SureSync File Copy Performance is Slow

There are few settings and operating system issues that can impact file copy performance.

Hyper-V & Broadcom NICs

If any of the root paths involved in the synchronization are running as guests on a Hyper-V server, it is important to check if the host machine is running with Broadcom network interface cards (NICs). If the host has Broadcom network adapters with Virtual Machine Queue (VMQ) enabled, you will experience significantly reduced network performance depending on driver version.

This issue is outlined in the Microsoft KB article found here. Microsoft states that Broadcom has acknowledged the problem and will be releasing a driver update. The version of the driver included with Windows 2012 R2 server for the Broadcom NetXtreme Gigabit Ethernet 5720 adapter is v15.6.1.3 which still displays the problem. We have tested with version and the problem appears to be largely correct. However, our tests still show better performance with VMQ disabled. There are many machines out there running the out of date driver.

Options to address the Broadcom issue are:

  • Update the driver to the current version for your adapter model
  • Disable VMQ. To do this, launch Device Manager and expand Network Adapters. For the adapters used by the Hyper-V guest, right click and select Properties. On the Advanced tab, scroll down and click on Virtual Machine Queue. Change this setting to Disabled and apply the change. This can interrupt  network access briefly so do this during a maintenance window.

File System Fragmentation / Master File Table Fragmentation

The state of the hard drives where the SureSync root paths reside can cause performance issues. SureSync must perform frequent Master File Table (MFT) look up to find files being processed. File system or MFT fragmentation can impact performance in a significant negative manner. It is critical to be regularly defragment your hard drives to maintain optimal performance.

Commercial utilities such as Raxco's PerfectDisk offer a boot time defrag that will defrag system files including the MFT on boot. This should be performed occasionally. You can also use the Sysinternals program Contig to defrag the MFT. For example, contig c: $Mft will defrag the MFT on the C: drive of a system.

SureSync Settings

On the Rule for the Job/Relation in question, check the "Copy Security" tab as shown in the screenshot below. Any of these settings will cause a Relation to slow down somewhat because of additional processing overhead. The impact of the basic copying of permissions, auditing, and ownership is pretty minor.

The two options at the bottom of the panel named "Copy folder security objects to existing folders" and "Copy file security objects even if the file is not copied" have a substantial impact on performance because security on every single folder and file must be checked. These options should not be used except when absolutely necessary.

The Open Files tab of the Rule also contains a setting which can negatively impact performance.

The option "Allow user access to source file being copied" causes SureSync to all VSS or AOFS for each and every file which is copied. This results in a multiple second delay in copying each file. This option should only be used when absolutely necessary for your environment.

If you are using any of these performance reducing options then you should turn them off and see if performance improves. If performance does improve then you have a couple of choices:

  1. Run without the options enabled if you don't really need them turned on.
  2. Run with the options enabled if you do really need them and performance will simply remain slower.
  3. With the security setting related options you might decide to run with them off for 6 days of the week and then run with them on once a week to "catch up" any changes to security. This can be done through using multiple schedules or a monitor with intervals and a schedule depending on how the job is being run. Please contact our support team for further details.