How to Find a Better Donor Drive

4 September 2013

More and more data recovery jobs require donor drives these days, because mechanical hard drive failures are on the rise. Modern hard drives are constantly increasing in density, and manufacturers are using more inexpensive components, which leads to higher failure rates. And with increased density and the greater precision of mechanical parts, it’s becoming harder to find compatible donors for part replacement.

Technicians looking for compatible donor drives typically rely on information located on the drive’s label such as model name and manufacturing date. However, that information is often not enough to identify compatible mechanical parts or logic boards. In fact, the info can actually be misleading.

For example, when searching for a compatible Western Digital donor drive, many technicians try to match specific characters of the DCM code found on the label. Finding a donor with a close DCM code can be helpful, but often that’s not enough. Sometimes donors with more distant DCM codes turn out to have a better compatibility.

So, what else can you take into consideration when searching for a better donor drive? Look at vendor-specific parameters related to compatibility. Such parameters not only identify the types of parts the drive is assembled from, but they also contain adaptive data that reflects the performance characteristics of parts that are unique for each drive.

Again, taking Western Digital drives as an example, several vendor-specific parameters located in the ROM and RAM of the drive help in finding a donor with better compatibility:

  • Head map
  • Microjog adaptives
  • Drive information table
  • Firmware release

Unfortunately, none of these parameters are located on a drive’s label. However, you can retrieve them using some data recovery tools.

The head map points to which physical heads on the head assembly are used by the drive. For instance, two drives may have the same number of heads, but those heads may be located at different positions on the head assembly and access different disk platters. You can find drives manufactured on the same day that have the exact same information on the label, yet they have different head maps. Obviously, such donors are not compatible. Always check the head map before opening the donor drive. There is nothing more frustrating than acquiring an expensive donor drive for an urgent case and finding out that it has a different set of heads.

Microjogs are head-specific adaptive parameters that are calculated and tweaked during hard drive manufacturing tests. These parameters are used to optimize hard drive performance and are programmed into the hard drive’s ROM. When heads from another hard drive are installed into a patient drive, these parameters no longer correspond to the actual head characteristics. If the difference in microjogs is significant, the heads cannot operate at all, making these heads incompatible.

The drive information table is a firmware table that contains information about the types of components the drive is assembled from. Hard drive vendors may use different components while assembling the exact same model of the drive. These components may be different types or they may come from different suppliers. As a result, characteristics of these components, such as preamplifier or motor controller chips, can change from day to day. The drive information table helps in finding a donor with a better compatibility, since you can search for a drive with similar mechanical and electronic components.

Firmware release parameters, such as firmware ID and firmware overlay, identify the drive with a compatible firmware and can be used to locate a donor drive needed for firmware repair purposes or hot swap recovery procedures. This firmware release information is not located on the drive’s label or within the drive identification data.

Knowing these vendor-specific parameters definitely increases your chances of finding a compatible donor drive. Note that these parameters do not provide a 100% guarantee that the donor parts will be fully compatible. However, for all newer drives, it is becoming nearly impossible to find a perfect donor without taking into account vendor-specific information related to the drive’s compatibility.

Here are some examples of vendor-specific parameters that help in identifying the right donor drive:

Microjogs: 3592,3348,3570,3330,3570,3280,3530,3326
Microjogs Avg: 3443
Head Map: 0,2,3,5,6,7,8,9
Firmware ID: 80.00A80
Firmware Ovl: 00200049
MCU Type: 0000-7412
Channel Type: 0039-0023
Preamp Type: 0000-0004
Power IC Type: 0000-2100

Seagate ST9500420AS
Firmware ID: D005SDM1
Preamp Type: 5B 02
MCU Type: TETONST_4(63A2)(3-0E-4-2)

To meet the increased demands of the data recovery industry, the latest release of DeepSpar Disk Imager now makes it possible to pull up vendor-specific parameters related to the compatibility of parts for most drives that are sensitive to these parameters.

In addition, DeepSpar Data Recovery Systems has launched an initiative to create a shared database of donor drives for the data recovery industry: Now, every user of DeepSpar Disk Imager 4 can easily look for a donor drive with better compatibility by searching through the inventory of many data recovery companies. An Internet browser with a DeepSpar plugin automatically pulls up the selected compatibility parameters of a patient drive from DeepSpar Disk Imager over the LAN and queries the shared database for available donors that have better compatibility to a patient drive. Also, companies that have extra stock of donor drives can list their drives on this shared database simply by connecting the drive to DeepSpar Disk Imager and pushing a button to populate all of its information from the model to vendor-specific parameters.

As donor drives become more important than ever, DeepSpar is committed to making it easier for you to find the right ones.