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Changing the Write Throttle Queued File Parameter XenData Technical Note XTN805 October 7, 2008 Copyright 2008 XenData Limited. All rights reserved. Overview: With the default settings, a XenData Archive Series system will throttle the writing of files to the archive when there are 10 files on the disk cache that are waiting to be saved to a Volume Set. This technical note describes how to change the number of queued files before throttling from the default value of 10. Changing the Queued File Parameter 1. Ensure that the archive system is idle and stop the XenData Archive Series service. 2. Edit the XenDataState.xml file which is located in the C:\WINDOWS\system32 folder as described below. 3. Restart the XenData Archive Series service Edit Instructions A typical XenDataState.xml file without any adjustment for the queued file parameter is shown below:
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<VolumeSet Identity="486ABCAC-00000000"
Name="486ABCAC-00000000"
MediumType="Tape"
Attribute="Unknown"
Replicas="1"
Compressed="0"
Deferred="0"
GroupedReplicas="0"
UnusedCapacity="0.02"
NewVolumeCapacity="0.95">
<Backup
Immediate="0"
Periodic="0"
Volume="0"
Timed="0"
/>
</VolumeSet>
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<VolumeSet Identity="486ABCAC-00000004"
Name="486ABCAC-00000004"
MediumType="Tape"
Attribute="Rewritable"
Replicas="1"
Compressed="0"
Deferred="0"
GroupedReplicas="0"
UnusedCapacity="0.02"
NewVolumeCapacity="0.95">
<Backup
Immediate="0"
Periodic="0"
Volume="0"
Timed="0"
/>
<State
Name="finalised"
/>
<FileSystem
FileSystemType="Tape"
/>
<Medium
Identity="Barcode:X0003BL4"
MediumType="Tape"
Attribute="838026133504
byte Rewritable"
WriteProtected="0"
Replica="0"
BlockSize="512"
Compressed="0"
NumBlocks="1636769792"
LastWrittenBlock="1598032502"
Overhead="7490954"
Compression="0"
Manufacturer="MAXELL"
SerialNumber="1110775888"
Date="20070915"
MountCycles="207"
/>
</MediaSet>
</Volume>
</VolumeSet>
</VolumeSetSet>
<FileGroup
Name="Default"
Path="*"
Flags="3"
FragmentSize="0"
ReadRetentionTime="0"
WriteRetentionTime="0"
VolumeSet="486ABCAC-00000000"
/>
</FileGroupSet>
</FileGroupSetSet>
<Interface
Identity="0"
MountPoint="X:"
FileGroupSet="0"
/>
</InterfaceSet>
<BlankMediaSet
/>
<CleaningCartridges
/>
</CleaningCartridges>
<Medium
Identity="Barcode:LTO0036B"
MediumType="Tape"
Attribute="419105341440
byte Rewritable"
WriteProtected="0"
Replica="0"
BlockSize="512"
Compressed="0"
NumBlocks="818565120"
LastWrittenBlock="0"
Overhead="0"
Compression="0"
Manufacturer="MAXELL"
SerialNumber="2110318568"
Date="20061125"
MountCycles="878"
Status="Time:0x48EBE0AB
InternalError:0xC00007FF 0:"TapeDrive.cpp" 1:"2304"
2:"Barcode:LTO0036B"" />
<Medium
Identity="Barcode:A0000173"
MediumType="Tape"
Attribute="419105341440
byte Rewritable"
WriteProtected="0"
Replica="0"
BlockSize="512"
Compressed="0"
NumBlocks="818565120"
LastWrittenBlock="0"
Overhead="0"
Compression="0"
Manufacturer="MAXELL"
SerialNumber="1170694392"
Date="20070315"
MountCycles="863"
Status="Time:0x48EBE106
InternalError:0xC00007FF 0:"TapeDrive.cpp" 1:"2304"
2:"Barcode:A0000173"" />
<Medium
Identity="Barcode:LTO0043B"
MediumType="Tape"
Attribute="419105341440
byte Rewritable"
WriteProtected="0"
Replica="0"
BlockSize="512"
Compressed="0"
NumBlocks="818565120"
LastWrittenBlock="0"
Overhead="0"
Compression="0"
Manufacturer="MAXELL"
SerialNumber="2200271331"
Date="20061125"
MountCycles="513"
Status="Time:0x48EBE166
InternalError:0xC00007FF 0:"TapeDrive.cpp" 1:"2304"
2:"Barcode:LTO0043B"" />
</QuarantinedMedia>
</QuarantinedMedia>
<Options
TransferSize="256"
EnablePadding="0"
BackupFlushInterval="30"
BackupFileSize="1048576"
HSMCachedObjects="1024"
DriveHoldTime="500"
ExportBusyHoldTime="5000"
IdleDismountTime="600000"
/>
</XenDataState>
The last portion of the XML file should be edited as shown below to change the queued file parameter. In this example it has been set to a value of 20 :
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<Options TransferSize="256"
EnablePadding="0"
BackupFlushInterval="30"
BackupFileSize="1048576"
HSMCachedObjects="1024"
DriveHoldTime="500"
ExportBusyHoldTime="5000"
IdleDismountTime="600000">
<WriteThrottle
QueuedWrites="20"
FixedDelay="0"
DelayPerRequest="0"
DelayPerMegabyte="0.002"
/>
</Options>
</XenDataState>
The WriteThrottle QueuedWrites= parameter determines the number of files on the disk cache that are waiting to be saved to a Volume Set before write throttling occurs. Note that the edit involves removing the '/' after the IdleDismountTime="600000" parameter and adding two additional lines.
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