Data Recovery Guide

• Data recovery plan overview
• Mechanical vs. software problems
• Common data recovery scenarios
• Types of data recovery
• Hardware and disk space
• Performing a data recovery
• Using boot CDs
• Various aspects

Hardware and disk space

General hardware considerations.

The data recovery is sensitive to the hardware quality because the process uses all the components of the system intensively. You need a perfectly functioning system; otherwise the system might crash during the run.

Following are the typical items to check before starting

• Stop all the overclocking (if somebody still does it these days). Revert to certified parameters at least for the duration of the recovery.
• Check if the system memory is operating properly. Use Windows Memory Diagnostic to perform the test. If the test fails, fix or replace the appropriate components before starting the recovery, or move the hard drive to a different computer.
• Make sure the power supply unit provides enough power for all the additional hard drives you may have installed. Also, if the PSU is more than three years old, consider replacing it. You may want to review the article on power supply failure identification and troubleshooting for more details.
• Avoid overheating. Ensure appropriate ambient air temperature and efficient ventilation. Check that all the fans are actually rotating and the airflow is not obstructed by either cabling or the accumulated dust.

Disk space requirements.

For a read-only recovery, you need enough free space on the known-good storage volume to hold all the recovered files. Also, if the files on a damaged volume were compressed using built-in NTFS compression, you should either ensure that the extracted data is also stored compressed, or factor the compression into your estimation of the disk space requirements for the particular recovery.

If you are planning to fix the volume in-place, consider making an image of it, just for the case. The image requires an amount of free space equal to the size of the volume.

When dealing with the RAID, the worst case requirement is to have an available space twice the size of the original array. This covers possible need to unroll the array into the continuous disk image before starting read-only recovery. In this case, you need to hold both the unrolled image (same size as the array) and the recovered files at the same time.

When choosing the storage to hold the recovered data, keep transfer speeds in mind. A directly-connected hard disk (e.g. SATA) is the best choice, and an USB hard drive is the second best option. Offloading recovered data over the Gigabit Ethernet network is still acceptable, but 100 MBit is too slow for most of the usual data recovery scenarios. Do not use WiFi networks to transfer recovered data because they are too slow and lack reliability under continuous load.

During the read-only recovery run it is possible to extract more data than you originally had on the drive. This is because multiple versions of the same file may be restored, and also because of the imperfectness of the recovery process. It is thus reasonable to plan for slightly larger storage than anticipated.

Continue to Performing a data recovery.