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Synchronizer Document Fundamentals

























ChronoSync is a document-based application. This means that to create a backup or synchronization task, you create a synchronizer document to define that task. This document, much like a word processing or spreadsheet document, contains all the settings that define the task. The source, the destination, the type of operation to perform and a myriad of options are all stored within the synchronizer document. To perform a specific task, you open the desired synchronizer document that you created and then you run the document. Alternatively you can open the desired synchronizer document and schedule it to run automatically at an interval of your choosing.

The advantages of the document-based approach are numerous. The most obvious advantage is that, once configured, you can re-use a synchronizer document over and over again without having to re-specify its settings. More significantly, but perhaps not so obvious, is that the document-based approach offers fine-grain control over your synchronization and backups. You can create as many or as few synchronizer documents as desired. The scope of a synchronizer document can be a single folder with just a few files or an entire hard drive with millions of files. Multiple synchronizer documents can specify the same source for a backup operation but different destinations. Synchronizer documents can be chained so that the output of one is the input for another. Multiple synchronizer documents can also be combined in a single container document and behave like a single document — the possibilities are truly limitless.

Note: This guide takes you through the steps of how to perform a simple backup to an external drive. If you are doing this with a newly purchased external hard drive, you may need to give consideration to reformatting the drive first. Take a look at our Formatting and Partitioning Hard Drives guide for instructions on how to determine if a re-format is necessary and, if so, how to perform the reformatting operation.


The first step in creating a synchronization or backup task to to create a synchronizer document. Don’t let the name confuse you — whether or not this task is a synchronization or a backup, you still create a synchronizer document. A backup task is simply a synchronization performed in one direction!


To create a synchronizer document, simply launch ChronoSync — the Document Organizer window should appear. From this window click the "Create new synchronizer document" button.

Create a new document

A new synchronizer document window will open and you will be asked to supply a name. Supply something meaningful that describes the task you are about to define. For instance, if you will be backing up your entire home folder you might type a name such as "Backup My Home Folder."

Supply a meaningful filename


Your synchronizer document has now been created but it is not in a usable form since it needs to be configured. The first step in configuration should always be to choose the type of operation you want to perform. ChronoSync supports a variety of operations that can be chosen from the pop-up menu at the center of the synchronizer document editor window.

Backup Left-to-right

The choices can be somewhat daunting but it all boils down to three basic options:

Backup — Modified files & folders on the source side of the operation are copied to the destination. Any older duplicates are replaced. Existing files on the destination that are not duplicates will be left alone.

Mirror — The destination side of the operation will be made identical to the source. This means that duplicate files on the destination will be overwritten and existing files will be deleted.

Synchronize — Modified files & folders on either side of the operation will be copied to their counterpart. The result is a merge of the two sides. If there are duplicate files, the most recently modified ones will be used. This operation is chosen when files on both sides are actively being modified such as when synchronizing between a desktop computer and a laptop.

Note: for more info regarding the difference between these operations, as well as an introduction to some basic terminology, see our To Sync or Backup guide.

With the exception of "Synchronize Bidirectional", you will also need to make a direction choice e.g. left-to- right or right-to-left. This is simply a matter of preference and allows you to visualize the direction that data will flow. For example, if you have an external hard drive located on the right side of your monitor, and it will be your destination, you should choose left-to-right as the direction so you can visualize what is happening.

For this guide, we will be making a backup of the entire home folder, so we'll leave the operation at the default "Backup Left-to-right" setting.


For a backup operation, the source target is where your original files & folders are stored. It is where ChronoSync will start scanning for changes and will copy any modified files and folders over to the destination target. Don't let the term target confuse you — it does not signify a destination — it is merely a location on your hard drive that ChronoSync will pay attention to.

Since we are backing up our home folder, we must choose it as our source target. We do this by clicking the "Choose …" button in the "Source Target" pane of the synchronizer document window.

Select target

This will open up a standard file selection window.

Select file for target

Here we want to select our Home folder which, in the above screenshot, is named "mavd." Depending on how your Finder preferences are configured, you may or may not see your home folder in the list of "Favorites" at the left. If you do not see your home folder, you can always reach it by typing COMMAND-SHIFT-H on the keyboard. Once the home folder is chosen, click the "Select" button.

Now that the source of our backup operation has been chosen, we need to specify the destination. This is very similar to selecting the source. Begin by clicking "Choose…" in the "Destination Target" pane of the synchronizer document window.

Select destination target

This will open up the standard file selection window again.

Choose destination

Here we've scrolled down a bit in the sidebar and selected an external USB hard drive named "YoYo HD" attached to our computer. We could go ahead and select this hard drive as a destination but, instead, we will create a folder on it first by clicking the "New Folder" button.

Create new folder

Targeting a folder on the hard drive allows us to keep the data better organized since we may be using the hard drive to store more than just a backup of our home folder. Click "Create" to create the folder and then "Select" it in the file selection window. Our synchronizer document should now look like this:

Targets selected

The basic synchronizer document configuration is now complete and ready to run!


Everything is set to go at this point and you certainly may proceed to run your backup. However, you've probably noticed that there is a lot more to the synchronizer document than you have configured. It's true — there are a LOT of options that you can specify! ChronoSync understands that there is no one-size-fits-all configuration and thus provides the options to fit your needs. For a simple backup — which is what we are doing here — there are only a few extra options that you may want to consider, so we'll cover them here.


When enabled, this option will detect a deleted file on the source target and apply the deletion to the same files & folders on the destination target. This is what you should choose if you want your backup file set to be identical to your original file set. If enabled, however, we recommend keeping the default "Move to Archive" option under the "When deleting files" heading. This will place any deleted file in the synchronizer document's archive, allowing it to be recovered at a later date if you discover the deletion was in error.

Move files to archive


This option is also staring you in the face in the Setup Panel. When enabled, it will move any files that get replaced as a result of the backup into the synchronizer document's archive, allowing it to be recovered at a later date. This is a handy option because not all modifications to a file are improvements — archiving replacements ensures that you can get that old file back!


In the above screenshot, you may have noticed the readiness warning:

Readiness warning

Depending on how your external hard drive is configured, you may or may not see a similar warning. Ignoring ownership on a drive allows any user of your computer to have full access to the files and folders on that drive. It also allows the drive to be transported between different computers without any file ownership issues causing any problems. If this hard drive is going to be transported between computers, you definitely want to ignore ownership on the drive. Conversely, if this hard drive will be staying put and attached only to your computer, you should probably disable the ignore ownership setting.

To change this setting, switch to Finder and select the hard drive for which you want to change ownership setting on. Invoke the "Get Info" command (COMMAND-I) and look at the bottom of the info window that appears.

Ignore ownership on this volume

You will have to click the padlock icon and authenticate as an administrator before you can change the checkbox to the desired setting. For this guide, we will be leaving the ignore ownership setting ON.


At this stage, we are definitely ready to run the backup. However, there is one more step we're going to take to fine tune this backup before we run it. There are many files in the home folder that are of limited value to us, so we want to tell the synchronizer document to skip them. To do this, we're going to switch to the Analyze Panel by clicking the "Analyze" button in the sidebar.

Click Analyze in sidebar

This will display the analyze outline view, which provides an interactive preview of the synchronization or backup operation.

Analyze panel

From here we can navigate the file system hierarchy and examine exactly what ChronoSync will do when we run this backup. This is rather unexciting at this point since we're performing an initial backup and ChronoSync will copy everything to the external hard drive. Future runs of this backup will be more interesting as we pay attention to the "Status" column to see what ChronoSync wants do with any given file-pair.

What we are going to do right now is apply some exclusions. An exclusion is a rule that tells ChronoSync that a selected file-pair should be completely ignored. In this example, we want to ignore all the invisible files in our home folder and the entire Library folder. To do this we click, one-at-a-time, on the items we want to exclude while holding down the COMMAND key during each click. This expands the selection on each click. The end result looks like this:

Exclusions in Analyze panel

We then choose "Exclude" from the "Actions" menu or just click the "Exclude" icon in the toolbar:


Each excluded item will now have an "X" displayed in its "Status" column:

Excluded files

At this point you should save all the configuration settings by typing COMMAND-S or clicking the "Save" icon in the toolbar:


Now we really are ready to run this synchronizer document!


When running a synchronizer document you have two options: perform a full run or a trial run.

FULL RUN [top]

A full run, as the name implies, is a full run of the synchronization or backup operation. ChronoSync will analyze your targets and perform the necessary action on each and every file/folder it encounters, as it encounters them. To initiate a full run, click the "Synchronize" button in the toolbar:


… or switch back to the Setup Panel and click the big circular button beneath the "Operation" popup menu.

Synchronize now

After a brief pause, a progress sheet window will drop down showing the progress of the backup operation:

Progress sheet

The first backup operation that you run will take the longest time. Every single file on the source target must be scanned and copied. The exact amount of time it will take depends on many factors: how many files are on the source target? how large are those files? how fast are your hard drives? what kind of drive interface are you using? how fast is your computer? The good news is that subsequent runs will be much faster since ChronoSync performs incremental copies — only the files that have actually changed in between runs will be copied.


A trial run makes two passes through the targets. The first pass scans all your files and folders to determine what needs to be done. Then the results of that pass are presented in the trial synchronization selector window where you can preview and override what ChronoSync wants to do with your files. You can then initiate the second pass where the synchronization is actually performed.

To initiate a trial run, click the "Trial Sync." button in the toolbar:

Trial Sync

… or switch back to the Setup Panel and hold the OPTION (aka ALT) key on the keyboard while clicking the big circular button beneath the "Operation" popup menu.

Trial Sync operation

When the first pass is complete, the trial synchronization selector window appears:

Trial Sync window

In the trial synchronization selector sheet, you can override the synchronization of specific files by unchecking them in the first column. You can also choose specific actions such as deletion instead of synchronization by selecting the item and clicking on the "Action" popup menu. You can also cancel the synchronization in its entirety if you decide you really don't want to run it at this moment.

To proceed with the synchronization, just click the "Synchronize" button at the bottom right. Since ChronoSync now knows exactly what will be synchronized, a meaningful time estimate will also be presented in the progress sheet.

Trial Sync progress sheet

Performing a trial run is a good way to preview backups and synchronizations before they are performed. They are extremely valuable in detecting problems before they become larger issues, such as the accidental deletion of a large set of files! On an initial run, however, they are less valuable since you already know that every file and folder should be copied as part of the backup operation.


One of ChronoSync's strengths is the full user interface it provides that allows you to interact with your sync and backup. Many other backup and synchronization programs provide no such thing, leaving you to rely on Finder to locate and examine your backed-up files. This section provides a few examples of how you would want to interact with your files in a synchronizer document.


ChronoSync allows you to synchronize or backup just a portion of your files through a command know as synchronize selection. The process is simple: use the Analyze Panel to peruse your files, drilling down several levels of folders if necessary. You can drill down a folder by double-clicking on it or expanding the disclosure triangle that appears to the left of the folder.

Once you have identified the subset of files & folders that you would like to synchronize or backup, select them by clicking on their name and then invoke "Synchronize->Sync. Selection" from the "Actions" menu. A handy shortcut is to right-click on the selected items (or OPTION-click if your mouse isn't setup to work that way) and then choose "Synchronize Selection" from the contextual popup menu that appears.

Synchronize Selection in Actions menu

Synchronize selection is handy when you know a specific group of files is all that has changed and you don't want to wait for the full synchronization process to complete. Also, as you can see from the screenshot, you may invoke "Trial Synchronize Selection…", too.


ChronoSync features a built-in restore tool that is a breeze to use. This is in contrast with many backup apps from other vendors that require you to perform a backup-in-reverse to recover your data. While that is a valid solution, it's really not the best or safest approach since the potential for making a mistake is high — and that can cause more problems than it aims to solve.

To begin restoring lost files, launch ChronoSync and open the "Backup My Home Folder" document we've been working with. When the document window is open, switch to the Analyze Panel and navigate down to the folder containing the files you'd like to restore. You can drill down a folder by double-clicking on it or expanding the disclosure triangle that appears to the left of the folder.

Here we're going to perform a recovery of our Photos library. In this hypothetical example, we've accidentally deleted some important photos from our library.

Recover Photos library

Note: For this specific example, it is very important to make sure that the Photos app is not running when we perform the restore. Quitting the app that owns the data we are restoring is not always required but it's a good rule of thumb!

We've now located the library in the Pictures folder and you can see our local copy on the left has shrunk in size relative to the backup copy on the right. Luckily we have not run this backup yet or else the backup copy would have been replaced by the local copy! To restore, we simply select the library file and choose "Restore->From Right…" in the "Actions" menu, or just right-click (OPTION-click) the selected entry.

Restore from right

Invoking "Restore->From Right…" brings up the Restore Options sheet window.

Restore from destination

We've selected the "Restore only items synchronized by this document" and "Replace existing items" options. We did not enable "only if replacing with a newer/older version" since we know we want to replace the library no matter what. Clicking the "Restore" button performs the restore operation and our Photos library is now back the way we want it!

Note: you can select entire folders containing many sub-folders for the Restore operation — it is not limited to a single file!


The simple Restore example above is all well and good but what if we HAD run the backup after making our mass photo deletion and the modified library DID make its way over to the backup drive? Our hearts sink as we look at the Photos library in the Analyze Panel and they are exactly the same — there's nothing to restore from!

Archive panel

Never fear — archiving is here! Because we enabled "Archive replaced files" when configuring this backup, an archived copy of the library should exist. Switch to the Archive Panel by clicking "Archive" on the synchronizer document's sidebar.

Comparing files in Analyze

We can then navigate down the folder hierarchy looking for our Photos library.

Archive panel

Here we've located five versions of the library. The version numbers increase sequentially, so "v0005" is the latest one added to the archive. The "Archived" timestamp confirms this. The "Modified" timestamp shows when the contents of the library were last changed by the user, before it was ever added to the archive. Given all this info (and the telltale sign of the size going down by 200 MB), we've determined that the last version that contains the photos we deleted is "v0004."

Restoring this library is similar to performing the same operation in the Analyze Panel — simply select it and choose "Restore -> From Archive…" in the "Actions" menu, or just right-click (OPTION-click) the selected entry.

Restore operation

Upon invoking "Restore…", the "Restore From Archive" sheet window appears.

Restore from Archive

The first selected option, "Restore to Source Target", is what we want. This will replace our original Photos library in our home folder. If we were unsure that this really was the file we wanted to restore, we'd choose "Specific Folder." That would restore it by itself into a separate folder, allowing us to examine it safely before replacing the original.

After we click "Restore", our original library is replaced. We examine it and determine our deleted photos have returned. All is well in the universe!

Note: As in the Analyze Panel's Restore function, we could have just as easily restored a folder or batch of folders.

Note also: By default, ChronoSync will only maintain five copies of the same file in an archive. You can change this setting in the "Archive Handling" group within the Options Panel of your synchronizer document.


We live in an imperfect world and sometimes things just don’t work out as expected. If you encounter any problems working with synchronizer documents, here’s some tips that may help you get back on track:


The most likely errors you're going to encounter in a basic backup like we've created in this guide are permission errors. When you get a permission error, it simply means that you do not have permission to copy the file. It may be because you don't "own" the file or perhaps it's just because you don't have read-access to the file. This can occur even though you may be an administrator of your computer.

macOS, given its UNIX heritage, enforces ownership and access permissions on every file it manages. Most of the files that you normally access in your home folder are owned by you and you should have no problem synchronizing or backing them up. Some files, however, are created by background processes that don't respect the ownership rights in your home folder and thus you may have difficulty accessing them. When permission errors occur, there are typically three solutions:

Ignore the error — When you encounter such a file, you should ask yourself if this is really a file that you need to be synchronizing? This is especially true if it is owned by the operating system. If you choose to ignore the error, we recommend that you "Exclude" the file from synchronization so you don't see the error again. This can be done quickly and easily when ChronoSync presents the error message to you when running the synchronizer document — just click the "Exclude" button. Once excluded, that particular file will be ignored in subsequent runs.

Grant yourself access — Locate the file in question using the Finder and then use the "Get Info" command to raise the permissions of the file to the point that you can access it. If the file is not owned by you, you'll have to provide administrative authorization before doing so. Again, you should ask yourself if this really is a file you need to synchronize before doing this.

Run with Admin. Access — Click the "Connect to" popup for the target in question on the Setup Panel and choose "Local Volumes (Admin Access)." This modifies the synchronizer document so that it has full, unrestricted access to all files on any locally connected drive. This requires that you authenticate with an administrator's username and password. Note that this setting is made on a per-target basis, so you will need to apply it to both targets if you want full administrative access to each side of a sync or backup. In this guide, we've been backing up to a hard drive that is ignoring ownership, thus you would only need to make this change to the source target.


From the "Help" menu in Finder, you can try some of the following search terms (minus the quotes):



From the "Help" menu in ChronoSync, you can try some of the following search terms (minus the quotes):

"Document Organizer"


We have several video guides that show the process of creating bootable backups and restoring files.


Contact our technical support team and just ask! We don’t mind — we're here to help!