The pros and cons of backing up Windows Server 2008 to NAS

Recently we've had quite a few people ask about imaging their Server 2008 (or SBS 2008) machine to a NAS. There are a few pros and cons that we need to mention because of the specific technology with imaging and VSS.

We do have a recommended alternative that is around the same price, but delivers far better results: we recommend backing up to a locally connected USB or eSATA HDD.

For example, an entry-level WD 2TB My Book Studio II with eSATA, Firewire & USB interfaces and RAID 0/1 lists for $329 on Amazon. This is slightly cheaper than many entry level NAS devices made by Linksys, Netgear and Synology.

The following table summarizes the relative merits of each approach:

NAS Locally attached external HDD
  • Network attached – share storage across computers
  • Only one restore point per backup
  • Slower transfer speed
  • Bare metal restore requires network driver
  • Many NAS devices Linux based, don't support NTFS and can have slow processors
  • Multiple historical restore points
  • Fastest possible transfer speed (with eSATA)
  • Fast incremental backups
  • Easier bare metal restore – no need for network driver
  • True NTFS file system
  • Not network connected (but can be shared off the server)

The main difference is the number of restore points available between the two devices. Because Windows Server Backup stores past backup versions in shadow copies, and VSS is not natively available on network shares, it means that you only get one restore point when restoring from the NAS (i.e. the last backup). However, a locally attached HDD can store multiple – often tens or hundreds – of past backups, providing multiple restore points. Each past restore point is stored as a shadow copy on disk.

Backup speed can also be faster for a locally attached external hard drive when connected via eSATA, because there are no network delays or delays associated with the processor on the NAS. Some entry level NAS devices can really struggle with high loads. When connected via USB, the HDD speed will be much slower, limited by the USB interface (around 100GB/hr). (For more details, refer to our Speed Testing Cheat Sheet).

If you must use a NAS backup destination

If you must use a NAS, BackupAssist v5.2.5 has two features that we highly recommend you use!

  1. One week daily scheme: This enables you to have multiple restore points by backing up each day's backup to a different path. Choose to use the One Week Daily scheme when setting up your job, and your backups will go to different paths, such as:

    - Monday's backup - \\server\share\Monday
    - Tuesday's backup - \\server\share\Tuesday
    - Wednesday's backup - \\server\share\Wednesday
    - Thursday's backup - \\server\share\Thursday
    - Friday's backup - \\server\share\Friday

    The downside to this is that you'll need 5 times as much space on your NAS to store the last 5 backups.
  2. Delete previous backups before commencing the new one: Some NAS devices may report back an error: “Backup stopped before completing. Cannot create a file when that file already exists.” If this happens to you, in the Destination tab in BackupAssist, under Trouble-shooting options, check the checkbox to delete previous backups.

In conclusion

Due to the ability to restore from past backups, we recommend using a locally attached External HDD instead of a NAS. This way, you get almost all the benefits (such as full automation) without the drawbacks.