The SCSI Disk Expert Tool provides low-level disk functions to test, format or examine a disk in depth. You can also repair a disk by sparing bad blocks. The SCSI Disk Expert Tool is fully interactive, with its own set of menus.
CAUTION: The SCSI Disk Expert Tool contains commands which can destroy data or impair the functioning of the disk if used improperly (for example, Format Unit, Reassign Block, and Write).
To use the SCSI Disk Expert Tool safely, you should be trained and knowledgeable about SCSI disks.
The SCSI Disk Expert Tool allows low-level access to SCSI disk devices by issuing SCSI commands.
Although this tool uses the term "SCSI", the real name for the protocol is SCSI-2. SCSI-2 is a popular standard protocol for a class of devices such as disks and tapes. SCSI-2 includes:
The SCSI Disk Expert Tool requires that you install a license at the main STM window.
If you experience problems, consult the Troubleshooting Tool-Related Problems help topic.
To run the SCSI Disk Expert Tool on a device:
If you want to test several disks simultaneously, select a disk, start an instance of the expert tool, select another disk, start another instance of the expert tool, and so forth.
The following procedure is one possible method for troubleshooting disks. The idea is to perform quick tests first to find easy problems then to perform more time-consuming tests to find less obvious problems.
To troubleshoot a suspect disk:
Alternately, you can do stress testing from within the expert tool, for example:
If you run into problems, see the Troubleshooting Tool-Related Problems help topic.
Consult the Failure Log (for failures) and the Test Activity Log, accessible from the STM main window.
Make sure the device is connected, powered on, and on-line. You could try running the verifier on the device to see why the device is not responding.
If the selected disk is a system (root) disk, some of the SCSI Disk Expert Tool functions can cause the computer system to become slow or non-responsive.
You can stop the executing function by pressing the Interrupt Button in the window of the expert tool. To stop the expert tool entirely and return to the xstm Main Window, press the Abort Button.
To reduce the chance of this problem occurring, specify a smaller scope for the function. For example, with the Verify command, select a block or range of blocks rather than the entire disk.
The SCSI Disk Expert Tool may be waiting for you to respond to a query message it is displaying. Look underneath the windows on your workstation for a query message. Also, de-iconize any windows related to stm or the expert tool.
The SCSI Disk Expert Tool requires a license to operate. Install the license at the main STM window and try to run the tool again.
The SCSI Disk Expert Tool offers the following commands and buttons:
Use the Exit command to leave the SCSI Disk Expert Tool and return to the main STM window.
The View Log command displays information from the internal log of the disk (counters). This log records the occurrence of events such as data errors and hardware faults. Logged data may include:
The Clear Log command clears the drive's maintenance log, resetting the error counters within the disk mechanism.
CAUTION: Clearing the logs will permanently delete service-related information from the disk.
The Capacity command displays the following information for the selected disk drive:
Running this command is a quick way to check if the disk is responding.
The Growing command displays the Growing Defect List for the drive. The Growing Defect List includes all physical surface defects identified after the drive leaves the manufacturer.
Full path: Info | Defect List | Growing
The Primary command displays the Primary Defect List for the drive. The Primary Defect List contains the physical surface defects detected on the media by the original manufacturer.
Full path: Info | Defect List | Primary
The Both command displays both the drive's Primary Defect List and the Growing Defect list. The Primary Defect List contains the physical surface defects detected on the media by the original manufacturer. The Growing Defect Iist includes all physical surface defects identified after the drive leaves the manufacturer.
Full path: Info | Defect List | Both
The Inquiry command displays the following information for the selected disk drive:
Running this command is a quick way to check if the disk is responding.
The Selftest command starts the internal power-on selftest for the selected device. Tests are device-dependent and are described in the support documentation for each drive.
After selecting the test, you are queried for the number of loops for the test to execute (default is 1).
The Alternate command causes the drive to perform seeks between two specified addresses. The command is useful for testing the servo circuitry (head positioning mechanism).
After selecting the test, you are queried for the addresses of the two blocks between which the seek is performed. You are also queried for the number of loops for the test to execute (default is 1).
Full path: Tests | Seek Test | Alternate
The Butterfly command causes the drive to perform a series of seeks over the entire disk surface. The test moves the drive heads between the innermost track and the outmost track, then works its way towards the center of the tracks. The command is useful for testing the servo circuitry (head positioning mechanism).
NOTE: The Butterfly command can take a long time to execute.
Full path: Tests | Seek Test | Butterfly
The Random command causes the drive to perform a seek to a random address. The command is useful for testing the servo circuitry (head positioning mechanism).
After selecting the test, you are queried for the number of loops for the test to execute (default is 1).
Full path: Tests | Seek Test | Random
The Verify command verifies the data on a selected or random area on the surface of the drive's media.
After you start the test, you are queried for:
The Clear Drive Logs option resets the counters on the device before execution of the Verify command. With this option selected, you can read the counters with the View Log command immediately after executing the Verify command to learn the various type of errors that were encountered during the Verify command.
If you choose "Random Area" option, the tool randomly generates a start address and an end address for verification. All blocks in this range are tested sequentially. This option is useful when you want to exercise the drive but are not concerned about a specific area.
If you choose "Selected Area" option, you specify a "Start Block Address" and an "End Block Address" for verification. All blocks in this range are tested sequentially.
For each loop (iteration), the Verify command sequentially verifies the range of blocks randomly selected or that you have selected.
The Format Unit command prepares a new disk for access by initializing all data surfaces and organizing the sectors into logical blocks. Surfaces with defective areas will be relocated to ensure data reliability.
CAUTION: The Format Unit command will destroy all user data on the disk drive! If you want to preserve data on the disk, press "Cancel" to cancel the command.
The Format Unit command can take a long time to execute. The time required for the Format Unit command depends on the capacity of the disk drive (about 1 second per Mbyte). For example, formatting a 1-Gbyte (1000-Mbyte) drive takes about 1000 seconds, or 17 minutes.
CAUTION: Before you start the Format Unit command, make sure that this is what you want to do! Once the command has begun, it cannot be stopped; it does not respond to Abort Button. or Interrupt Button.
You can optionally choose to retain both Primary and Growing Defect Lists during the formatting process. The locations of these defects will be remapped to other more reliable locations.
The Primary Defect List consists of the physical surface defects detected on the disk drive by the original manufacturer. The Growing Defect List consists of all physical surface defects identified after the drive has left the manufacturer.
A second option is to retain only the Primary Defect List. The Primary Defect List consists of the physical surface defects detected on the disk drive by the original manufacturer. The locations of these defects will be remapped to other more reliable locations.
If you choose this option, the Growing Defect List is re-initialized and re-built as data consistency problems are experienced during normal operation. When defects are identified, the data may be automatically relocated.
The Identify Blocks command identifies the usage of specified blocks on the device.
If you suspect particular blocks on the disk are bad, you can execute this command to find how the blocks are used by the file system. If you find, for example, the blocks are used to store part of a file, you can recover the data by restoring that file.
The Read command reads any block of data on the selected device into a buffer for examination and for subsequent write operations (the Write command).
By default, the data is displayed in both hexadecimal and its ASCII equivalent. You can optionally choose to turn off the display of data.
The command only buffers one block of data at a time, so multiple read operations overwrite the previous content of the buffer.
The Read Long command reads any long block on the selected device into a buffer for examination. A "long" block contains the standard data field and the additional header field on each block. This header field also contains the ECC information for the given block of data.
By default, the data is displayed in both hexadecimal and its ASCII equivalent. You can optionally choose to turn off the display of data.
The command only buffers one block of data at a time, so multiple read operations overwrite the previous content of the buffer.
The Reassign Block command moves the data from one physical address to a physical address in the spare area. The logical address is then remapped to the new physical location. The physical address from which the data is copied is added to the Growing Defect List. The purpose of this command is to move data from an area with defects to an area which is defect-free.
CAUTION: Do not use the Reassign Block command unless you know that the block is defective, for example by running the Verify command on the suspected area and finding that it consistently generates errors.
Unnecessary use of the Reassign Block command uses up spare tracks, reduces performances, and may cause data loss.
After you select the command, you are prompted for logical block address to be reassigned.
You are also prompted for the number of times a logical block reassignment should be attempted if the original and/or subsequent spare blocks are found to be defective.
The Write command writes data to the disk drive and can be used to verify the operation of the device's write circuitry. This command has three variations:
After you select the Write command, you are queried whether to perform a Write, a Read-then-Write, or a Read-Long-then-Write-Long. You are also queried for the destination block(s) for the operation.
CAUTION: The Write operation will write data to any block you specify on the disk. Data that currently exists in the block will be destroyed.
Before you execute the Read-then-Write operation or the Read-Long-then-Write-Long operation, you should make sure the disk is idle (for example, by unmounting the file system on it). With the disk idle, these operations are non-destructive because they write data back to the location from which it was originally read.
CAUTION: There is a possibility of corruption during a Read-then-Write if a write from some other source is performed on the drive during the operation.
For example, if the tool reads a block of data and then a user or the OS writes new data at that block, data corruption will occur when the tool writes the old data back to the block. Data corruption can also occur if another CPU is sharing the drive and it performs a write during a Read-then-Write operation.
The Interpreted command causes internal status data or logs to be displayed or printed in an interpreted (ASCII) format.
Full path: Options | Display Format | Interpreted
The Hex command causes internal status data or logs to be displayed or printed in a hexadecimal format.
Full path: Options | Display Format | Hex
The Both command causes internal status data or logs to be displayed or printed in both an interpreted format and a hexadecimal format.
Full path: Options | Display Format | Both
The General Help command displays online help for the SCSI Disk Expert Tool (the help system you are currently viewing).
For information on using the help system, select the "Using Help..." command in the Help menu in this Help window.
For online help on STM as a whole, use the Help menu in the STM main window.
The Version command displays version and copyright information for the SCSI Disk Expert Tool.
The Abort button allows you to abort the SCSI Disk Expert Tool, halting its execution and returning to the STM main window.
The tool will be requested to abort and the state of the tool execution in the system map will be set to ABORT_PENDING. When the tool actually exits, its state will be set to ABORTED.
The Interrupt button allows you to interrupt the tool. When the tool receives the interrupt, it will prompt you if you want to continue with the operation. If the reply is "Continue", the tool resumes what it was doing at the time of the interrupt. If the reply is "Abort", it terminates the operation and returns to the window for the SCSI Disk Expert Tool.