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During the imaging process, the data transfer rate is specified in Mbits/sec. The transfer rate will always be lower than the link speed, sometimes significantly. This is due to communication overhead, contention (i.e. shared use of the link) and CPU bottlenecks.

For backups to a USB 2 and firewire connected external hard disk, you can expect ~ 200Mbits/sec (1GB per minute).

 

For backups to a USB 3, you can expect somewhat more than 200Mbits/sec. It will typically be limited by the performance of the hard disk or firmware.

It is difficult to estimate the expected rate for backups over 100Mbit/1Gbit as it will depend on how saturated the network is and the performance of the network attached storage.

Note that the data rate might vary considerably due to variable compression rates, link contention etc.

 

If you are getting very much less than these rates, then it is indicative of a issue.

Note that setting the 'intelligent sector copy' and differential and incremental imaging will greatly improve backup times.

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Potential causes of poor performance

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Confirm that you are running the latest revision of Reflect. Recent revisions have included enhancements that will improve performance for some users. Also, backup performance reporting is now included (see below).

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Techniques to isolate the source of the problem

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As of release v5.1.5732, the i/o performance is reported at the end of the log file for a backup. This will give you some further insight into what may be the bottleneck in the case of poor backup performance. As previously noted, these figures will always be less than the SATA/ethernet theoretical data rates.

1. If the read performance is significantly less than the write speed, the bottleneck is the source disk, interface etc.
2. If the write performance is significantly less than the read performance, then the bottleneck is with storing the image files.

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Tuning options

Direct disk writing 

If you still haven't identified the source of your issue, then it might be a due to a flawed driver that performs poorly with direct disk writing. You can disable it as follows.
From the other tasks menu, pick edit defaults, click on the Advanced icon and pick "Advanced Backup options" from the left.
Check "Enable write file caching".
Image Removed
 by using the 'Disk Write Performance' dialog.  

Image Added

See here for more information: Disk Write Performance dialog 

 Write buffer size

In very rare cases it could be a problem with the write buffer size. This is basically the size of each 'chunk' of data that's written (or sent over the network). You should never normally need to alter this, and doing so will normally reduce your imaging performance. Proceed with great care.

The default size is 4MB but you can modify it by creating the following registry key:

Code Block
language text
Key: HKEY_CURRENT_USER\Software\Macrium\Reflect\VSS Name: WriteBuffer Type: DWORD Value: 4096

 

The value is in KB so 4096 is 4MB. Try it to a lower value to see what impact that has on the network speed. If the impact is negligible or negative, restore the original value.

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Hard drives can possibly be put into sleep mode by system settings. To change power options for drives:

1. Open Control Panel > Power Options (this can be found under System & Security for Windows Vista onward).
2. Select 'Change plan settings' for whichever plan you currently have configured (a link on the right hand side of the selected power option).
3. Click 'Change advanced power settings'.
4. Select 'Hard Disk' > 'Turn off hard disk after'. Set a value of 1 hour or more. Having this value too low (less than a minute for example) could cause a hard disk to go into low power/suspend mode during a backup. This will adversely affect backup performance and the lifetime of the disk.

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