Data recovery from RAID 0, 1, 5, 6, 10 and other configurations. Hardware and software RAID, standard and enterprise arrays. Years of experience, in-house laboratory, express service.
RAID data recovery is among the more complex disciplines in the data recovery field. Each RAID configuration has its specifics — a different way of storing data, varying levels of redundancy and different behaviour when one or more drives fail. At the EXALAB laboratory, we have been recovering data from RAID arrays since 2006 and have experience with all common and uncommon configurations, from simple two-drive arrays to large enterprise storage systems with dozens of drives.
Our long-term RAID data recovery success rate is approximately 95%. Diagnostics are free and non-binding. We keep most spare parts in stock; express service is available outside business hours.
Consultation, diagnostics and courier pickup are always free of charge.
Symptoms:
This is the most common cause of RAID data loss. Drives in servers and NAS devices typically run around the clock and are subjected to higher thermal and mechanical stress than drives in desktop computers. Failure may be caused by wear, manufacturing defects, damaged platter surfaces or head failure (HDD), controller or firmware failure (SSD), or electrical damage from a short circuit or power surge. The price depends on the number of drives, RAID configuration, type and extent of damage, and whether the array was manipulated after failure. We will provide an exact quote after free diagnostics. You only pay for successful data recovery.
Indicative price: from 10,000 CZK
More information — drive failures in RAID arrays
Free consultation, diagnostics, courier pickup
Symptoms:
A RAID controller can fail like any other electronic component — through wear, a dead cache backup battery (BBU/FBWC), firmware failure or electrical damage. When a hardware RAID controller fails, array metadata are stored on both the controller and the drives. Simply replacing the controller with an identical model may not work — especially if the firmware version differs or if on-disk metadata have been corrupted. Contact us for a free consultation.
Indicative price: from 3,000 CZK
More information — RAID controller failure and its consequences
Free consultation, diagnostics, courier pickup
Do not initiate a rebuild unless you are absolutely certain of the failure cause! You may turn a recoverable situation into a complicated one — or worse…
Symptoms:
A failed rebuild is one of the most common causes of RAID data loss that we encounter. A RAID 5 rebuild typically occurs after a single drive failure. During the rebuild process, the remaining drives are under extreme load — their entire capacity is being read. If another drive fails at this point, redundancy is lost. A rebuild failure can also be caused by a power outage, a device firmware bug or human error — such as swapping slots or inserting drives in the wrong order. Pricing is determined on a case-by-case basis depending on the extent of damage.
Indicative price: from 5,000 CZK
More information — why rebuilds fail and how to prevent it
Free consultation, diagnostics, courier pickup
Symptoms:
RAID arrays in servers and NAS devices typically use file systems such as NTFS, ReFS, ext4, XFS, Btrfs or ZFS. The data structure is more sophisticated than on a regular desktop drive. The problem may be caused by a software error, unexpected shutdown, power failure, a drive failing at a level not visible externally, ransomware, or an accidental configuration change. Unprofessional manipulation of the array configuration or attempts to repair the file system directly on the array (fsck, chkdsk) can irreversibly worsen the situation.
Indicative price: from 3,000 CZK
More information — inaccessible volume on RAID
Free consultation, diagnostics, courier pickup
Symptoms:
When data has been deleted, it is critical to stop using the device. Every additional write reduces the chance of successful recovery. If an entire volume was formatted, recovery prospects depend on the file system type and whether new data was written after formatting. For ransomware attacks on server and network storage (Deadbolt, Qlocker, eCh0raix), recovery options depend on the specific malware variant and the extent of encryption. The cause may also be human error, a software bug or an accidentally executed script.
Indicative price: from 2,000 CZK
More information — recovering deleted data from RAID
Free consultation, diagnostics, courier pickup
Do not power on a damaged server or drives! Further attempts may cause irreversible damage.
Symptoms:
Do not attempt to power on or further manipulate the device or drives. Do not connect damaged drives to other devices. Contact us to discuss next steps. We provide free courier pickup across the Czech Republic and, by arrangement, from other EU countries.
Indicative price: case-by-case
Free consultation, diagnostics, courier pickup
Data recovery pricing
RAID data recovery requires detailed knowledge of the specific array configuration — how data is distributed, where parity is stored, how the array responds to a drive failure and how a rebuild operates. We handle all common and uncommon configurations:
RAID 0 (stripe) distributes data across two or more drives without redundancy. Failure of any drive in the array results in total data inaccessibility. RAID 0 data recovery is nevertheless possible in most cases, though it requires block-level stripe reconstruction.
RAID 1 (mirror) mirrors data across two or more drives. When one drive fails, data remains accessible from the other. Problems arise when both drives fail or when a file system error occurs at the logical level.
RAID 5 distributes data and parity across three or more drives. It tolerates the failure of one drive. This is one of the most widely used configurations in servers and NAS devices. Failure of two or more drives or a failed rebuild are among the most common cases we handle.
RAID 6 is similar to RAID 5 but with dual parity — it tolerates the failure of two drives simultaneously. It is used where higher resilience is required. Despite dual parity, we encounter failures that require professional intervention.
RAID 10 (1+0) combines mirroring and striping. It offers both high performance and redundancy. Problems arise when both drives in a mirror pair fail or when the controller malfunctions.
RAID 50 (5+0) and RAID 60 (6+0) are combinations used in larger enterprise environments with a higher number of drives. We also handle RAID 1E, RAID 3, RAID 4 and other less common variants. We have practical experience with every configuration.
In addition to standard RAID levels, we recover data from proprietary implementations: Synology SHR and SHR-2, Netgear X-RAID and X-RAID2, Drobo BeyondRAID, TerraMaster TRAID, RAID-Z1, Z2, Z3 (ZFS) and JBOD. Each of these implementations has a different approach to data management and redundancy, requiring specific recovery procedures.
The RAID implementation method affects the recovery process. We distinguish three main types:
Hardware RAID is managed by a dedicated controller with its own processor and memory (often with a battery to protect the write cache). Array configuration and metadata are stored on both the controller and the drives. When the controller fails, the metadata must be read directly and the array reconstructed from raw data — swapping in an identical controller does not always work and can worsen the situation in some cases.
Software RAID is managed by the operating system. On Linux, this most commonly involves mdadm (md RAID), LVM or ZFS. On Windows, Dynamic Disks and Storage Spaces. Metadata are stored directly on the drives, which generally simplifies reconstruction — the controller is not an obstacle. The file system and integrity of array metadata play the key role.
Pseudo-hardware RAID (FakeRAID) is a BIOS-level implementation using the motherboard chipset (e.g. Intel RST/VROC, AMD RAIDXpert). Metadata are partially proprietary and differ between platforms. We have experience reconstructing these as well.
Drives in servers and NAS devices typically operate around the clock. They are subjected to higher thermal and mechanical stress than drives in desktop computers. Even quality drives designed for RAID environments (NAS and Enterprise series) have a limited lifespan, and after several years of operation the probability of failure increases.
For mechanical drives (HDD), the most common causes are damaged platter surfaces, head failure, motor wear or electronics failure. For SSD in RAID environments, we encounter drive controller failure, NAND flash chip wear or firmware errors.
A common scenario is a RAID controller ejecting a drive from the array even though the drive is physically mostly functional. The cause is typically exceeding the permitted response time limit. Enterprise and NAS drives feature TLER (Time-Limited Error Recovery) or a similar function — if the drive encounters a bad sector, it has a limited time (typically 7 seconds) to attempt to read it. If it fails, the controller marks the drive as faulty and removes it from the array. Standard desktop drives lack this feature and may spend tens of seconds attempting to read a bad sector, paralysing the entire array. This is one of the reasons why it is important to use RAID-rated drives (NAS or Enterprise series) in RAID environments.
Using SSD in RAID arrays introduces specific risks. NAND flash memory chips have a limited number of write cycles, and drives from the same production batch installed at the same time may reach this limit at roughly the same time — creating a risk of synchronous failure of multiple drives at once. Some SSDs transition to read-only mode when write cycles are exhausted or when the controller fails; others stop responding entirely. Another risk is the TRIM command (UNMAP for SAS drives) — once the operating system marks data as deleted, the SSD controller irreversibly erases the underlying cells in the background as part of the Garbage Collection process. Recovering deleted data from SSD in a RAID array is therefore significantly more difficult than from an array with mechanical drives and requires immediate action.
A particularly dangerous situation occurs when two or more drives in an array fail within a short time of each other. This happens more often than one might expect — drives from the same production batch installed at the same time tend to have a similar lifespan and may begin failing at approximately the same time. We therefore recommend combining drives from different production batches in RAID arrays and regularly monitoring their condition via S.M.A.R.T. diagnostics.
Free consultation, diagnostics, courier pickup
Pricing — drive failures in RAID
A hardware RAID controller (e.g. Dell PERC, HP SmartArray, LSI MegaRAID, Adaptec) stores array configuration metadata both in its own memory and on the drives. When the controller fails, the seemingly simple solution is to swap in an identical model. In practice, however, this carries risks.
If the firmware version of the new controller differs, it may misinterpret the metadata on the drives. In the worst case, the new controller may overwrite the metadata with new values, destroying the original configuration. Another risk is that the controller failure is merely a symptom — the actual problem may lie with the drives themselves.
At our laboratory, when a controller has failed we bypass it and work directly with the drives. Based on metadata and data structure analysis, we reconstruct the array without depending on any specific controller. This approach is safer and eliminates the risk of data being overwritten by a new controller.
Free consultation, diagnostics, courier pickup
Pricing — RAID controller failure
A rebuild (reconstruction) of a RAID array is a process in which data on a newly inserted drive is recalculated from the remaining drives in the array. For RAID 5, this involves parity reconstruction; for RAID 1, mirror synchronisation. This process places extreme demand on the remaining drives — their entire capacity is read, which can take hours to tens of hours for large arrays.
It is during the rebuild that the array is most vulnerable. The remaining drives operate at full load, and a drive that previously showed only minor issues (incipient bad sectors) may definitively fail under this stress.
Statistically, for standard enterprise drives the probability of an Unrecoverable Read Error (URE) is approximately 1 in 1014 bits read, which corresponds to roughly 12.5 TB of data. When rebuilding an array with drives of 4 TB or more, the probability of at least one such error occurring on the remaining drives becomes significant. A single unreadable sector on a drive other than the originally failed one is enough for the rebuild to collapse. For RAID 5, this means complete loss of data access. For RAID 6, a single URE effectively reduces the array to RAID 5 protection — the second layer of redundancy is lost and any further error is fatal.
Rebuild failures can also be caused by other factors — a power outage, NAS or server firmware bug, human error (inserting a drive into the wrong slot, swapping drives). In some cases, an administrator initiates a rebuild on a device that worked fine under normal operation, but the increased load exposes hidden defects in the remaining drives.
How to minimise the risk: Regular S.M.A.R.T. monitoring, use of RAID-rated drives (NAS/Enterprise series with CMR recording), an uninterruptible power supply (UPS), and above all an independent data backup outside the RAID.
Free consultation, diagnostics, courier pickup
Pricing — failed RAID rebuild
A data partition (logical volume) on a RAID array is a technologically more sophisticated construct than what a user would encounter on a regular desktop drive. Data is distributed across multiple physical drives, and the volume may use a file system that standard desktop tools cannot even read (XFS, Btrfs, ZFS, VMFS).
If a volume becomes inaccessible and the cause is not immediately apparent, it may be file system corruption (for example after an unexpected power failure), a hidden failure of one of the drives, or a software error in the device itself. In some cases, ransomware may be to blame.
Running file system repair tools (fsck, chkdsk, btrfs check) directly on the original drives is risky. These tools may make metadata changes that worsen the situation. At our laboratory, we always create binary copies of all drives first and only then proceed with analysis and reconstruction.
Free consultation, diagnostics, courier pickup
Pricing — inaccessible partition on RAID
Recovering deleted data from a RAID array is in many respects similar to recovering deleted data from a regular drive, but with greater technological complexity. Data is stored across drives in a distributed manner, and the RAID logical volume must first be reconstructed before individual file recovery can begin.
With copy-on-write file systems (Btrfs, ZFS), the chance of recovery may be higher because data is not overwritten in place. Conversely, with traditional file systems (NTFS, ext4, XFS), success depends on whether new data was written to the locations previously occupied by the deleted files.
For ransomware attacks on network storage (Deadbolt, Qlocker, eCh0raix and others), recovery options depend on the specific malware variant, whether the encryption was completed, and the storage file system. In some cases, data can be restored from previous snapshots or older file versions, if the device supported them.
The key rule: after data deletion, stop using the device and do not shut it down in the normal way (to prevent internal housekeeping processes from running) — instead, disconnect the power and contact us.
Free consultation, diagnostics, courier pickup
Pricing — deleted data from RAID
In RAID data recovery, we encounter a wide range of hardware. We are experienced in reconstructing arrays from controllers of all major manufacturers:
RAID controllers: Adaptec (Microchip), LSI / Broadcom (MegaRAID), Dell PERC, HP / HPE SmartArray, Intel RAID (RST, VROC), Areca, 3Ware, Promise, ATTO, HighPoint, ICP Vortex, QLogic and others.
Servers: Dell PowerEdge, HP / HPE ProLiant and Synergy, Lenovo ThinkSystem, IBM Power and xSeries, Supermicro, Fujitsu PRIMERGY, Cisco UCS and others. We also handle DAS and SAN storage from NetApp, Dell EMC, HP StoreEasy and other manufacturers.
If you do not see your controller or server listed, do not hesitate to contact us — we very likely have experience with your specific platform.
We recover data from all file systems used in RAID environments:
Windows: NTFS, ReFS, FAT32, exFAT
Linux: ext2, ext3, ext4, XFS, Btrfs, ZFS (OpenZFS), JFS, ReiserFS
macOS: HFS+, APFS
Virtualisation: VMFS (VMware vSphere)
Other: UFS, GPFS (IBM Spectrum Scale)
1. Consultation and Intake
Contact us by phone, email or through our online form. We will assess the situation together. We provide free courier pickup of drives or the entire device across the Czech Republic and, by arrangement, from other EU countries.
2. Diagnostics
We perform a thorough diagnostic of all drives from the array. We test their condition, read the RAID configuration metadata and evaluate recovery options. Diagnostics are free and non-binding — you will receive a report with a description of the condition, pricing and an estimated turnaround time.
3. Data Recovery
First, we create binary copies of all drives (sector-by-sector imaging) using hardware write blockers that physically prevent any writes to the original drives. If a drive is mechanically damaged (failed read heads, damaged platter surface), the repair is carried out in the clean room of our laboratory prior to cloning. Only then do we proceed to reconstruct the RAID configuration and recover data from the copies — the original drives are stored safely throughout and are never subjected to further stress.
4. Data Handover
Upon completion, you receive a list of recovered files. Data is delivered on new media (external drive, encrypted transfer). You pay only for successfully recovered data.
After receiving the drives, we perform free diagnostics — testing the condition of each drive and reading the RAID configuration metadata. We then create binary copies of all drives (sector-by-sector cloning). Based on these copies, we reconstruct the RAID array and recover the data. The original drives are not subjected to further stress during recovery. A detailed description is available in the How RAID Data Recovery Works section.
The price depends on the failure type, array configuration, and the number and condition of drives. Indicative prices are listed in the failure type overview. We provide an exact quote after free diagnostics. We offer several processing speed options, from standard to express — faster is more expensive, slower is more affordable. You only pay for successfully recovered data.
Turnaround time depends on the number and condition of drives, the array configuration and the chosen service tier. For less severe cases, it is typically a matter of days; for complex cases with mechanically damaged drives, it may take several weeks. Express service is available outside business hours. A specific estimate is provided as part of our free diagnostics.
Ideally, yes — including drives that appear completely non-functional. Each drive in the array contains a portion of the data and configuration metadata. For RAID 5 or 6, it is theoretically possible to reconstruct data without one or two drives respectively, but having all drives significantly increases the chance of complete recovery and reduces processing time.
Only if you are absolutely certain that only one drive has failed and the remaining drives are healthy. In practice, it is common for multiple drives to show early signs of failure, and the increased load during a rebuild can cause another drive to fail. If you have any doubts, we recommend consulting professionals before starting a rebuild. A failed rebuild is one of the most common cases we handle in our laboratory.
Software tools for RAID reconstruction do exist (R-Studio, UFS Explorer, ReclaiMe and others). These tools can help with purely logical failures where all drives are physically healthy. However, if the cause of failure is hardware-related, attempting software recovery directly on the original drives can irreversibly damage the data. The safer path for valuable data is to entrust the case to a professional laboratory that first creates safe copies of the drives.
In some cases, replacing a controller with an identical model running the same firmware version can work. However, there is a risk — a different firmware version or corrupted on-disk metadata can lead to a state where the new controller fails to initialise the array correctly or, worse, overwrites the metadata with new values. We recommend consulting an expert before attempting this. More in the RAID Controller Failure section.
Yes, in most cases RAID 0 data recovery is possible, even though RAID 0 offers no redundancy. If one drive is non-functional, recovery depends on whether data can be read from that drive (at least partially). From the functional drives, the stripe can be reconstructed and files for which all required data is available can be recovered.
No. RAID protects against the failure of one or more drives (depending on the configuration), but it does not protect data from deletion, ransomware, controller failure, software errors or natural disasters. RAID should always be complemented by an independent backup at a separate physical location.
Regularly monitor drive health (S.M.A.R.T. monitoring). Replace failing drives promptly. Use drives designed for continuous RAID operation (NAS/Enterprise series, CMR recording technology). Consider a UPS for protection against power outages during operation and rebuilds. Most importantly — back up your data independently of the RAID. The proven 3-2-1-1 backup strategy recommends keeping three copies of data on two different media types, one copy off-site and one copy on offline or immutable (WORM) storage that even administrators cannot modify. This last layer is the critical defence against ransomware attacks, which can encrypt all online-accessible storage including network backups within hours.
Wrap each drive individually in an anti-static bag and cushion them with soft material to prevent impacts. Label the drive order by slot number (slot 0, 1, 2…). If possible, send the entire device (server, NAS) with drives in their original positions. We provide free courier pickup across the Czech Republic.
Hardware RAID is managed by a dedicated controller (PCIe card) with its own processor and memory. Software RAID is managed by the operating system (Linux mdadm, ZFS, Windows Dynamic Disks). Hardware RAID typically offers higher performance and OS independence, but recovery can be more complex when the controller fails. Software RAID is more flexible and its metadata are stored directly on the drives, which simplifies reconstruction. More details in the Hardware RAID vs. Software RAID section.
Confidentiality and treating all data as sensitive is a matter of course for us. If the nature of the project requires it, do not hesitate to request a formal non-disclosure agreement (NDA). RAID arrays and servers often contain business data, databases and accounting systems — we understand this and handle them with appropriate care.
Is your data insured? Before you confirm the order, we will prepare a "fault confirmation" document, which you can submit to your insurance provider for cost approval before proceeding.
EXALAB Data Recovery
Microshop s.r.o.
Pod Marjánkou 4
169 00 Praha 6
Česká Republika
Opening hours:
Monday to Thursday
9.00 - 18.00
Friday 9.00 - 17.30
other opening hours are possible upon agreement
Hotline: +420 608 177 773
Office: +420 233 357 122
E-mail: info@exalab.cz
Hotline: +420 608 177 773
Kancelář: +420 233 357 122
E-mail: info@exalab.cz
Opening hours:
Monday to Thursday
9.00 - 18.00
Friday 9.00 - 17.30
other opening hours are possible upon agreement
EXALAB Data Recovery
Microshop s.r.o.
Pod Marjánkou 4
169 00 Praha 6
Česká Republika
