2026-04-24

SQL & SQL Database File Recovery

DATARECOVERYUNION.COM07 mins

Microsoft® SQL server is a business enterprise software package that manages data through a client/server relational database. There are four fundamental aspects to a SQL (Structured Query Language) server.

1. Database File
2. Relational Database Concept
3. Client/Server System
4. Database Management System (DBMS)

The Database File refers to the physical file that contains the data the SQL server manages. This file is more than just a container for data. SQL files, or .MDF files, are highly organized and complex. The file is designed like this so that SQL server can handle multiple data transactions at once.

The Relational Database Concept is the method employed to organize the data; this is separate from the internal organization of the file itself. Relational Database Concept systems use mathematical set theory to organize the data in the most effective way. Data organization is critical to maintaining the speed of the database server.

The Client/Server System refers to the part of SQL server that communicates with the operating system. This part of the system needs to manage the server’s resources, connections and managing multiple databases at the same time.

The Database Management System interacts and works will all the above items. Not only does this manage the internal structure of the .MDF file, DBMS also controls the Relational Database side of things and organizes the data. The DBMS of SQL server is the heart of the system.

Data loss situations-What can happen?
Data loss situations can occur at a number of different levels. The first level of data loss starts with the storage device. This can be a single hard disk or a SAN or RAID storage array. The second level of data loss can start at a file system level. The file system is a unique method of storing and organizing system and user files. The operating system controls the file system. If the information about where data files are on the volume are damaged or lost, then adjustments or repairs need to be completed at a file system level. Once the file system is repaired then the file’s data stream can be accessed correctly. Most operating systems have a utility that will automatically fix the file system. These utilities work to make the volume accessible. However, this can permanently damage the data stream of the file. The third level of data loss can occur within the file itself. As previously mentioned, .MDF files are quite complex. The internal structure can be corrupted to the point where the DBMS will not make the database available.

The solution to data disasters
The process of a SQL recovery begins with finding the database file requested. If the database file is inaccessible due to problems with the storage device, then should work to get that data extracted. If the file is missing, deleted or truncated due to problems with the file system, then should work to adjust or repair the file system to correctly point to the data stream of the file. And finally if the file system has no pointers at all to the file, then should search the entire drive looking for SQL data.

The next stage is to work on the database file itself. This is where the SQL toolset comes. These tools analyze the complex internal structures of the .MDF file and provide reports as to what tables are recoverable. The reports also list the number of data rows that will come back.

Once the evaluation is complete and authorization is given to recover the data, the SQL toolset will copy the data into another SQL server database. After this phase is complete, we can backup or archive the recovered data.

Remote Data Recovery is the fastest solution for SQL recoveries. The Remote Data Recovery process will copy the recovered data into a SQL server that is setup on you or your client’s site. They only need SQL server running. For best results I recommend that the storage device we are working on be connected to a SQL server, because all of the data transactions will be occurring on a single machine.

Read More

CD Optical Storage Glossary of Computer Terms (Letter M)

DATARECOVERYUNION.COM01 mins

Magenta
The color obtained by mixing equal intensities of red and blue light. It is also the correct name for the subtractive primary color usually called red.

Magneto-optical
See CD-WREM.

Mastering
A real time process in which videotaped materials are used to create a master optical disk that can be replicated into final videodiscs or CD-ROM disks for operation with desktop computers. Usually performed by an outside specialty shop.

Media
Specific means of artistic communication including forms such as film, art, voice, music, sounds, text, programming etc.

MIDI
Musical Instrument Digital Interface. It is a series of digital bus standards for interfacing of digital musical instruments with computers.

Morph
The special effect merging object attributes from multiple images into composite views

Read More

Western Digital HDDs’ Noise related to PCB

DATARECOVERYUNION.COM06 mins

Causes & Solutions of Two Main types of Noise Which is occured in Western Digital HDDs (Especially Related To L-shape PCBs)

Clicking Noise and Continuous Noise

1- The Clicking Noise
when u power on the hard drive u will hear a noise like (click,click….click,click…click,click)
this noise may be related to the head stack or PCB, the first thing you have to do is to check the PCB By The following steps:

  1. first you have to clean the Whole PCB With a Solvent & Toothbruch then wipe it with a piece of smooth handkerchief to remove the dust & dirt from it.
    Caution: Cleaning of the PCB must be done carefully to avoid removal of any small electronic components.
  2. Check the Resistor (R120) , [ the right value of this Resistor is (0.12 Ohm) ] ,u may adjust ur multimeter to Resistor Measuring Mode to Determine its Value ,if it’s Damaged u have to replace it. but before that, u have to check Transistor Q3 , it’s a 6 pins transistor , for measuring this transistor u may adjust ur multimeter to Diode Mode,[ the right Value will be: (first two pins = 0.000 , second two pins =0.000 , Third two pins = nearly over 600)]
    if Q3 is Damaged it will burn ur R120 after u replace it , so be sure that Q3 is ok before replacing R120 & u may also Check Transistor Q6 by the previous method to be completely sure it’s safe to replace R120.
    Note: ( to be sure of The right values of these electronic components u may compare the values u have measured with the values of a working PCB’s Components)
  3. Check The Coils (such as L2 & L7) – adjust ur multimeter to diode mode then the right value must be ( 0.000 ) for any coil as u all know.
  4. inspect the whole PCB for any removed component ( such as small capacitors or Resistors ) … the removal of these small components may occured while forced cleaning of the PCB …. so becareful while cleaning it.
  5. in rare cases the firmware microchip may be damaged.

western-digital-pcb

Resolution image which shows all the Western Digital PCB Electronic Components I have mentioned above.

2- The Continuous Noise

sometimes there is a continuous noise come from WD HDDs mainly with L-shape PCBs
with motor ICs ( Smooth 1.3) , (L6278 1.7) & (L6278 1.2).
the noise is like : Trrrrrrrrrrrrrr or Trrrr….Trrrr…Trrrrr

so all we have to do for fixing this problem is:

  1. 1- clean the connection points which connect the head stack pins with the PCB using a pencil Rubber …carefully.
  2. 2- clean the motor IC pins thoroughly using a solvent & Toothbrush then wipe it with a piece of smooth handkerchief to remove the dust & dirt from it.
    -Note- the two steps mentioned above solve the problem in few cases.
  3. 3- if the two steps mentioned above didn’t fix the problem , you have to replace the motor IC cause it’s damaged.

Note: in case of Motor ICs (L6278 1.7) & (L6278 1.2) first try to desolder them then resolder them again before u decide to replace them with a new ones … this sometimes work , but if it didn’t work … replace them directly.

In case of Motor IC (Smooth 1.3) you must replace it directly. Image below Shows you where to clean.

WD-PCB

Useful Resources:

Read More

RAID Array & Server Glossary of Computer Terms (Letter S)

DATARECOVERYUNION.COM111 mins

SCSI
Small computer system interface (pronounced scuzzy). The fast, intelligent input/output parallel bus used by high-performance peripherals.

Software-based array
An array in which all management functions including parity calculation (XOR) are performed by the host server CPU. These products are low priced but have high CPU utilization and limited fault-tolerant features. High-performance, low-cost array adapters are quickly replacing these inferior software-based arrays.

System disk
The disk (or array) on which a system’s operating system is stored and from which it is initially loaded into system memory.

SAF-TE
SCSI Accessed Fault-Tolerant Enclosure, an “open” specification designed to provide a comprehensive standardized method to monitor and report status information on the condition of disk drives, power supplies, and cooling systems used in high availability LAN servers and storage subsystems. The specification is independent of hardware I/O cabling, operating systems, server platforms, and RAID implementation because the enclosure itself is treated as simply another device on the SCSI bus. Many other leading server, storage, and RAID controller manufacturers worldwide have endorsed the SAF-TE specification. Products compliant with the SAF-TE specification will reduce the cost of managing storage enclosures, making it easier for a LAN administrator to obtain base-level fault-tolerant alert notification and status information. All Mylex RAID controllers feature SAF-TE.

Sector
The unit in which data is physically stored and protected against errors on a fixed-block architecture disk.

Segment Size
See Cache Line Size

Sequential I/O
A type of read and write operation where entire blocks of data are accessed one after another in sequence, as opposed to randomly.

SES
SCSI Enclosure Services, a standard for SCSI access to services within an enclosure containing one or more SCSI devices. For disk drives, power supplies, cooling elements, and temperature sensors, the actions performed are the same as for SAF-TE monitoring. If a UPS is connected to any SES-monitored enclosures, and an AC failure or two minute warning is reported, conservative cache is enabled and all system drives are switched to write-through cache. Primarily used in fibre enclosures.

Session
The period of time between any two consecutive system shutdowns; system shutdown may be either a power off/on, or a hardware reset.

SMART
Self-Monitoring Analysis and Reporting Technology, the industry standard reliability prediction indicator for both the ATA/IDE (advanced technology attachment/integrated drive electronics) and SCSI hard disk drives. Hard disk drives with SMART offer early warning of some hard disk failures so critical data can be protected.

Spanning
A process that provides the ability to configure multiple drive packs or parts of multiple drive packs. In effect, spanning allows the volume used for data processing to be larger than a single drive. Spanning increases I/O speeds, however, the probability of drive failure increases as more drives are added to a drive pack. Spanned drive packs use striping for data processing. See also Striping and Drive Groups, Drive Packs.

Standard Disk Drive
This term refers to a hard disk drive with SCSI, IDE, or other interface, attached to the host system through a standard disk controller.

Standby Replacement of Disks
See also Hot Spare. One of the most important features the RAID controller provides to achieve automatic, non-stop service with a high degree of fault-tolerance. The controller automatically carries out the rebuild operation when a SCSI disk drive fails and both of the following conditions are true:

  • A “standby” SCSI disk drive of identical size is found attached to the same controller;
  • All of the system drives that are dependent on the failed disk are redundant system drives, e.g., RAID 1, RAID 3, RAID 5, and RAID 0+1.

Note: The standby rebuild will only happen on the same DAC960 controller, never across DAC960 controllers.

During the automatic rebuild process, system activity continues as normal. System performance may degrade slightly during the rebuild process.

To use the standby rebuild feature, you should always maintain a standby SCSI disk in your system. When a disk fails, the standby disk will automatically replace the failed drive and the data will be rebuilt. The system administrator can disconnect and remove the bad disk and replace it with a new disk. The administrator can then make this new disk a standby.

The standby replacement table has a limit of 8 automatic replacements in any session (from power-on/reset to the next power-off/reset). When the limit of 8 is reached and a disk failure occurs, the standby replacement will occur but will not be recorded in the replacement table.

To clear the “standby replacement” table, reboot the system from a DOS bootable floppy, run the configuration utility and select the option ‘view/update configuration’ from the main menu. A red box labeled ‘Drive Remap List’ will be displayed. Selecting the box will allow you to continue. You should save the configuration without making any changes, and exit the configuration utility. This will clear the replacement table. You may now proceed to boot your system and continue normal operations.

In normal use, the replacement table limit of 8 should not cause any problems. Assuming that a disk fails about once a year (drives we support generally come with a 5-year warranty), the system would run continuously for a minimum of 8 years before the table would need to be cleared.

Storage Device
A collective term for disks, tape transports, and other mechanisms capable of non-volatile data storage.

Stripe Order
The order in which SCSI disk drives appear within a drive group. This order must be maintained, and is critical to the controller’s ability to “rebuild” failed drives.

Stripe Size
The size, in kilobytes (1024 bytes) of a single I/O operation. A stripe of data (data residing in actual physical disk sectors, which are logically ordered first to last) is divided over all disks in the drive group.

Stripe Width
The number of striped SCSI drives within a drive group.

Striping
The storing of a sequential block of incoming data across multiple SCSI drives in a group. For example, if there are 3 SCSI drives in a group, the data will be separated into blocks. Block 1 of the data will be stored on SCSI drive 1, block 2 on SCSI drive 2, block 3 on SCSI drive 3, block 4 on SCSI drive 1, block 5 on SCSI drive 2, and so on. This storage method increases the disk system throughput by ensuring a balanced load among all drives.

Sub-System Storage
A collection of disks providing data storage space to a system user.

Read More