If a Time Machine backup takes longer than you expect

It might take longer to perform a Time Machine backup if many files have changed or your previous backup was interrupted.

You can use the Time Machine menu to check the progress of your backup. When Time Machine backs up your data, the "Backing Up" indicator appears and increments:

If you see an alert message in the Time Machine menu, or you can't back up at all, see "If you can't back up or restore your Mac using Time Machine." 

If your Time Machine backup is working but it takes longer than you expect, check these things:

Your first backup

The first time you back up your Mac with Time Machine, it might take a long time to complete. This is because Time Machine copies most or all of the data on your Mac to your first backup. You can keep using your Mac while Time Machine works in the background to back up your data. 

After the first backup is complete, Time Machine works in the background to back up only files that have changed since your last backup. This means your next backup is usually faster.

If you want to pause a backup and finish it later, select the option to Skip This Backup from the Time Machine menu. Time Machine automatically tries backing up again later. If you want to start a backup manually (like overnight) choose Back Up Now from the menu to start it. 

Backing up large changes

Some backups might take longer than others if you've made changes to a lot of files, or changes to large files since the last time you backed up. You might see "Preparing" in the Time Machine menu for a longer period of time when this happens. For example:

  • When your backup disk isn't available (like when you're traveling, or your backup disk is disconnected or powered off) Time Machine can't back up your files. If you use your Mac for several days without access to your backup drive, it might take longer the next time the drive is available.
  • If you have a virtual machine set up on your computer like Parallels or VMWare, this software might create a large disk image (or a similar file) to store data related to other operating systems. Time Machine might try to back up the whole disk image, even if you've only changed a few files on it. For best results, make sure your software is up to date, then check the developer's support site for information on using Time Machine with these apps. If you want Time Machine to skip these files, you can also tell Time Machine to exclude them from your backup.
  • If you recently installed new software or upgraded OS X, it might take longer to complete the next backup. After Time Machine finishes backing up your new software, backups should happen faster. 
  • If you cancelled or unexpectedly interrupted the previous backup, Time Machine might take longer the next time it backs up your files. This can also happen if you don't shut down your Mac properly, or if you don't eject a drive before disconnecting it.

Network speed

If you're backing up over a Wi-Fi network, make sure your Wi-Fi access point or router is nearby. A Wi-Fi network connection can slow down if your Mac is too far away from your router. You can get a good idea of how strong your wireless network signal is by looking at the Wi-Fi menu.

Network issues can also impact the performance of backups. If backing up over Wi-Fi seems slow, check for wireless interference or network congestion.

Anti-Virus software

If you use anti-virus software on your Mac, make sure this software is up to date. If it appears to interfere with backing up your computer, you might want to exclude your backup drive from being virus scanned. Check the documentation that came with your anti-virus utility or contact the maker of the utility for more information.

Check your drives

Your backup might be slower if there's an issue with one of the drives you're backing up, or with the drive where your backup is stored. 

AirPort Time Capsule

AirPort Time Capsule automatically verifies its built-in disk when you turn it off and back on again.

  1. Disconnect your AirPort Time Capsule from AC power.
  2. Wait ten seconds, then reconnect your AirPort Time Capsule to power.

When the built-in drive on your Time Capsule is working, the light turns green. If your Time Capsule finds an issue, the light on the Time Capsule continually flashes amber. Open AirPort Utility and connect to your Time Capsule to learn more about the issue.

If your Time Capsule finds an issue with its built-in drive, you might need to erase it. Create an additional backup of your data using Time Machine and another drive. Then try erasing the drive in your Time Capsule using AirPort Utility. If you're unable to erase the drive, your Time Capsule might need service.

Other drives

Use Disk Utility to verify your startup disk, external backup drives, and other drives you are trying to back up.

  1. From the Apple menu, choose System Preferences.
  2. From the View menu, choose Time Machine.
  3. Set Time Machine to Off to disable Time Machine backups.
  4. Connect your backup drive to your Mac.
  5. Open Disk Utility located in /Applications/Utilities.
  6. In Disk Utility, locate and select the drive you want to check in the sidebar.
  7. Click Verify Disk, or click Repair Disk.

You can turn Time Machine back on after your drives are verified or repaired successfully.

If Disk Utility indicates that you need to repair your startup disk, start your Mac from OS X Recovery or safe mode. If Disk Utility finds issues it can't repair with one of your disks, see "Using Disk Utility to verify or repair disks" for more information on the next steps to try.

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