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A global default option to enable Direct Disk I/O when writing to local drives.
Macrium Reflect v6, by default, uses direct disk I/O when writing to local disks. This bypasses the file system cache and may offer faster throughput of data written to the target disk in some cases. When data is written in this way it must be sector aligned, this means that each block of data written must be exact multiples of the target disk sector size, otherwise writes will fail. Because of this, the image file is closed before writing the non-sector aligned meta data and index at the end. Unfortunately this action can lead to Anti-Virus software processes exclusively locking the file for scanning and blocking the Index/Meta data write, causing backups to fail.
Release v7.0.2079 and later includes a selectable option to disable/enable Direct disk I/O.Warning Note: Deselecting this option may also have an adverse effect on backup creation times and allow AV software to interfere with the backup process. Please check your backup speeds after installing the latest release before un-checking this setting. If the option is un-checked when you install the latest release then this is due to previous configurations made in v6. We suggest that you try with this option selected/checked first.
Take 'Other Tasks' > 'Edit Defaults' > 'Advanced' > 'Advanced Backup Options':
The 'Disable Direct Disk I/O' option is selected by default and replaces the previous option 'Enable file write caching...'. The new option is broadly similar to the previous option but is enabled by default and is implemented such that, when un-checked, the same code as v6 is used to write image files.Automatically disable Changed Block Tracking on the backup target drive and selectively enable/disable CBT on any NTFS mounted drive using the Macrium Reflect UI.
The Macrium Reflect Changed Block Tracking kernel driver is very efficient and will be completely unnoticeable during normal Windows usage. Disk read speeds are unaffected and the implementation uses a sophisticated bitmap mechanism to ensure that multiple block writes to the same file cluster are only ever recorded in the change index once. If the same file cluster is written multiple times, then after the first write in the current Windows session, there is no impact. Additionally, the system 'PageFile' isn't tracked, so Windows will be working normally without noticing the CBT driver is present.
However, we have noticed an impact on image creation speeds if the backup target disk is the bottleneck in the image process. This is because the image data will be written to new file system clusters in the file and these new clusters may not yet have been used by the file system in the current Windows session. Image file data is written sequentially, as quickly as possible, and the additional overhead of maintaining a changed block index for every write can have a detrimental impact on the write speed.Info Note: If the source disk read speed and compression (if enabled) is faster than the target disk write speed then you will not have noticed any degradation in image creation time with previous releases of v7. Also, this only affects images created to local disks, Network Shares are unaffected. In our recent testing we discovered that if a fast PCIe NVMe SSD containing the source file system was imaged to a magnetic disk, connected either locally or using USB, then the image write speed was a bottleneck and the target disk showed constant 100% utilisation. When CBT was enabled on the target disk, image creation times increased by approximately 25%. It's possible that a different configuration could yield worse results and it is also possible that imaging timing times will be unaffected.
In v7.0.2079 and later, Changed Block Tracking is automatically disabled on the backup target drive when the image process starts. This means that there is no write speed impact and the transfer of data is optimal.
You can now also enable and disable CBT on any volume by using the 'Actions' menu in the main Reflect backup window:
Info Note: Please reboot after installing the latest release for the above menu option to function correctly.
The Icon on the top right of the volume display now has three states:________
No Icon
CBT is disabled on this volume. CBT can be enabled by clicking 'Actions' > 'Enable Changed Block Tracker' CBT is disabled for all volumes. CBT can be globally enabled by taking 'Other Tasks' > 'Edit Defaults' >'Advanced' > 'Advanced Incrementals and checking 'Enable Changed Block Tracking' 
CBT is enabled on this volume but no image has been created since Windows has started.
CBT is enabled on this volume and an image has been created since Window has started. The next incremental or differential image will use the Changed Block tracking index to increase image performance.
The current state of CBT for each volume can be seen by running 'MrCbtTools.exe' in the Macrium Reflect installation folder:
Example: CBT is inactive on Drive (G:) below:
If you have experience longer experienced imaging times with v7 than the same images with v6, then we suggest you try the latest release without making any changes to see if it resolves the problem.
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