What is RAID?

RAID is the acronym for either ‘redundant array of inexpensive disks’ or ‘redundant array of independent disks’.  When first conceived at UC Berkley the former was the actual term that was coined but the latter is more commonly used today intentionally to disassociate the technology from the word inexpensive and the perception that RAID somehow implies a low cost solution.

Why Use RAID? 

RAID is a storage technology that provides increased data reliability through data redundancy.  This is achieved primarily by duplicating data across several storage drives in a configuration referred to as an array of disks.

How Many Different Types of RAID are There? 

There are several different types of RAID array configurations each type being denoted by a single digit numeral, 0 through 6 (and various combinations thereof).  These types are commonly referred to as RAID ‘levels’.

What Distinguishes one RAID Level From Another?

The makeup of the different RAID levels is varying combinations of redundancy, spanning, mirroring and striping.

What is Redundancy?

Redundancy is the duplication of data onto more than one physical drive to increase fault tolerance.  If one physical drive in a redundant array fails no data is lost and there is an opportunity to replace the failed device.  As long an one drive is functional, data is secure.  However, in the case of a failure, the failed device must be replaced and the array rebuilt onto the new device.  In very large data structures this can sometimes take a great deal of time.  If there were to be a failure during the process of rebuilding the array all data would be lost.

What is Spanning?

Spanning is the configuration of two or more physical drives into one ‘logical’ drive.  The logical drive is treated exactly the same as a physical drive and will appear as just one device.  Spanning is used to increase the amount of storage capacity of an array.  As an example: if three 100 gigabyte hard drives are configured as one spanned array, the result would be one logical drive 300 gigabytes in size.

Spanning alone provides no redundancy or fault tolerance and it is commonly combined with mirroring.

What is Mirroring?

Mirroring is the duplication of data onto two or more drives simultaneously to create data redundancy and increase fault tolerance.  A mirrored array sacrifices half of its storage capacity to achieve a redundant status.  If two 100 gigabyte drives are mirrored the result is a single 100 gigabyte mirrored array.

What is Striping?

Striping is a bit more complex.  Striping is used to increase performance.  This increase in performance is achieved by splitting the read and write data down into ‘blocks’ and then writing or reading that data simultaneously onto two or more physical drives on the same sector of each respective drive.

In a simplified example imagine that you are writing 100 megabytes of data out to a striped array.  If you were to take that data and split it into two 50 megabyte chunks and then write both of those chunks simultaneously, one 50 megabyte chunk to drive (a) and the other 50 megabyte chunk to drive (b), you would theoretically half the time required to perform the process.  That, in essence, is the theory behind striping.

Striping provides a significant increase in performance but it is also the most dangerous of all the RAID levels when used alone.  Not only is there no redundancy but if either or any of the drives in a striped array fails, all of the data from the entire array is completely lost.

RAID Level 0 

RAID Level 0 – (2 Drive Minimum – no Fault Tolerance) Block Level Striping without Parity or Mirroring:  Because this type of RAID offers no fault tolerance or redundancy it is technically not actually RAID.  Raid 0 offers the best performance of all the RAID levels.  Data is broken down into fragments called blocks and is then written to all drives in the ‘array’ simultaneously across what is called a ‘stripe’ (on the corresponding disks in the same sector).  When data is read it is broken down into smaller pieces which can be read in parallel thereby increasing bandwidth.  With RAID 0 if any drive fails all data is lost across the entire ‘array’.  Even at minimum the likelihood of a catastrophic loss is double that of a single drive without any RAID at all.  RAID 0 should never be used alone for critcal data.

RAID Level 1

RAID Level 1 – (2 Drive Minimum – Data Redundancy) Mirroring:  In its simplest form RAID 1 simply duplicates data onto two different hard drives simultaneously, thereby providing data redundancy.  Data redundancy means that if either of the two hard drives fails for any reason no data will be lost as there is an exact duplicate or ‘mirrored set’ of the data on the other drive.  Data integrity is maintained as long as either of the two hard drives in the array is functioning.  In the event that one of the drives does fail it is simply swapped out for a new working drive.  The ‘array’ then ‘rebuilds’ itself by duplicating all of the data onto the new drive and recreating the ‘mirrored set’.  Data is, however, vulnerable while a rebuild is in progress.

RAID Level 5

RAID Level 5 – (3 Drive Minimum – Redundancy Through Parity) Block-Level Striping with Distributed Parity:  RAID 5 combines the increased speed of striping with redundancy through distributed parity.  In RAID 5 one drive out of the array will always be sacrificed to achieve redundancy.  In other words, when there are three 100 gigabyte drives present in a RAID five, the array will be 200 gigabytes in size.  However, by using distributed parity, the redundancy is spread across the entire array.  Therefore, if any one drive in a RAID 5 fails, data integrity is maintained and an opportunity exists to replace the failed device and rebuild the array. 

RAID Level 6 

RAID Level 6 – (4 Drive Minimum – Redundancy Through Parity) Block-Level Striping with Double Distributed Parity:  Very similar to RAID 5, RAID 6 builds on the security of RAID 5 by adding an additional level of redundancy.  In a RAID 6 up to two drives can fail and no data will be lost.  RAID 6 makes very large arrays possible, where the time it takes to rebuild the array after a drive failure can be quite lengthy.  In a RAID 5 scenario data would be vulnerable for far too long while the rebuild is in progess.  RAID 6 addresses this concern by adding an additional redundancy drive.  RAID 6 is the solution that should be used where data is extremly critical or high system availability is important.

RAID Level 1+0

RAID Level 1+0 – (2 Drive Minimum (though 4 are more commonly used) – Redundancy Through Mirroring) Mirrored Sets in a Striped Set:  Fault tolerance and increased performance.  This RAID level is a combination of RAID 1 (mirroring) and RAID 0 (striping).  RAID 1+0 can sustain multiple drive failures as long as no mirror loses all of its drives.

RAID Level 0+1

RAID Level 0+1 – (4 Disk Minimum; must be even number of drives – Redundancy Through Mirroring) Striped Sets Mirrored:  Here, a second striped set is created to mirror the first striped set.  In contrast to the 1+0, in RAID 0+1, all the drives in one mirror can fail without a data loss but if drives fail on both sides of the mirror everything on the entire array is lost.

San Antonio Data Recovery 

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Data Backup – The most effective way to prevent data loss is a solid data back-up procedure.  Critical data should be backed-up at least once daily or possibly even more often for very active file systems.  The Data Backup frequency will depend upon the rate at which the protected data is modified or updated.

Data Backup falls into three basic categories:

• Normal Backup. A normal backup copies all selected files and marks each file as having been backed up (in other words, the archive attribute is cleared). With normal backups, you need only the most recent copy of the backup file or tape to restore all of the files. You usually perform a normal backup the first time you create a backup set.
• Differential Backup. A differential backup copies files created or changed since the last normal or incremental backup. It does not mark files as having been backed up (in other words, the archive attribute is not cleared). If you are performing a combination of normal and differential backups, restoring files and folders requires that you have the last normal as well as the last differential backup.
• Incremental Backup. An incremental backup backs up only those files created or changed since the last normal or incremental backup. It marks files as having been backed up (in other words, the archive attribute is cleared). If you use a combination of normal and incremental backups, you will need to have the last normal backup set as well as all incremental backup sets in order to restore your data.

Normal Backup – Anytime that a new backup procedure is initiated a ’Normal’ backup must first be created before ‘Incremental’ or ‘Differential’ backups become possible.  A ‘Normal’ backup copies all of the selected files and stores a complete copy of them in the destination backup set.  Therefore, to perform a restore from a ‘Normal’ backup you need nothing more than the most recent ‘Normal’ backup set to restore every file that has been backed up.

So you may ask, what is the point of the ‘Differential’ and ‘Incremental’ backup options.  Well, it comes down to speed and storage space.  A ‘Normal’ backup can take quite a long time to perform depending on the amount of data that is being backed up as well as use a very large amount of storage space.

Differential Backup – The ‘Differential’ backup looks at the data that is stored in the last ‘Normal’ backup and compares it to the state of the data in the current system and then stores only that data that has changed in the interim.  In the typical computer environment, the ratio of the data that changes each day to the data that remains static is somewhere on the order of 1 to 2 percent.  Therefore, the size of the ‘Differential’ backup is fractionally tiny in comparison to a ‘Normal’ backup and the time it takes to generate and store a ‘Differential’ backup is minimal compared to the time it would take to create another ‘Normal’ backup set.  However, a ‘Differential’ backup set, in and of itself, is of no value.  To perform a data restore from a ‘Differential’ backup, both the original ‘Normal’ backup set as well as the ‘Differential’ backup set are required.

Incremental Backup – The ’Incremental’ backup looks at the data that is stored in the last ‘Normal’ backup set and also the changes that have been saved in the last ‘Incremental’ backup set and then compares that information to the current state of the system, storing only that data that has changed in the interim.  This type of backup uses even less storage space and theoretically can be done even more frequently (even hourly).  The biggest drawback to this type of backup is that to perform a data restore using this method you need the original ‘Normal’ backup set and all of the incremental backup sets as well.

A solid back-up procedure would normally be comprised of a combination of a periodic ‘Normal’ backup (maybe weekly or monthly) and either daily ‘Incremental’ or daily ‘Differential’ backups.  The reason periodic ‘Normal’ backups need to be performed is because of the fact that over time the ‘Differential’ backup sets grow larger and larger and take longer and longer to create.  In the case of the ‘Incremental’ backup, as time passes the number of backup sets continues to increase each time a backup is executed.  Performing a fresh ‘Normal’ backup allows this process to start over.

Every system configuration should include some form of Data Backup:

We know that your data is important to you.  A Data Backup plan is inexpensive and should be part of every basic system configuration.

We also offer data transfer to an external hard drive, USB drive or other Digital Media.   We can also migrate your data to a different computer if you would like.

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CD/DVD Data Recovery is not always possible in all scenarios but in the majority of cases significant recovery is usually possible if the attempt to recover the lost data is made soon after the data loss occurs.

In every case the sooner the affected storage media is brought in for analysis the better the odds are that a recovery can be made.  Even in the worst case scenarios partial recovery should be possible.

Typical types of data recovered includes but is not limited to:  pictures, music, videos, spreadsheets, databases, letters, and documents of all types.

The sooner you attempt to recover the lost data the better.  The more time that passes when you have a worn or scratched CD/DVD the more difficult it will be to recover 100% of the data.

Find out how our team of San Antonio Data Recovery specialists can help recover your critical data.  210-260-0045.

San Antonio Data Recovery

San Antonio Hard Drive Recovery

San Antonio File Recovery

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Data recovery and/or file recovery is not always possible in all scenarios but in the majority of cases significant recovery is usually possible if the attempt to recover the lost data is made soon after the data loss occurs.  Data can be lost in many different ways, the most typical are:

• Accidental deletion, erasure or format.
• Malicious or intentional deletion, erasure, or format.
• Operating system failure or software crash.
• Physical damage to storage medium, ie. scratched CD/DVD.
• Physical Hard Drive failure or crash.  Catastrophic hardware failure.

Typically the most severe data loss occurs with a catastrophic hardware failure.  This type of loss is usually the most complete and by far the recovery attempt is the most costly.  Thankfully, hardware failure is the least common type of data loss.

Simple accidental deletion is by far the most common form of data loss, and in most cases if the affected storage device is brought in immediately following the incident there is a near 100% recovery rate.

Malicious destruction occurs when data is intentionally destroyed or deleted, and the effectiveness of any recovery attempt from this type of loss is completely dependent upon the skill and thoroughness of the person responsible for the data destruction.  Recovery from this type of loss can range from a 100% full recovery, to a 0% total loss, depending upon the techniques that were used to destroy the data.

In every case the sooner the affected hardware is brought in for analysis the better the odds are that a recovery can be made.  Even in the worst cases, at minimum, partial recovery should be possible.

Typical types of data recovered includes but is not limited to:  pictures, music, videos, spreadsheets, databases, letters, and documents of all types.

We offer FREE hard drive or storiage media evaluation. Find out how our team of San Antonio Data Recovery specialists can help recover your critcal data.  210-260-0045.

San Antonio Data Recovery

San Antonio Hard Drive Recovery

San Antonio File Recovery

San Antonio Laptop Repair

Digital Media Data Recovery is not always possible in all scenarios but in the majority of cases significant recovery is usually possible if the attempt to recover the lost data is made soon after the data loss occurs.  Data can be lost in many different ways, the most typical are:

• Accidental Deletion, Erasure or Format.
• Operating System Failure or Software Crash.
• Virus or Spyware Infection.
• Malicious or Intentional Deletion, Erasure, or Format.
• Physical Damage to Storage Medium, ie. Storage Media Has Been Exposed to Liquids.
• Digital Media Device Experiences a Data Corruption Error.

Simple accidental deletion is by far the most common form of data loss.  In most cases if the affected storage device is brought in immediately following the incident there is a near 100% recovery rate.

The next most common data loss occurs when there has been an Operating System Crash or System Crash.  In this scenario chances are good that the data is still intact on the device, though it may not be accessible in the standard way.  A near full recovery should be possible in the majority of cases.

Virus and Spyware infections can also cause system failures and data destruction.  Data recovery in this instance varies depending upon how much damage has occurred.

Malicious destruction occurs when data is intentionally destroyed or deleted.  Once again, a data recovery in this case will vary depending upon the skill and thoroughness of the person responsible for the data destruction.  Recovery from this type of loss can range from a 100% full recovery, to a 0% total loss, depending upon the techniques that were used to destroy the data.

In every one of these cases, the sooner the affected hardware is brought in for analysis the better the odds are that a recovery can be made.  Even in the worst case scenarios, partial recovery should be possible.

Typical types of data that can be recovered include but are not limited to:  pictures, music, videos, spreadsheets, databases, letters, and documents of all types.

The first thing you must do is immediately power down your equipment.  After you have powered your system down, remove the flash drive and place it in a safe dry environment until you can contact a data recovery service.  Using your flash drive for any other activity can permanently modify and/or destroy your data. This is the single most important step to minimizing the amount of damage incurred in a data loss scenario.

Find out how our team of San Antonio Data Recovery specialists can help recover your critical data.  210-260-0045.

San Antonio Data Recovery

San Antonio Hard Drive Recovery

San Antonio File Recovery

San Antonio Laptop Repair

• Accidental Deletion, Erasure or Format.
• Operating System Failure or Software Crash.
• Virus or Spyware Infection.
• Malicious or Intentional Deletion, Erasure, or Format.
• Physical Damage to Storage Medium, ie. Scratched CD/DVD.
• Physical Hard Drive Failure or Crash.  Catastrophic Hardware Failure.

Simple accidental deletion is by far the most common form of data loss.  In most cases if the affected storage device is brought in immediately following the incident there is a near 100% recovery rate.

The next most common data loss occurs when there has been an Operating System Crash or System Crash.  In this scenario chances are good that the data is still intact on the hard drive, though it may not be accessible in the standard way.  A near full recovery should be possible in the majority of cases.

Virus and Spyware infections can also cause system failures and data destruction.  Data recovery in this instance varies depending upon how much damage has occurred.

Malicious destruction occurs when data is intentionally destroyed or deleted.  Once again, a data recovery in this case will vary depending upon the skill and thoroughness of the person responsible for the data destruction.  Recovery from this type of loss can range from a 100% full recovery, to a 0% total loss, depending upon the techniques that were used to destroy the data.

Typically the most severe data loss occurs when a system experiences a catastrophic hardware failure.  Because this type of data loss involves physical damage to the hard drive, in some cases portions of the hard drive can be rendered completely unreadable.  To recover data from a physically damaged hard drive requires very specialized equipment and techniques which means that this type of data recovery can be fairly costly.  Thankfully, hardware failure is the least common type of data loss.

In every one of these cases, the sooner the affected hardware is brought in for analysis the better the odds are that a recovery can be made.  Even in the worst case scenarios, partial recovery should be possible.

Typical types of data that can be recovered include but are not limited to:  pictures, music, videos, spreadsheets, databases, letters, and documents of all types.

• Logical Failure: The hard drive is mechanically sound – it spins correctly, the operating system recognizes the device, and all of the mechanical parts inside of the hard drive are functioning correctly. However, there is some reason that the data cannot be accessed through ordinary means. (This can include: accidental deletion or format, data corruption, operating system crash, or miscellaneous lost partitions or boot records.)
• Mechanical or Physical Failure: The hard drive is somehow physically damaged. Some internal part within the hard drive is no longer functioning correctly. The hard drive may make clicking noises or is not recognized by the operating system any longer. (This can be a hard drive crash or control board failure.)

• Logical Failure: The lost data is most likely still intact on the hard drive unless new data has been written over it. When a file is deleted or the drive is formatted, the data is not actually removed; the area where the data was stored is simply reallocated for new data storage and the file pointers are reset.
• Mechanical or Physical Failure: The data may still be intact on the hard drive platters but is not accessible due to some mechanical malfunction. Recovering data from a physically damaged hard drive is a very delicate operation and needs to be performed using specialized equipment and processes.

In the case of either a logical failure or a physical failure there is a good chance that data can be recovered successfully if the attempt to recover the data is made immediately after the data loss occurs.

The first thing you must do is immediately power down your equipment.  Continuing to use your system after a data loss for any other activity, even browsing the Internet, can permanently modify and/or destroy your data. This is the single most important step to minimizing the amount of damage incurred in a data loss scenario.

Find out how our team of San Antonio Data Recovery specialists can help recover your critical data. 210-260-0045.

San Antonio Data Recovery

San Antonio Hard Drive Recovery

San Antonio File Recovery

San Antonio Laptop Repair