• GBM is designed so that the client software installed on the device does all the ‘heavy lifting’ required for backups. Nothing is done server-side, it is all client-side. This means that if the client device is constrained in any way by resources (low-power CPU, minimal RAM, low-quality LAN or switching equipment, slow internet speeds, etc), then this may have a harmful effect on the speed of any backups.


  • Solution: 
    • Troubleshoot any network or hardware issues as applicable; or
    • Check for other backups or other activity which may be overloading the LAN or the internet around the time of the slow backup.



Slow backup jobs 


There are many possible reasons why a backup job might be slow.


Recent changes 

Did the issue suddenly start happening, on a certain time?

  • New software
    • Any recently-installed software might change the performance profile of the customer's PC.
    • On Windows, check in "Programs And Features" and sort by Date to see any recently-installed software
    • Does the issue coincide with a GBM software update?


Customer PC performance 

  • Antivirus

    • Many antivirus programs will scan each file as GBm reads them, including but not limited to ESET NOD32 and Windows Defender.
    • Does it help to exclude GBM's backup-tool.exe program in the antivirus software?
      • GBM 19.3.13 and later automatically does this for Windows Defender.
    • Does the antivirus process show as having high usage in Task Manager when the backup is running?

  • Use of slow settings

    • Ensure the "Limit backup to use only 1 disk thread" option is not enabled
    • Ensure the "speed limit" option is not enabled
    • Ensure the "Prefer temporary files instead of RAM (slower)" option is not enabled
    • Toggle the "Rescan unchanged files" option, to see if it increases- or decreases- performance

  • RAM usage

    • With large (multi-TB) Storage Vaults, there are many different data chunks that could be deduplicated against. GBM will start to use a few GB of RAM to hold all the indexes for deduplication. If the local PC is low on RAM, it may use the swapfile / pagefile, that can significantly reduce performance.

  • CPU usage

    • Comet compresses and encrypts all data before upload. On weak CPUs this may cause high CPU usage. The CPU usage may become a bottleneck.

Storage performance 

Check what kind of disks the customer is backing up.

Check what kind of storage the customer is using.

Check where the temporary directory is for the backup service user account.

  • Avoid backing up files from a network share

    • If you are backing up files from a network location, GBM must make many network roundtrips to access the data. It may be substantially faster to install GBM on the network device instead.

  • Backup storage on the same volume as the backup source

    • Using a mechanical harddrive for multiple tasks simultaneously may reduce its performance from the sequential-level down to the random-level, even for sequential tasks.

  • Backup source is a single-queue block device

    • GBM issues many requests to the source disk in parallel. To avoid negatively affecting other programs on the PC, GBM tries to access the source disk at a low OS priority, but this may be ineffectual if your disk only supports a single queue. You can toggle the "Limit backup to use only 1 disk thread" option to force GBM to make only a disk request to the source disk at a time. This may have a positive effect on other programs on the PC, at the expense of backup job performance.

  • Use of external harddrives

    • Is it USB 2 or USB 3?
    • Some disk drives may experience slow performance. You can use a benchmarking tool to determine the expected performance of the USB drive  both in sequential reads, and in small random reads) independently of Comet, as a baseline to compare against GBM's performance.
      • At the time of writing, CrystalDiskMark is a popular freeware software for measuring disk performance on Windows.
    • Performance Mode
      • There is an option in Windows to control whether USB drives are configured for "Quick removal" (default) or "Better performance". Switching to the latter mode can significantly improve performance, but requires you to safely eject the drive. To change this setting:
        1. Open Device Manager > Disk drives > Properties > Policies tab
        2. If the "Quick removal" / "Better performance" radio option is available, ensure it is set to "Better performance"
        3. If the "Enable write caching" checkbox option is available