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Document ID:1552
Subject:Can I use Syncrify to backup to a local drive on the machine
Creation date:10/20/10 10:17 AM
Last modified on:10/20/10 11:25 AM


Backing up to a local drive


Often users ask us if they can use DeltaCopy and/or Syncrify to backup to a local drive, such as a USB drive or a different hard drive on the local machine.

While this is certainly possible, it is NOT recommended. Imagine you want to go from New York's JFK airport to LaGuardia (or from Heathrow to Gatwick if you live in London) and someone rolls out a Boeing 747 - there are better alternatives.

The rsync algorithm (used in DeltaCopy as well as Syncrify) is designed to minimize network traffic at the cost of local disk I/O and CPU. Keep in mind that the rsync algorithm spends some time to figure out the part of file that has changed, called delta, and then merges it to the target file. Since a network is not involved when copying files between local disks, it is more time consuming to figure out the delta than to copy the entire file again.

Alternate Solution

Nothing can be faster than using the native file copy commands provided by the operating system. Consider the following solution when copying files between local drives (these steps assume you are working on MS Windows platform)
  • Assume you want to backup C:\ImportantData folder to F:\ImportantData
  • Create a Windows batch file with the following command
    xcopy C:\ImportantData F:\ImportantData\ /D /S /Y
    The /D attribute in the command ensures you only copy newer files from source to target, skipping files that match.

  • Optionally, create a scheduled task using Windows Task Scheduler to run this batch file automatically based on a schedule.


If you insist

For any reason, if you want to Syncrify/DeltaCopy in this scenario, you will have to install both server and client piece on the same machine and treat it as if you are going over the network.

Exceptions

There are always exceptions to this rule. For example:
  • Encryption -You want to encrypt the files on the target drive.
  • Versioning - You want to maintain multiple versions of a file and want to save disk space by only storing file deltas.

The moral of the Story

Consider using DeltaCopy and/or Syncrify when copying files across the network and use local file copy mechanisms when copying files to a local disk.



User comments

Posted by Richard Stevem Hack on 3/20/11 3:32 AM

I agree with Michael. My client's application for this product would be backing up multiple video files which are dozens of gigabytes in size every night. Having a strictly incremental backup approach that only moves changed bytes would be useful. If this can't be done efficiently for local backups, then, like Vembu's Storegrid which has the same problem, then we'll have to look elsewhere.

Posted by Michael on 10/25/10 2:52 PM

Those of us dealing with large files with just a few bytes changing between backups, such as vmware disk images, cannot use xcopy because it would copy entire files when only a few bytes change and quickly exhaust backup space. By contrast, Syncrify, taking advantage of rsync's checksum-based differencing, minimizes the use of backup space, it's a very efficient way to store lots of versions of vmware disk images. And the only backup product that can do this, other than complex version-control software aimed at developers. Additionally, the bottleneck for modern computers is not CPU power, but it's disk access, making Syncrify faster than xcopy with the /D switch when backing up vmware disk images or other large files with few bytes changing between backups. If it's not too much work to completely remove the networking overhead and produce a version that does the rsync checksums and cutting up offline, you have a winner.

Posted by Ed Sullivan on 9/26/11 3:25 PM

Copying the delta to a local drive is better for files such at Outlook.pst. If Syncrify is using CPU for backing up to remote storage, then there would be little more overhead to copy the backup to a local drive as well as to remote storage. Surely having two backups (including your versions) in two different locations is basic good practice? Surprised an otherwise good backup software doesn't seem to support this. Anyone know of a product which will backup (incl versions) to a local drive and remote storage?

Posted by Kenneth Dunning on 10/20/10 11:10 AM

Using the /E switch rather than /S will get you any empty folders as well. Helpful if you are a software developer and want to retain structure. Cheers!


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