Skip to main content
CrashPlan Support

Real-Time Backup For Network-Attached Storage

Applies to:
  • CrashPlan for Home


CrashPlan for Home supports real-time backup on directly connected drives, but not real-time backup on network-attached drives. This article provides some suggestions from users who have resolved issues with this unsupported configuration.

Unsupported Process
The information presented here is intended to offer information to advanced users. However, Code42 does not design or test products for the use described here. This information is presented because of user requests.

Our Customer Champions cannot assist you with unsupported processes, so you assume all risk of unintended behavior. You may want to search our support forum for information from other users.

Before you begin

Review the following recommended settings within the CrashPlan app to ensure continuous backup.

  • In Settings > General:
    • When user is present, use up to must be set to a value greater than zero.
  • In Settings > Backup:
    • Set Backup will run to Always.
    • In Advanced settings > Configure, select Watch file system in real-time.
    • In Frequency and versions > Configure, set your Backup frequency setting to the default, 15 minutes.

Recommended solution


Windows doesn't notify CrashPlan about changes on network-attached disks. Changes on network disks are only detected when CrashPlan scans the backup file selection. You can configure how frequently the selection is verified from Settings > Backup.

Recommended Backup Frequency Settings
We recommend setting your Backup Frequency to the default of 15 minutes or longer. If you set the CrashPlan app's frequency to a shorter interval, your backup performance can be significantly slower or your backup may never complete.

OS X and Macos

The CrashPlan app depends on Spotlight to tell it when new files are created or existing files are changed.

In some versions of OS X and macOS, Spotlight does not index network-attached drives. This means Spotlight isn't telling the CrashPlan app that files have changed. As a result, the CrashPlan app does not back up changes until the file verification scan (which runs daily by default).


If you are backing up an account protected with FileVault, you must install the CrashPlan app per user for use with FileVault.


If the CrashPlan app isn't backing up real-time changes on your network-attached drive, Spotlight isn't indexing the drive. The CrashPlan app backs up changes during its file verification scan (which runs daily by default), but it does not back up real-time changes.

You can use the Terminal command mdutil to control Spotlight's indexing or schedule a reindexing. Depending on the size of the files being indexed, Spotlight's indexing may take several hours.

  • To enable Spotlight indexing:
    sudo mdutil -i on <volume_name>
  • To trigger a Spotlight reindex:
    sudo mdutil -E <volume_name>


The CrashPlan app on Linux depends on the inotify kernel module to know when files are added or edited in real-time.

If real-time backup issues continue after inotify is installed, you may need to increase the number of watches that can be created. The inotify module is governed by a property called max_user_watches. By default, inotify provides 8192 watches, which is often too low for large file selections.

If you have more files, directories, or other file system elements than the maximum number of inotify watches, real-time backups will not apply to further files and the following error appears in the CrashPlan app's engine_error.log:

inotify_add_watch: No space left on device
  • To temporarily change your inotify watch limit, run a command like the following (where the watch limit is set to 1048576):
    echo 1048576 > sudo /proc/sys/fs/inotify/max_user_watches
  • To permanently change your inotify watch limit, modify the fs.inotify.max_user_watches values in /etc/sysctl.conf and restart:
    sysctl -p