The following registry entries are associated with the SIOS DataKeeper service or driver and can be viewed using Regedt32. The first section contains entries that may be modified; the second section contains entries that are for viewing only and should not be modified.

Registry Entries that MAY be Modified

HKEY_LOCAL_MACHINE\SYSTEM

\CurrentControlSet

\Services

\ExtMirr

\Parameters

\Volumes

\{Volume GUID}

\Targets

\{Target IP}

The SIOS DataKeeper driver uses the Parameters key and those below it. The values within the Parameters key (denoted with *) are global for all volumes on the system. The values under each of the Target IP registry keys (denoted with †) are specific to a mirror only. Values denoted with both * and † appear under both keys. (The target-specific value overrides the global value in this case.)

BandwidthThrottle †

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\BandwidthThrottle
Name Type Default Data
BandwidthThrottle REG_DWORD 0
Specifies the maximum amount of network bandwidth (in kilobits per second) that a particular mirror is allowed to use. A value of 0 means unlimited.

BitmapBaseDir *

*Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\BitmapBaseDir *
Name Type Default Data
BitmapBaseDir REG_SZ C:\%EXTMIRRBASE%\Bitmaps (usually C:\Program Files\SIOS\DataKeeper\Bitmaps but may be different when upgrading a system or if you install SIOS DataKeeper to a different path)
Specifies a directory where SIOS DataKeeper stores its Intent Log files. (Note: The drive letter must be in uppercase.) To disable the intent log feature, clear this registry entry (set it to an empty string) on all current and potential mirror endpoint servers. Disabling the intent log requires a reboot on each of these systems in order for this setting to take effect.

BitmapBytesPerBlock

Locations:

For New Mirrors: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\BitmapBytesPerBlock

For Existing Mirrors: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\BitmapBytesPerBlock

Note: If editing this entry under Parameters, all NEW mirrors created will inherit this value. If editing this entry under a {Target IP}, the value pertains to that one Target only. {Target IP} values override Parameter values.

Name Type Default Data
BitmapBytesPerBlock REG_DWORD 65536 (0×10000)

Specifies the number of bytes that are represented as dirty in a DataKeeper Intent Log bitmap when a write request occurs. A single bit in the bitmap represents 65536 bytes, and the BitmapBytesPerBlock indicates the effective block size, which may be represented as multiple bits. Increasing this value can improve replication performance in some environments – in particular with workloads that perform sequential writes, on systems with relatively high-latency Bitmap storage. A larger block size means that fewer writes to the bitmap file will occur with sequential writes that are smaller than the adjusted block size. A larger block size will not noticeably help performance in environments where writes are primarily random, and may not help on systems with fast, low-latency bitmap storage. Also, a larger block size may result in larger amounts of data to resync in the event of a system failure.

Note: The minimum value of BitmapBytesPerBlock is 65536 – any value less than this is treated as 65536. There is no maximum value enforced.

Note: BitmapBytesPerBlock does not affect the rate of mirror resync.

Compression Level †

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\CompressionLevel
Name Type Default Data
CompressionLevel REG_DWORD 0
Specifies the compression level for the given mirror. Valid values are 0 to 9. Level 0 is “no compression”. Values from 1 to 9 specify increasingly CPU-intensive levels of compression. Compression level 1 is a “fast” compression – it does not require as much CPU time to compress the data, but results in larger (less compressed) network packets. Level 9 is the maximum amount of compression – it results in the smallest network packets but requires the most CPU time. The level can be set to somewhere in between, to balance CPU usage and network efficiency based on your system, network and workload.

DontFlushAsyncQueue *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\DontFlushAsyncQueue
Name Type Default Data
DontFlushAsyncQueue REG_SZ empty <drive letter>> [<drive letter>]
Allows the user to specify a volume or volumes that should not flush their async queues when the driver receives a flush request. This value should contain the drive letter(s) of the volume(s) to which this applies. Drive letters may be adjacent to each other (i.e. XY), or space separated (i.e. X Y), with no colons. After updating this registry value, execute the READREGISTRY command so that DataKeeper immediately starts using the new value. (Note: When setting DontFlushAsyncQueue, data and database logs should be on the same partition.)

PingInterval *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\PingInterval
Name Type Default Data
PingInterval REG_DWORD 3000 (0xBB8)
Specifies the interval in milliseconds between pings. Use a higher value for Wide Area Networks (WANs) or unreliable networks. Along with the MaxPingMisses, you may customize them to adjust mirroring to the network performance.

MaxResyncPasses *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\MaxResyncPasses
Name Type Default Data
MaxResyncPasses REG_DWORD 200 (0xc8)

Specifies the maximum number of resync passes before SIOS DataKeeper will give up trying to resynchronize the mirror while there is traffic on the source volume. In every pass, SIOS DataKeeper marks the volume blocks that were written to during the pass. In the next pass, it will send to the target only the marked blocks.

Note: In order for any changes to take effect a system reboot is required.

NotificationIconUpdateStatus

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\NotificationIconUpdateStatus
Name Type Default Data
NotificationIconUpdateStatus REG_SZ true
Allows the user to turn off status update checks performed by all instances of the DataKeeper Notification Icon on a machine. This value should contain either true or false. Disabling the Notification Icon via its context menu will set this entry to false.

ResyncReads

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\ResyncReads
Name Type Default Data
ResyncReads REG_DWORD 20 (0×14)

This value represents the maximum number of disk blocks that can be in the process of being read and sent to the target system during mirror resynchronization. Changing this value may change the speed of mirror resynchronizations.

Note: This tunable applies to synchronous and asynchronous mirrors.

TargetPortBase *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\TargetPortBase
Name Type Default Data
TargetPortBase REG_DWORD 10000

Specifies the base TCP port number for target volume connections. This number may need to be adjusted if the default port is used by another service or is blocked by a firewall. The actual port that the target listens on is calculated as follows:

Port = TargetPortBase + (Volume Letter – A:)

For example:

TargetPortBase = 10000

Volume Letter = H

Port = 10000 + (H: -A:) = 10007

TargetPortIncr *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\TargetPortIncr
Name Type Default Data
TargetPortIncr REG_DWORD 256

Specifies the increment to the base TCP port number. This is used only when a TCP port is found to be in use. For example, if the target is attempting to listen on port 10005 and that port is in use, it will retry listening on port 10005 + TargetPortIncr.

TargetDispatchPort * †

Locations:

On Target System:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\TargetDispatchPort

On Source System Creating Mirror to Above Target:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\TargetDispatchPort

AND

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\(Target IP}\TargetDispatchPort

Name Type Default Data
TargetDispatchPort REG_DWORD 9999

There are two places where this should be set if you are changing the dispatch port from 9999. On the target system, place it in the ExtMirr\Parameters key. The new setting will apply to all existing and new targets on that server. A target reboot is required when the target Parameters key has been changed for this setting to take effect. On any source system that will be creating the mirror to this target, place it in the ExtMirr\Parameters key and also in the ExtMirr\Parameters\Targets\TargetIP key if the mirror already exists. Note: Make sure the ports are the SAME on both the source and the target.

A firewall port must also be opened manually on all source and target servers for the new dispatch port to work.

VssQuiesceWaitTimeoutMs *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\VssQuiesceWaitTimeoutMs
Name Type Default Data
VssQuiesceWaitTimeoutMs REG_DWORD 60000
Specifies the amount of time (in milliseconds) the DataKeeper service will wait for a VSS Snapshot Source Initiate request to complete. The VSS Snapshot Source Initiate request uses VSS to quiesce the data on snapshotted volumes.

WriteQueueByteLimitMB

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\WriteQueueByteLimitMB
Name Type Default Data
WriteQueueByteLimitMB REG_DWORD 0

Specifies the maximum number of bytes that can be allocated for the write queue of this mirror (expressed in megabytes – multiples of 1048576 bytes). The value “0” means “no limit”. During periods of high disk write activity, if this mirror’s write queue grows to a level which reaches the WriteQueueByteLimitMB, the SIOS DataKeeper driver momentarily pauses the mirror, drains the queue and automatically starts a partial resync. After updating this registry value, execute the READREGISTRY command so that DataKeeper immediately starts using the new value.

This value is used during transmission of volume data to the target, when the mirror is in the Mirroring state as well as when the mirror is in the Resync state. You should ensure that the ResyncReads value (see below), which specifies the number of 64KB (65536 byte) blocks that can be put on the Write Queue during resync, does not exceed the limit specified by WriteQueueByteLimitMB. Multiply ResyncReads by 65536, then divide by 1048576 – the resulting value must not exceed WriteQueueByteLimitMB if WriteQueueByteLimitMB is not set to 0.

This value can be used in conjunction with WriteQueueHighWater (see below). If both limits are set to nonzero values, then the mirror will be paused if either of them is reached. If one is set to 0 and one is not, then the nonzero limit is the only one that is enforced. If both are set to 0, then the mirror’s write queue is not limited at all (this is not recommended – the WriteQueue uses Nonpaged memory).

Note: This tunable applies to synchronous and asynchronous mirrors. You can monitor the mirroring behavior using the SIOS DataKeeper Performance Monitor counters – specifically the Queue Current Bytes value – and set this limit accordingly.

WriteQueueHighWater * †

Locations:

For New Mirrors:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\WriteQueueHighWater

AND

For Existing Mirrors:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\WriteQueueHighWater

Note: If editing this entry under Parameters, all NEW mirrors created will inherit this value. If editing this entry under Target, the value pertains to that one Target only. Any Target values override Parameter values.

Name Type Default Data
WriteQueueHighWater REG_DWORD 20000 (0×4e20)

Specifies the maximum number of write requests – not the number of bytes – that can be stored in this mirror’s write queue. The value “0” means “no limit”. During periods of high disk write activity, if this mirror’s write queue length reaches this value, the SIOS DataKeeper driver momentarily pauses the mirror, drains the queue and automatically starts a partial resync. After updating this registry value, execute the READREGISTRY command so that DataKeeper immediately starts using the new value.

This value is used during transmission of volume data to the target, when the mirror is in the Mirroring state as well as when the mirror is in the Resync state. You should ensure that the ResyncReads value (see below), which specifies the number of blocks that can be put on the Write Queue during resync, does not exceed the limit specified by WriteQueueHighWater if WriteQueueHighWater is not set to 0.

This value can be used in conjunction with WriteQueueByteLimitMB. If both limits are set to nonzero values, then the mirror will be paused if either of them is reached. If one is set to 0 and one is not, then the nonzero limit is the only one that is enforced. If both are set to 0, then the mirror’s write queue is not limited at all (this is not recommended – the WriteQueue uses Nonpaged memory).

Note: This tunable applies to synchronous and asynchronous mirrors. You can monitor the mirroring behavior using the SIOS DataKeeper Performance Monitor counters – specifically the Queue Current Length value – and set this limit accordingly.

WriteQueueLowWater * †

Note: This setting has been replaced by ResyncReads and is no longer used.

Locations:

For New Mirrors:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\WriteQueueLowWater

AND

For Existing Mirrors:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\{Target IP}\WriteQueueLowWater

Note: If editing this entry under Parameters, all NEW mirrors created will inherit this value. If editing this entry under Target, the value pertains to that one Target only. Any Target values override Parameter values.

Name Type Default Data
WriteQueueLowWater REG_DWORD 150 (0×96)

SnapshotLocation *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\SnapshotLocation
Name Type Default Data
SnapshotLocation REG_SZ <drive letter>
Specifies the folder where the target snapshot file for this volume will be stored.

TargetSnapshotBlocksize *

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\TargetSnapshotBlocksize
Name Type Default Data
TargetSnapshotBlocksize REG_DWORD None

DataKeeper target snapshot uses a default block size of 64KB for all entries that are written to the snapshot file. This block size can be modified by creating this TargetSnapshotBlocksize registry key.

The value should always be set to a multiple of the disk sector size, which is usually 512 bytes. Certain workloads and write patterns can benefit from changing the block size. For example, a volume that is written in a sequential stream of data (e.g. SQL Server log files) can benefit from a larger block size. A large block size results in fewer reads from the target volume when consecutive blocks are written. But a volume that is written in a random pattern may benefit from a smaller value or the default 64KB. A smaller block size will result in less snapshot file usage for random write requests.

Registry Entries that SHOULD NOT be Modified

The following registry entries are listed for informational purposes only. They should NOT be modified.
_____________________________________________________________

HKEY_LOCAL_MACHINE\SYSTEM

\CurrentControlSet

\Services

\ExtMirrSvc

This key is the base key for the service. All values directly under this key are used by the operating system to load the service. These should NOT be modified or else the service may not load correctly. The service does not use these values internally. More information on these specific keys can be obtained in the regentry.hlp file in the Windows Resource Kit.

ErrorControl

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirrSvc\ErrorControl
Name Type Default Data
ErrorControl REG_DWORD 1 (Do NOT Modify)
This value specifies what the system should do in the event the service fails to load. The default value of 1 tells the system to ignore the failure and continue booting the system. Changing this value may prevent the system from starting.

DisplayName

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirrSvc\DisplayName
Name Type Default Data
DisplayName REG_SZ SIOS DataKeeper (Do NOT Modify)
This value specifies the name of the service to be displayed in the Control Panel\Services window.

ImagePath

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirrSvc\ImagePath
Name Type Default Data
ImagePath REG_EXPAND_SZ C:\<DK_Install_path> (Do NOT Modify)
This value specifies the path of the service executable.

Start

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Start
Name Type Default Data
Start REG_DWORD 2 (Do NOT Modify)
This value specifies when the service loads. For the SIOS DataKeeper service, this value must be set to 2, allowing the service to start automatically during system startup. Setting this value to anything else may result in a system crash or cause disk corruption.

Type

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirrSvc\Type
Name Type Default Data
Type REG_DWORD 16 (0×10) (Do NOT Modify)

_____________________________________________________________

HKEY_LOCAL_MACHINE\SYSTEM

\CurrentControlSet

\Services

\ExtMirrSvc

This key is the base key for the driver. All values directly under this key are used by the operating system to load the driver. These should not be modified or else the driver may not load correctly. The driver does not use these values internally. More information on these specific keys can be obtained in the regentry.hlp file in the Windows Resource Kit.

ErrorControl

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\ErrorControl
Name Type Default Data
ErrorControl REG_DWORD 1 (Do NOT Modify)
This value specifies what the system should do in the event the driver fails to load. The default value of 1 tells the system to ignore the failure and continue booting the system. Changing this value may prevent the system from starting.

Group

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Group
Name Type Default Data
Group REG_SZ Filter (Do NOT Modify)
This value specifies the name of the group in which the SIOS DataKeeper driver is a part of. This value should always be Filter. Changing this value could result in unpredictable results, including disk corruption.

Start

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Start
Name Type Default Data
Start REG_DWORD 0 (Do NOT Modify)
This value specifies when the driver loads. For the SIOS DataKeeper driver, this value must be set to 0, allowing the driver to start during the initial phase of system boot. Setting this value to anything else may result in a system crash or cause disk corruption.

Tag

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Tag
Name Type Default Data
Tag REG_DWORD 0×4 (Do NOT Modify)
This value specifies the order in which a driver loads in its group. For the SIOS DataKeeper driver, this value should be 0×4 specifying that the driver will load at the same time as DiskPerf.Sys, which is right above FtDisk.Sys (NT’s Fault Tolerant disk driver) and below the file systems. Changing this value may cause disk corruption.

Type

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Type
Name Type Default Data
Type REG_DWORD 0×1 (Do NOT Modify)
This value specifies the type of executable this key defines. For the SIOS DataKeeper driver, this value should be 0×1 specifying that it is a kernel mode driver. Changing this value will have unpredictable results.

_____________________________________________________________

HKEY_LOCAL_MACHINE\SYSTEM

\CurrentControlSet

\Services

\ExtMirrSvc

\Parameters

The SIOS DataKeeper driver uses this key and those below it. The values below this are used internally by the driver. The values directly under the Parameters key represent values that are global for all volumes on the system.

BuildDate

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\BuildDate
Name Type Default Data
BuildDate REG_SZ <None> (Do NOT Modify)
Specifies the date that the driver was built.

BuildTime

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\BuildTime
Name Type Default Data
BuildTime REG_SZ <None> (Do NOT Modify)
Specifies the time that the driver was built.

LastStartTime

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\LastStartTime
Name Type Default Data
LastStartTime REG_DWORD 0 to MAX_DWORD (Do NOT Modify)
This value specifies the time, represented as seconds since January 1, 1970 in Greenwich Mean Time (GMT), since the system was started with the SIOS DataKeeper driver running. This value is written to the registry during driver initialization and never read by the driver. This value is currently for informational purposes only.

Version

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Version
Name Type Default Data
Version REG_SZ <None> (Do NOT Modify)

Specifies a text string containing the version number of the last SIOS DataKeeper driver to have booted on this system.

Note: Any changes in the following values will take effect after the next system reboot.

_____________________________________________________________

HKEY_LOCAL_MACHINE\SYSTEM

\CurrentControlSet

\Services

\ExtMirr

\Parameters

\Volumes

\{Volume GUID}

Keys under the Parameters\Volumes key represent disk volumes that have been mirrored (either Source or Target). The key name represents the GUID that Windows assigns to the volume in the Disk Management program.

Failover

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Failover
Name Type Default Data
Failover REG_BINARY 1 (Do NOT Modify)
Specifies whether the mirror is becoming a target due to failover. Used internally by the driver.

MirrorRole

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\MirrorRole
Name Type Default Data
MirrorRole REG_DWORD 0 (None), 1 (Source), 2 (Target) (Do NOT Modify)
Specifies the mirroring role of the volume. Used internally by the driver.

SnapshotDevice

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\SnapshotDevice
Name Type Default Data
SnapshotDevice REG_SZ \\.\PHYSICALDRIVE<x> (Do NOT Modify)
Specifies the virtual disk attached for target snapshot. Used internally by the driver.

VolumeAttributes

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\VolumeAttributes
Name Type Default Data
VolumeAttributes REG_DWORD 0 (Do NOT Modify)

Specifies a bitmap of the volume attributes set by the SIOS DataKeeper Service. Used internally by the service and the driver.

BIT 0: All Net Alert

BIT 2: Resync Done Alert

BIT 3: FailOver Alert

BIT 4: Net Failure Alert

BIT 5: LifeKeeper Configured

BIT 6: Auto Resync Disabled

_____________________________________________________________

HKEY_LOCAL_MACHINE\SYSTEM

\CurrentControlSet

\Services

\ExtMirr

\Parameters

\Volumes

\{Volume GUID}

\Targets

\{Target IP}

Note: The following fields are present under the <Target Name> subdirectory on the source and under the &;t;Targets> subdirectory on the target.

Below is a list of registry values that define the configuration for each volume:

BitmapFileEnabled

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\BitmapFileEnabled
Name Type Default Data
BitmapFileEnabled REG_BINARY 1 (Do NOT Modify)
Specifies whether a bitmap file will be created for a mirror. The bitmap file makes it possible for a mirror to recover from a primary system failure without a full resync.

BitmapFileValid

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\BitmapFileValid
Name Type Default Data
BitmapFileValid REG_BINARY 1 (Do NOT Modify)
Bitmap file contains accurate changed block information.

Enabled

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\Enabled
Name Type Default Data
Enabled REG_BINARY 1 (Do NOT Modify)
Indicates the mirror exists.

TargetDriveLetter

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\TargetDriveLetter
Name Type Default Data
TargetDriveLetter REG_BINARY None (Do NOT Modify)

Specifies the drive letter of the volume on the target side at the time of a mirror creation or continue. This value is the Unicode representation of the drive letter.

This value is written by the driver during a mirror creation or continue operation and is present for informational purposes only. The driver does not read this value.

Note: It is possible for drive letters to change while the system is running. This can be done by using the Disk Management utility and other methods. This value is only accurate as of the last mirror create or continuation.

WARNING: THIS VALUE SHOULD NOT BE CHANGED BY THE USER.

SourceDriveLetter

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\SourceDriveLetter
Name Type Default Data
SourceDriveLetter REG_BINARY None (Do NOT Modify)

Specifies the drive letter of the volume on the source side at the time of a mirror creation or continue. This value is the Unicode representation of the drive letter.

This value is written by the driver during a mirror creation or continue operation and is present for informational purposes only. The driver does not read this value.

Note: It is possible for drive letters to change while the system is running. This can be done by using the Disk Management program and other methods. This value is only accurate as of the last mirror create or continuation.

WARNING: THIS VALUE SHOULD NOT BE CHANGED BY THE USER.

MirrorState

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\MirrorState
Name Type Data Default
MirrorState REG_DWORD Range:
0 (None), 1 (Mirror), 2 (Resync),
3 (Broken), 4 (Mirror Paused),
5 (Resync Pending)
0 (None) (Do NOT Modify)

Indicates the current mirroring state of a volume.

WARNING: THIS VALUE SHOULD NOT BE CHANGED BY THE USER.

MirrorType

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\MirrorType
Name Type Data Default
MirrorType REG_DWORD Range:
0 (None), 1 (Synchronous),
2 (Asynchronous)
0 (None) (Do NOT Modify)

Indicates the type of mirroring this volume is engaged in.

WARNING: THIS VALUE SHOULD NOT BE CHANGED BY THE USER.

CleanShutdown

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\CleanShutdown
Name Type Default Data
CleanShutdown REG_DWORD 1 (Do NOT Modify)
Indicates whether reboot was intentional or the result of a failure.

BreakUserRequested

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\BreakUserRequested
Name Type Default Data
BreakUserRequested REG_BINARY None (Do NOT Modify)

Determines whether the mirror was broken or paused because of an error or because the user requested the break/pause. If this entry indicates a break error, the system attempts to recover from the break/pause.

Note: This entry is used internally by the SIOS DataKeeper driver.

RemoteName

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ExtMirr\Parameters\Volumes\{Volume GUID}\Targets\TargetIP\RemoteName
Name Type Default Data
RemoteName REG_SZ None (Do NOT Modify)
Indicates the name of the system (string value) that we are mirroring with. This value on the target indicates the source; this value on the source indicates the target.

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