controller module stores replication information on this virtual disk, including information about remote writes that are not yet complete. The RAID controller module can use this information to recover from RAID controller module resets and the accidental powering down of the storage arrays. When you activate the Remote Replication premium feature on the storage array, you create two replication repository virtual disks, one for each RAID controller module in the storage array. An individual replication repository virtual disk is not needed for each remote replication. When you create the replication repository virtual disks, you specify the location of the virtual disks. You can either use existing free capacity, or you can create a disk group for the virtual disks from unconfigured capacity and then specify the RAID level. Because of the critical nature of the data being stored, do not use RAID Level 0 as the RAID level of replication repository virtual disks. The required size of each virtual disk is 128 MB, or 256 MB total for both replication repository virtual disks of a dual-RAID controller module storage array. In previous versions of the Remote Replication premium feature, the replication repository virtual disks required less disk storage space and needed to be upgraded to use the maximum amount of replication relationships. Replication Relationships Before you create a replication relationship, you must enable the Remote Replication premium feature on both the primary storage array and the secondary storage array. You must also create a secondary virtual disk on the secondary site if one does not already exist. The secondary virtual disk must be a standard virtual disk of equal or greater capacity than the associated primary virtual disk. When secondary virtual disks are available, you can establish a replication relationship in the MD storage management software by identifying the primary virtual disk and the storage array that contains the secondary virtual disk. When you first create the replication relationship, a full synchronization automatically occurs, with data from the primary virtual disk copied in its entirety to the secondary virtual disk. Data Replication The RAID controller modules manage data replication between the primary virtual disk and the secondary virtual disk. This process is transparent to host machines and applications. This section describes how data is replicated between the storage arrays that are participating in Remote Replication. This section also describes the actions taken by the RAID controller module owner of the primary virtual disk if a link interruption occurs between storage arrays. Write Modes When the RAID controller module owner of the primary virtual disk receives a write request from a host, the RAID controller module first logs information about the write to a replication repository virtual disk, and then writes the data to the primary virtual disk. The RAID controller module then initiates a remote write operation to copy the affected data blocks to the secondary virtual disk at the secondary storage array. The Remote Replication premium feature provides two write mode options that affect when the I/O completion indication is sent back to the host: Synchronous and Asynchronous. Synchronous Write Mode Synchronous write mode provides the highest level security for full data recovery from the secondary storage array in the event of a disaster. Synchronous write mode does reduce host I/O performance. When this write mode is selected, 68

Section	Page
Dell PowerVault Modular Disk Storage Arrays CLI Guide	3
About The Command Line Interface	11
How To Use The Command Line Interface	11
Usage Notes	12
CLI Commands	12
Command Line Parameters	14
Formatting Considerations	18
Detailed Error Reporting	18
Exit Status	19
Usage Examples	20
About The Script Commands	23
Script Command Structure	23
Script Command Synopsis	25
Recurring Syntax Elements	26
Usage Guidelines	30
Adding Comments To A Script File	30
Configuring A Storage Array	33
Configuring A Storage Array	33
Determining What Is On Your Storage Array	34
Saving A Configuration To A File	35
Using The Create Virtual Disk Command	36
Using The Auto Configure Command	38
Modifying Your Configuration	40
Setting The Storage Array Password	40
Setting Up SMTP And SNMP Alerts	40
Setting The RAID Controller Module Clocks	41
Setting The Storage Array Host Type	41
Setting Modification Priority	42
Assigning Global Hot Spares	42
Selecting The Event Levels For Alert Notifications	43
Configuring Alert Notifications	43
Using The Snapshot Feature	45
Using Host Servers To Create An Initial Snapshot Virtual Disk	46
Creating A Snapshot Virtual Disk	46
Enabling The Snapshot Virtual Disk Feature	47
Creating A Snapshot Virtual Disk With User-Assigned Physical Disks	47
Preparing Host Servers To Create An Initial Snapshot Virtual Disk	47
Creating The Initial Snapshot Virtual Disk	48
Creating A Snapshot Virtual Disk With Software-Assigned Physical Disks	49
Creating A Snapshot Virtual Disk By Specifying A Number Of Physical Disks	49
User-Defined Parameters	50
Names Of Snapshot Virtual Disks And Repository Virtual Disks	52
Changing Snapshot Virtual Disk Settings	53
Stopping And Deleting A Snapshot Virtual Disk	53
Re-creating The Snapshot Virtual Disk	54
Preparing Host Servers To Re-create A Snapshot Virtual Disk	54
Re-creating A Snapshot Virtual Disk	54
Using The Virtual Disk Copy Feature	57
Creating A Virtual Disk Copy	58
Enabling The Virtual Disk Copy Feature	58
Determining Virtual Disk Copy Candidates	58
Creating A Virtual Disk Copy	58
Preparing Host Servers To Create A Virtual Disk Copy	59
Copying The Virtual Disk	59
Viewing Virtual Disk Copy Properties	60
Changing Virtual Disk Copy Settings	61
Recopying A Virtual Disk	62
Preparing Host Servers To Recopy A Virtual Disk	62
Recopying The Virtual Disk	62
Stopping A Virtual Disk Copy	63
Removing Copy Pairs	63
Interaction With Other Features	64
Storage Partitioning	64
Snapshot Virtual Disks	64
Using The Remote Replication Premium Feature	67
How Remote Replication Works	67
Replication Repository Virtual Disks	68
Replication Relationships	68
Data Replication	68
Link Interruptions Or Secondary Virtual Disk Errors	69
Resynchronization	69
Creating A Remote Replicated Pair	70
Performance Considerations	70
Enabling The Remote Replication Premium Feature	71
Activating The Remote Replication Premium Feature	71
Determining Candidates For A Remote Replicated Pair	73
Creating A Remote Replicated Pair	73
Changing Remote Replication Settings	74
Suspending And Resuming A Replication Relationship	75
Removing A Replication Relationship	75
Deleting A Primary Virtual Disk Or A Secondary Virtual Disk	76
Disabling The Remote Replication Premium Feature	76
Deactivating The Remote Replication Premium Feature	76
Interaction With Other Premium Features	76
Snapshot Virtual Disks	77
Virtual Disk Copy	77
Storage Partitioning	77
Virtual Disk Expansion	78
Maintaining A Storage Array	79
Routine Maintenance	79
Running A Media Scan	79
Running A Consistency Check	80
Resetting A RAID Controller Module	80
Enabling RAID Controller Module Data Transfer	81
Resetting Battery Age	81
Removing Persistent Reservations	81
Synchronizing RAID Controller Module Clocks	81
Locating Physical Disks	81
Performance Tuning	82
Monitoring Performance	82
Changing RAID Levels	83
Changing Segment Size	83
Defragmenting A Disk Group	83
Troubleshooting and Diagnostics	83
Collecting Physical Disk Data	84
Diagnosing A RAID Controller Module	84
Recovery Operations	84
Setting RAID Controller Module Operational Mode	85
Changing RAID Controller Module Ownership	85
Initializing A Physical Disk	85
Reconstructing A Physical Disk	86
Initializing A Virtual Disk	86
Redistributing Virtual Disks	86
Script Commands	89
Command Formatting Rules	89
Firmware Compatibility Levels	91
Commands Listed By Function	91
Disk Group Commands	91
Enclosure Commands	91
Host Topology Commands	91
iSCSI Commands	92
Physical Disk Commands	92
RAID Controller Module Commands	93
Remote Replication Commands	93
Session Command	94
Show String Command	94
Snapshot Commands	94
Storage Array Commands	94
Virtual Disk Commands	95
Virtual Disk Copy Commands	96
Commands Listed Alphabetically	96
Activate Remote Replication Feature	96
Activate Storage Array Firmware	99
Autoconfigure Storage Array	99
Autoconfigure Storage Array Hot Spares	100
Check Remote Replication Status	100
Check Virtual Disk Consistency	101
Clear Physical Disk Port Statistics	102
Clear Storage Array Configuration	102
Clear Storage Array Core Dump	103
Clear Storage Array Event Log	103
Clear Storage Array Firmware Pending Area	103
Clear Storage Array Recovery Mode	104
Clear Virtual Disk Reservations	104
Clear Virtual Disk Unreadable Sectors	104
Configure Automatic Support Bundle Collection	105
Create Disk Group	105
Create Disk Pool	109
Create Host	111
Create Host Group	111
Create Host Port	111
Create iSCSI Initiator	112
Create RAID Virtual Disk (Automatic Physical Disk Select)	113
Create RAID Virtual Disk (Free Capacity Base Select)	114
Create RAID Virtual Disk (Manual Physical Disk Select)	116
Create RAID Virtual Disk On A Disk Pool	119
Create Remote Replication	120
Create Snapshot Virtual Disk	122
Scheduling Snapshots	126
Create Storage Array Security Key	127
Create Virtual Disk Copy	129
Deactivate Remote Replication	130
Delete Disk Group	130
Delete Disk Pool	131
Delete Host	131
Delete Host Group	131
Delete Host Port	132
Delete iSCSI Initiator	132
Delete Snapshot Virtual Disk or Delete Snapshot Virtual Disk Schedule	133
Delete Virtual Disk	133
Delete Virtual Disk On A Disk Pool	134
Diagnose RAID Controller Module	135
Diagnose RAID Controller Module iSCSI Host Cable	136
Diagnose Remote Replication	137
Disable Storage Array Feature	138
Display Automatic Support Bundle Collection Configuration	138
Display Support Bundle Collection Schedule	138
Download Enclosure Management Module Firmware	139
Download Physical Disk Firmware	139
Download Storage Array Firmware/NVSRAM	140
Download Storage Array Physical Disk Firmware	141
Download Storage Array NVSRAM	142
Enable Disk Group Security	142
Enable Disk Pool Security	142
Enable RAID Controller Module Data Transfer	143
Enable Storage Array Feature	143
Increase Virtual Disk Capacity On A Disk Pool	144
Load Storage Array DBM Database	144
Recopy Virtual Disk Copy	145
Re-Create Remote Replication Repository Virtual Disk	146
Re-Create Snapshot	148
Reduce Disk Pool Capacity	150
Remove Remote Replication	150
Remove Virtual Disk Copy	151
Remove Virtual Disk LUN Mapping	151
Repair Virtual Disk Consistency	152
Replace Physical Disk	152
Reset RAID Controller Module	153
Reset Storage Array Battery Install Date	154
Reset Storage Array iSCSI Baseline	154
Reset Storage Array SAS PHY Baseline	155
Reset Storage Array Virtual Disk Distribution	155
Resume Remote Replication	155
Resume Snapshot Rollback	156
Revive Disk Group	156
Revive Disk Pool	157
Revive Physical Disk	157
Save Enclosure Log Data	157
Save Physical Disk Channel Fault Isolation Diagnostic Status	158
Save Physical Disk Log	158
Save RAID Controller Module NVSRAM	158
Save Storage Array Configuration	159
Save Storage Array Events	160
Save Storage Array iSCSI Statistics	161
Save Storage Array Performance Statistics	161
Save Storage Array SAS PHY Counts	162
Save Storage Array State Capture	162
Save Storage Array Support Data	162
Schedule Support Bundle Collection Configuration	163
Scheduling Snapshots	164
Set Disk Group	165
Set Disk Group Forced State	167
Set Disk Pool	167
Set Enclosure Attribute	168
Set Enclosure Identification	168
Set Foreign Physical Disk to Native	169
Set Host	169
Set Host Channel	170
Set Host Group	171
Set Host Port	171
Set iSCSI Initiator	172
Set iSCSI Target Properties	172
Set Physical Disk Channel Status	173
Set Physical Disk Hot Spare	174
Set Physical Disk State	174
Set RAID Controller Module	175
Set Remote Replication	177
Set Session	179
Set Snapshot Virtual Disk	180
Set Storage Array	181
Set Storage Array Enclosure Positions	183
Set Storage Array ICMP Response	184
Set Storage Array iSNS Server IPv4 Address	184
Set Storage Array iSNS Server IPv6 Address	185
Set Storage Array iSNS Server Listening Port	185
Set Storage Array Learn Cycle	185
Set Storage Array Redundancy Mode	186
Set Storage Array Security Key	186
Set Storage Array Time	187
Set Storage Array Unnamed Discovery Session	187
Set Virtual Disk	187
Set Virtual Disk Copy	190
Show Current iSCSI Sessions	191
Show Disk Group	192
Show Disk Group Export Dependencies	192
Show Disk Group Import Dependencies	193
Show Disk Pool	193
Show Host Ports	193
Show Physical Disk	194
Show Physical Disk Channel Statistics	195
Show Physical Disk Download Progress	196
Show RAID Controller Module	196
Show RAID Controller Module NVSRAM	197
Show Remote Replication Virtual Disk Candidates	198
Show Remote Replication Virtual Disk Synchronization Progress	198
Show Storage Array	199
Show Storage Array Auto Configure	200
Show Storage Array Host Topology	201
Show Storage Array LUN Mappings	202
Show Storage Array Negotiation Defaults	202
Show Storage Array Unconfigured iSCSI Initiators	202
Show Storage Array Unreadable Sectors	203
Show String	203
Show Virtual Disk	203
Show Virtual Disk Action Progress	205
Show Virtual Disk Copy	205
Show Virtual Disk Copy Source Candidates	206
Show Virtual Disk Copy Target Candidates	206
Show Virtual Disk Performance Statistics	206
Show Virtual Disk Reservations	207
Start Configuration Database Diagnostic	207
Start Disk Group Blink	208
Start Disk Group Defragment	208
Start Disk Group Export	208
Start Disk Group Import	209
Start Disk Pool Locate	209
Start Enclosure Blink	209
Start iSCSI DHCP Refresh	210
Start Physical Disk Blink	210
Start Physical Disk Channel Blink	211
Start Physical Disk Channel Fault Isolation Diagnostics	211
Start Physical Disk Initialize	212
Start Physical Disk Reconstruction	212
Start Remote Replication Synchronization	213
Start Secure Physical Disk Erase	213
Start Snapshot Rollback	213
Stop Snapshot Rollback	214
Start Storage Array Blink	214
Start Storage Array iSCSI Refresh	214
Start Virtual Disk Initialization	215
Stop Configuration Database Diagnostic	215
Stop Disk Group Blink	215
Stop Disk Pool Locate	216
Stop Enclosure Blink	216
Stop Physical Disk Blink	216
Stop Physical Disk Channel Blink	216
Stop Physical Disk Channel Fault Isolation Diagnostics	216
Stop Snapshot	217
Stop Storage Array Blink	217
Stop Storage Array iSCSI Session	217
Stop Storage Array Physical Disk Firmware Download	217
Stop Virtual Disk Copy	218
Suspend Remote Replication	218
Validate Storage Array Security Key	219
Sample Script Files	221
Configuration Script Example 1	221
Configuration Script Example 2	222
CLI Command Updates	225
New Commands	225

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Replication Repository Virtual Disks

A replication repository virtual disk is a special virtual disk in the storage array that is created as a resource for the RAID

controller module owner of the primary virtual disk in a remote replicated pair. The RAID controller module stores

replication information on this virtual disk, including information about remote writes that are not yet complete. The RAID

controller module can use this information to recover from RAID controller module resets and the accidental powering

down of the storage arrays.

When you activate the Remote Replication premium feature on the storage array, you create two replication repository

virtual disks, one for each RAID controller module in the storage array. An individual replication repository virtual disk is

not needed for each remote replication.

When you create the replication repository virtual disks, you specify the location of the virtual disks. You can either use

existing free capacity, or you can create a disk group for the virtual disks from unconfigured capacity and then specify

the RAID level.

Because of the critical nature of the data being stored, do not use RAID Level 0 as the RAID level of replication

repository virtual disks. The required size of each virtual disk is 128 MB, or 256 MB total for both replication repository

virtual disks of a dual-RAID controller module storage array. In previous versions of the Remote Replication premium

feature, the replication repository virtual disks required less disk storage space and needed to be upgraded to use the

maximum amount of replication relationships.

Replication Relationships

Before you create a replication relationship, you must enable the Remote Replication premium feature on both the

primary storage array and the secondary storage array. You must also create a secondary virtual disk on the secondary

site if one does not already exist. The secondary virtual disk must be a standard virtual disk of equal or greater capacity

than the associated primary virtual disk.

When secondary virtual disks are available, you can establish a replication relationship in the MD storage management

software by identifying the primary virtual disk and the storage array that contains the secondary virtual disk.

When you first create the replication relationship, a full synchronization automatically occurs, with data from the

primary virtual disk copied in its entirety to the secondary virtual disk.

Data Replication

The RAID controller modules manage data replication between the primary virtual disk and the secondary virtual disk.

This process is transparent to host machines and applications. This section describes how data is replicated between

the storage arrays that are participating in Remote Replication. This section also describes the actions taken by the

RAID controller module owner of the primary virtual disk if a link interruption occurs between storage arrays.

Write Modes

When the RAID controller module owner of the primary virtual disk receives a write request from a host, the RAID

controller module first logs information about the write to a replication repository virtual disk, and then writes the data to

the primary virtual disk. The RAID controller module then initiates a remote write operation to copy the affected data

blocks to the secondary virtual disk at the secondary storage array.

The Remote Replication premium feature provides two write mode options that affect when the I/O completion indication

is sent back to the host: Synchronous and Asynchronous.

Synchronous Write Mode

Synchronous write mode provides the highest level security for full data recovery from the secondary storage array in

the event of a disaster. Synchronous write mode does reduce host I/O performance. When this write mode is selected,