When we run set-vmreplication -vmname **** -EnableWriteOrderPreservationAcrossDisks 1 we get WARNING: 'EnableWriteOrderPreservationAcrossDisks' is not required for 'Set-VMReplication'.

I can see other threads asking the exact same question I'd be about to - so is it even enabled? There's no confirmation. Checking the Technet for "Get-VMReplication" doesn't give anything obvious how to check.

As obscure as this command to enable the write order preservation is, so is the command to check which requires piping and advanced knowledge of Powershell, and no where I can find documentation how to find this info how to check.

Get-vmreplication -VMname ****** | fl enab* shows True for the server we've just ran the command on. Great.

But then curious I ran the command on each server we have utilising Replica. Result? It shows all servers as having this enabled. I've googled and looked into this and as far as I can possibly tell the default for Write Order Preservation is disabled and you are required to enable it - reading the Technet article explaining SQL support clearly says you need to enable the feature link here.

So what's the go? Is it enabled for our one server we specified? Is it enabled for all? Is the command Get-VMReplication indeed showing the correct information?

And then some bigger questions - Why is this not in the GUI? It's clearly a very important thing to have and be made clear about it's presence.

Why is it so poorly documented the use of this feature? Even where mentioned to "enable" it say in the SQL blog it gives no information if you are meant to enable it from any PC, the Hyper V host, the SQL guest etc.

What frustrates me most is no one from Microsoft will do anything with these really important questions and there'll be no clear answer to this headache of what is an essential thing apparently.

Hi Allister,

More detailed information below is for your reference:

Configuring EnableWriteOrderPreservationAcrossDisks switch
The command syntax for the switch is as follows:
Set-VMReplication -VMName <VM-Name> -EnableWriteOrderPreservationAcrossDisks 1

Note: Replace the <VM-Name> with the name of SQL Primary Virtual Machine.

There are two settings you can use with EnableWriteOrderPreservationAcrossDisks:
1 which is equivalent to True can be set to honor write order of the SQL Server application.
2 which is equivalent to False can be set to create Application-Consistent backup changes randomly

This switch is not specifically designed for SQL Server but for applications which need to override the write-order of Hyper-V Replication for Application-Consistent backup copies. This switch has nothing to do with the Standard Replica backup copies which are created for entire virtual machine.

We can set this parameter in "Set-VMReplication" and view this property by the cmdlet "Get-VMReplication", and yes, this option is unavailable in GUI by now.

Refer to:

Hosting SQL Server in Hyper-V Replica Environment

If there is anything else regarding this issue, please feel free post back.

Best Regards,

Anna Wang

• Edited by AnnaWYMicrosoft contingent staff, Moderator Wednesday, October 22, 2014 5:27 AM

Hi Allister,

More detailed information below is for your reference:

Configuring EnableWriteOrderPreservationAcrossDisks switch
The command syntax for the switch is as follows:
Set-VMReplication -VMName <VM-Name> -EnableWriteOrderPreservationAcrossDisks 1

Note: Replace the <VM-Name> with the name of SQL Primary Virtual Machine.

There are two settings you can use with EnableWriteOrderPreservationAcrossDisks:
1 which is equivalent to True can be set to honor write order of the SQL Server application.
2 which is equivalent to False can be set to create Application-Consistent backup changes randomly

This switch is not specifically designed for SQL Server but for applications which need to override the write-order of Hyper-V Replication for Application-Consistent backup copies. This switch has nothing to do with the Standard Replica backup copies which are created for entire virtual machine.

We can set this parameter in "Set-VMReplication" and view this property by the cmdlet "Get-VMReplication", and yes, this option is unavailable in GUI by now.

Refer to:

Hosting SQL Server in Hyper-V Replica Environment

If there is anything else regarding this issue, please feel free post back.

Best Regards,

Anna Wang

• Edited by AnnaWYMicrosoft contingent staff, Moderator Wednesday, October 22, 2014 5:27 AM

Hi Anna

I don't think the information that this flag has nothing to do with "Standard Replica" is correct.

http://support2.microsoft.com/kb/956893

Explains clearly:

SQL Server on Hyper-V Replica is supported provided the EnableWriteOrderPreservationAcrossDisks flag is set.

Note To set the EnableWriteOrderPreservationAcrossDisks flag, run the following cmdlet:

Set-VMReplication -VMName <vm-name> -EnableWriteOrderPreservationAcrossDisks 1

Can you also please confirm if my observation that this appears to be enabled by default anyway is correct?

I also believe Get-VMReplication needs updating with a option to simply display if Enable Write Order Preservation is enabled or not - currently requires piping and such to get the information and this process is poorly documented with Microsoft.

• Edited by Allister Wade 2 Wednesday, October 22, 2014 10:01 PM

Hi Anna

I don't think the information that this flag has nothing to do with "Standard Replica" is correct.

http://support2.microsoft.com/kb/956893

Explains clearly:

SQL Server on Hyper-V Replica is supported provided the EnableWriteOrderPreservationAcrossDisks flag is set.

Note To set the EnableWriteOrderPreservationAcrossDisks flag, run the following cmdlet:

Set-VMReplication -VMName <vm-name> -EnableWriteOrderPreservationAcrossDisks 1

Can you also please confirm if my observation that this appears to be enabled by default anyway is correct?

I also believe Get-VMReplication needs updating with a option to simply display if Enable Write Order Preservation is enabled or not - currently requires piping and such to get the information and this process is poorly documented with Microsoft.

• Edited by Allister Wade 2 Wednesday, October 22, 2014 10:01 PM

Why has this sat 6 months without an answer?

Again I am in the position of setting up a Replica for a SQL server and again am facing this warning when following Microsoft's advice of enabling the Write Order Preservation.

Again - IS THIS ENABLED BY DEFAULT?

Again - Will the "Get-VMReplication" command be updated with a simple option to display the status of the EnableWriteOrderPreservationAcrossDisks flag?

In this situation I can't remember the command to check the status, and have now no way to know if it is enabled or disabled. I have told coworkers this is a requirement based on the MS article - but yet again egg on my face when the command MS say to run doesn't even run and you have no way to know the status of this super important thing.

Again incase you cannot read everything - when I run the command that MS clearly state is absolutely required for clean SQL Replica on Hyper-V I get the following back:

WARNING: 'EnableWriteOrderPreservationAcrossDisks' is not required for 'Set-VMReplication'.

Whether I enable or disable the same warning...

WHAT THE FUCK IS GOING ON HERE???

• Edited by Allister Wade 2 3 hours 58 minutes ago

Why has this sat 6 months without an answer?

Again I am in the position of setting up a Replica for a SQL server and again am facing this warning when following Microsoft's advice of enabling the Write Order Preservation.

Again - IS THIS ENABLED BY DEFAULT?

Again - Will the "Get-VMReplication" command be updated with a simple option to display the status of the EnableWriteOrderPreservationAcrossDisks flag?

In this situation I can't remember the command to check the status, and have now no way to know if it is enabled or disabled. I have told coworkers this is a requirement based on the MS article - but yet again egg on my face when the command MS say to run doesn't even run and you have no way to know the status of this super important thing.

Again incase you cannot read everything - when I run the command that MS clearly state is absolutely required for clean SQL Replica on Hyper-V I get the following back:

WARNING: 'EnableWriteOrderPreservationAcrossDisks' is not required for 'Set-VMReplication'.

Whether I enable or disable the same warning...

WHAT THE FUCK IS GOING ON HERE???

• Edited by Allister Wade 2 3 hours 51 minutes ago

It is just information and can be safely ignored if you know what you are doing.  Follow the instructions.  Many CmdLets have warnings to let unsuspecting users know that they are altering or using a normally unnecessary setting.

When you have issues you believe to be critical you should not rely on public free forums for answers.  Call MS support.  This is not an MS Support forum or a product support forum.

You can also try using your search engine to get more information.

http://maneffa-it.blogspot.com/2013/08/enablewriteorderpreservationacrossdisks.html

One you learn how to use a search engine you will find many useful pieces of information that will save you much confusion.

Why has this sat 6 months without an answer?

Again I am in the position of setting up a Replica for a SQL server and again am facing this warning when following Microsoft's advice of enabling the Write Order Preservation.

Again - IS THIS ENABLED BY DEFAULT?

Again - Will the "Get-VMReplication" command be updated with a simple option to display the status of the EnableWriteOrderPreservationAcrossDisks flag?

In this situation I can't remember the command to check the status, and have now no way to know if it is enabled or disabled. I have told coworkers this is a requirement based on the MS article - but yet again egg on my face when the command MS say to run doesn't even run and you have no way to know the status of this super important thing.

Again incase you cannot read everything - when I run the command that MS clearly state is absolutely required for clean SQL Replica on Hyper-V I get the following back:

WARNING: 'EnableWriteOrderPreservationAcrossDisks' is not required for 'Set-VMReplication'.

Whether I enable or disable the same warning...

WHAT THE FUCK IS GOING ON HERE???

• Edited by Allister Wade 2 Wednesday, May 27, 2015 3:11 AM

Why has this sat 6 months without an answer?

Again I am in the position of setting up a Replica for a SQL server and again am facing this warning when following Microsoft's advice of enabling the Write Order Preservation.

Again - IS THIS ENABLED BY DEFAULT?

Again - Will the "Get-VMReplication" command be updated with a simple option to display the status of the EnableWriteOrderPreservationAcrossDisks flag?

In this situation I can't remember the command to check the status, and have now no way to know if it is enabled or disabled. I have told coworkers this is a requirement based on the MS article - but yet again egg on my face when the command MS say to run doesn't even run and you have no way to know the status of this super important thing.

Again incase you cannot read everything - when I run the command that MS clearly state is absolutely required for clean SQL Replica on Hyper-V I get the following back:

WARNING: 'EnableWriteOrderPreservationAcrossDisks' is not required for 'Set-VMReplication'.

Whether I enable or disable the same warning...

WHAT THE FUCK IS GOING ON HERE???

• Edited by Allister Wade 2 Wednesday, May 27, 2015 3:11 AM

jrv.

What you have written has nothing to do with answering my question and your linked article just confirmed that this should be turned on.

AGAIN... When I attempt to turn on this thing, that MS say is required, it gives that Warning and no indication if it is on or off.

After further testing since and digging up the command to actually check if it is on it appears it is being enabled on all new VM Replicas created by default.

MS clearly have mis documented this or not documented the current behaviour and they need to. Accepting this BS from MS is not OK - they should not be treating partners like this.

I don't think you understand the issue.  No one is mistreating you.  The warning makes sense.  It is a warning and not an error.  As you have noted - it is on by default.  If you feel there is some error then post in the MS Connect site or call MS support.  This forum is not a place for complaints or bug reporting.

Note that warnings can always be ignored.

Hello,

Just based on my own experiments and deployments, what I can see is that this EnableWriteOrderPreservationAcrossDisks option seems to be enabled by default when a Hyper-V Replica replication is set up on Windows Server 2012 R2 (Update 1).

I have confirmed this by running the Get-VMReplication command on all replicated VMs, and this option is set to True every time unless manually modified.

Get-VMReplication | fl *

I cannot comment for the other versions.

Kind regards

Marius