Diagnostic Commands in data recovery

Diagnostic Commands is very important in Data Recovery steps.

When working in terminal mode, users need to use diagnostic commands to communicate with HDD. And some users don’t know how to use those commands. Therefore, here is a topic on diagnostic commands. This article will introduce some frequently used commands.

In terminal mode, the HDD will output diagnostic message to the log after power reset. After pressing keyboard [Ctrl] + [Z], you will get a prompt of “T>” (or “F>” for malfunction HDD), then you can input diagnostic commands.

HDD works in different Levels (commands level). In the aim of easy management, engineers of Seagate assort diagnostic commands into levels and HDD has different Levels. Command “/x” will switch HDD to work in different Levels.

Meanwhile HDD can run in different Ages (program level). Command “;” will tell you current Age. The output format is like the following:

From the output, we know HDD works in Level T and Age 50, and it has one head (Heads Number=MxHd+1).

According to current Level and Age, users can basically judge whether the drive works in good condition. Functional HDD works in Level T and Age 50. Then users need to examine firmware condition. First, users can issue command “%” to know the location of service area. The output will tell you serial number (5LR01EWA) and cylinder location of service area (15F6B-16908).

Besides, command “y” will show you firmware location in service area. But the command is not available for all drive families. And it’s only valid after cert is loaded, namely users need to execute command [Ctrl] + [R] first.

Firmware location tells you in which cylinder the module locates. For example, first copy of APP code locates in cylinder 15F81. Here, UsrDfect is P-List; Alt Pool is G-List; IntfCode is ATA; Intf Sys is INFO. (PS: SMART module locates in the same cylinder with G-List, Alt Pool.)

If firmware location is known, users can make drive seek there to read firmware contents. In that way, users can judge whether there are bad sectors located in the cylinder. Seeking and reading commands are executed in Level 2. Seeking command is “sx,y,22″, where x represents for cylinder and y for head. Reading command is “r,x,y”, where x stands for initial sector in the cylinder and y for length in sectors. (The following example is to seek to Alt Pool cylinder and read 1 sector from sector 0). If terminal hangs up after read command, it means there are bad sectors in the cylinder. Attention: The primary head is generally head 0, it’s advised to seek to the cylinder of head 0, namely “sx,0,22″.

How to check the read firmware content? You can use command “Bx,y”, where x means read buffer and y is compared buffer. However, prior to that, you should know the address of read buffer, which can be accomplished by command “?”. (RD: 04B4 is read buffer.)