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## SIOS DataKeeper Patch 8.10.0.1 Notes ##
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DKPatch_PW-9417-81001

Patch availability: General Availability 
Product (s) Supported: This patch is supported on SIOS DataKeeper for Windows v8.10.0

Issue(s) addressed by this patch:
1. PW-9417: Potential Data Corruption with multi-target mirrors (Sync mirrors or Async with BlockWritesOnLimitReached set)


Patch description:
This patch provides the following

1. There is a possibility of data corruption for multi-target mirrors that experience a failover during heavy write loads, if DataKeeper is blocking writes due to the mirror High Water or Byte Limit being reached.  Write blocking can happen with Synchronous mirrors, as well as Asynchronous mirrors that have the BlockWritesOnLimitReached tunable enabled.
This patch disables BlockWritesOnLimitReached behavior for all multi-target mirrors - even if the tunable is enabled for an Asynchronous mirror or if the mirror is Synchronous.  Single-target mirrors will not be affected.

This patch can be found on the SIOS FTP site at the following location:
        http://ftp.us.sios.com/pickup/DK_patches/PW-9417/v81001

To download the patch and associated files perform the following steps:
1. Visit the ftp site
2. Left-click DKPatch_PW-9417-81001.zip to download the zip file
3. Unzip the zip file, there are three files:
	- DKPatch_PW-9417-81001.exe
	- DKPatch_PW-9417-81001.md5sum
	- readme.txt
4. Verify the md5sum by running the following commands in PowerShell. Expected result is 'True'
	- cd <path to extracted files>
    - $checksum = (Get-Content .\DKPatch_PW-9417-81001.md5sum).Split(' ')[0]
    - (Get-FileHash -Algorithm MD5 .\DKPatch_PW-9417-81001.exe).Hash -like $checksum

NOTE: Alternative download methods can be used. Once the download is complete a verification of the md5sum should be performed.

Installing the exe:
NOTE: This patch will need to be installed on all servers in the cluster
To install the patch, navigate to where the patch was downloaded and double-click DKPatch_PW-9417-81001.exe to begin the installation process.

Repairing the exe:
To repair the patch, navigate to where the patch was installed and double-click DKPatch_PW-9417-81001.exe to begin the Repair process.
Select 'Repair' and apply the patch.

Uninstalling the exe:
To uninstall the patch, navigate to where the patch was installed and double-click DKPatch_PW-9417-81001.exe to begin the uninstallation process.
Select 'Revert' and apply the patch.
Once the uninstallation process is completed the original file(s) will be restored.


NOTE: After completing the install, repair, or uninstall there will need to be a mandatory reboot. If this reboot is not completed DataKeeper will not operate as expected.