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Can users add their own custom modes?
The software environment of the PC-3000 complex for Windows including Data Extractor PCI as its integral part allows creation and use of programs in Visual Basic, which can address all COM objects within the software complex as well as custom objects. The feature extends considerably the range of opportunities provided by the complex to qualified users.
Examples of application:
A drive with lots of defective sectors (UNC, AMNF, IDNF errors), which however does not produce knocking sounds while working.
Identification of location and volume of required data (with customer participation) must be the first action, which should precede complete disk copying.
If a customer needs all drive data irrespectively of the degree of physical damage or cost then there would be sense in creating a full copy on another drive and only then proceed to the analysis of damage to the logical structure, if necessary.
If a specific partition has to be recovered, its position should be checked precisely using the Explorer mode (map of MBR or a respective partition). Even when MBR is corrupted and the location of necessary partition cannot be identified in it, you should try searching for boot records to obtain necessary information from them. However, one should avoid searching through the whole disk, one record would be enough to find information about partition size, then proceed searching for the next one; such procedure would save a lot of time (especially on a remarkably corrupted disks).
If a disk is really seriously damaged or if you suspect that it may stop working soon then you should define the most important data before making a full copy and use the Explorer mode to save that data first if the damage allows that. Then proceed to copying all the disk contents.
If the data volume is relatively small the Explorer mode will be preferable.
If you have decided to copy a clearly defined area, there would be more sense in doing so in two or more passes:
Quick pass without stops to retry reading of sectors copied with errors. The number of reading attempts should be minimal. You can use the "Skip sectors causing errors" option and specify jump size for reading of sectors that produce errors. That initial pass is intended for copying of the main easily accessible data portion from a drive, which may stop working. A variety of commands used for reading is available.
Refining pass with a higher number of reading retries on defective sectors (depending upon drive condition), the "Skip sectors causing errors" option is disabled, jump size in case of an error while reading is 1 sector. Please note that a serious increase of reading retries would be useful only for drives demonstrating unstable reading. It does not make sense when a drive reads invalid information from defective sectors. Sometimes it may be helpful to set the "Read, ignore CRC" option for time saving.
All subsequent passes might be useful for specific areas only (tables, files, folders...).
A drive that hangs at an attempt to read defective sectors.
Recommendations for work with such drives would be the same as in the previous situation.
One exception - you can use a script to define program actions while reading defective sectors. Script contents would depend on drive behaviour. As a rule, a software reset or a combination of software and hardware reset should be sufficient. Sometimes it may be necessary to switch off the power supply.
A drive producing knocking sounds at an attempt to read defective sectors (seriously damaged surfaces, scratches or reading head malfunction).
Recommendations are identical to the first case, but the script of program behaviour at readiness loss must include the "Power off the drive" action. Set the size of jumps to be used while reading defective sectors equal (or slightly larger) than the number of sectors per physical track of the drive. Possibly the value will have to be adjusted during the process of data recovery in the middle and in the end of disk surface. The option will allow reading all accessible data from the remaining undamaged surfaces before MHA replacement. If the required data can be found within that area, MHA replacement may even become unnecessary.
Imitation of readiness loss.
Sometimes a lot of time is wasted trying to read defective sectors. That may be unacceptable when such sectors are rather numerous. Besides, the damaged areas do not invariably match the necessary data.
Of course, you can set a jump size for reading sectors containing errors and "jump over" the corrupted areas, but the time necessary for a single attempt of reading a defective sector may be too long anyway. In that case you can simulate loss of readiness by the drive by setting the latency period so that normal sectors would be read without hassles but even a smallest slow-down would trigger loss of readiness and consequently a jump. The specified latency period can be set to 0.5-1 second. You should remove all unnecessary actions from the script to be used at readiness loss (especially commands to switch power off). A software reset would be generally sufficient.
As soon as the data accessible without problems are copied, disable the "Skip sectors with loss of readiness" option and return the latency interval to the initial value.
Then proceed as the situation may demand: use the Explorer mode to copy data or perform the second pass for recovery of more information from damaged areas.
A drive with MHA problems
The problem manifests itself as follows: long areas of successfully copied data (marked light green on the map) are regularly alternated with areas, which either cannot be read at all or can be read with errors.
For drives with such problems you will have to make a complete copy of a disk or a required partition. If you can create a heads map then perform the procedure and first copy the data from functional heads and only then proceed with reading information from the remaining ones (possibly, after MHA replacement).
If you cannot create a heads map (the algorithm does not work out), use jumps at HDD readiness loss (maybe you will not even have to simulate it, but the latency period can be reduced) or jumps at sector copying with errors to bypass zones corresponding to faulty heads. Select jump size so that it takes 1-2 jumps to cross a zone matching a faulty head.
As soon as a copy is created, proceed with the restoration of logical structure, but those operations should be performed on a virtual copy instead of the actual damaged drive.
An IBM HDD with numerous soft BAD sectors.
Soft BAD sectors are errors, which are not related to the defects of magnetic surfaces or heads. They appear as a result of software failure in drive operation, which may occur while recording. Consequently, CRC code written to parity field does not match the value calculated using the sector data producing thus a UNC error. Such malfunction is very frequent in IBM/HGST drives.
The situation has three typical peculiar indicators:
The time used for an attempt to read a defective sector is very large (about 8 seconds).
Those sectors usually occupy sequential areas consisting of several dozens in a row.
Usually there is no sense in multiple attempts of reading the defective sectors. They are always read with errors and their content is so damaged that statistical processing yields little results (still, an increased number of retries does make sense for areas of FAT tables and directories).
In such cases it is usually expedient to employ the above-described method of simulated readiness loss for creation of a full data copy. Then switch to the Explorer mode and use the "Read, ignore CRC" command, it will save you a lot of time.
A drive with damaged logical structure
Such situations may appear, when a drive is physically functional, but its data cannot be accessed because of corrupted logical data structure or when a drive was damaged and data image creation has been successful but the share of successfully copied sectors in the resulting image is less than 100%.
When you are creating a copy of a drive with physical malfunctions causing damage to logical structures, the use of the additional Explorer, GREP search, View and edit sector modes to speed up access to drive data would be really expedient.
E.g., if physical problems resulted in damage to MBR, the most efficient method would be its reconstruction (by filling in the partition information) to gain access to data quickly. The same holds true for boot sectors of partitions. When you are dealing with NTFS partitions and the situation is complicated by problems both with 4 initial records in MFT table and with MFT Mirror it may be helpful to use the partition map to assemble one full copy of 4 initial records from two original copies.
If you can scan the MFT table, do that. It is the fastest method to build a virtual file system (unless you can see it in Explorer at once) and gain access to necessary data. An MFT table may occupy up to 10% of partition size, so you will not have to copy everything (the task may be difficult or even impossible) to extract, e.g., 1 Gb of data.
As a rule, it is recommended to perform serious logical structure analysis after creation of data copy on a functional drive connected to a standard port (UDMA100 or faster).
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