RAID 5 Recovery

RAID 5 data loss? How to prevent consequential damage

• Keep calm in case of RAID 5 failure. High pressure situations like that may come with hasty actions and irrational decisions. Therefore it is crucial to keep calm in order to prevent consequential damage. Our experience shows: The more recovery tries were made before contacting us, the more effort is needed in order to recover your needed data.

• Never swap two hard drives at the same time. If two hard drives of a RAID 5 array are swapped simultaneously, the rebuild cannot be executed properly. In the worst case a multitude of the data can subsequently be inconsistent. But even with such cases, our technicians can help you with the RAID 5 data recovery.
• Forcing RAID 5 online? You only have one attempt! Forcing a RAID 5 online can bear great risks. Be aware that you only get one attempt. All parameters have to be correct, in order to prevent corrupt data. Not only the correct order of the hard drives is crucial. You also should be a 100% certain, that no hard drive failed before and the system wasn't running in degraded mode.

Is your RAID 5 offline? Common reasons for data loss!

Three or more hard drives fail at the same time

The failure of at least two hard drives at the same time result in an offline RAID 5. This can happen after a blackout. Even server, that were in 24/7 use for a long period of time and were shut down correctly can be affected by a RAID-failure after a reboot. This is particularly risky, if one hard drive failed a while ago and wasn't replaced. The array runs in degraded mode until a second hard drive fails.

RAID 5 rebuild cancelled

One of the most frequent causes for data loss from RAID 5 systems is a cancelled rebuild. All of the sectors of every hard drives are being accessed and even one read error can lead to an ejection of the affected hard drive out of the RAID 5 array.

RAID 5 controller is defective

A defective RAID 5 controller can lead to a failure of the array. Common reasons are bugs, firmware errors or faulty software.

General information to RAID 5 - Redundancy of RAID 5

RAID 5 is the most popular RAID type, thanks to the high data throughput and performance with relatively low costs. RAID 5 is one of the cheapest options for saving data redundantly on more than one hard drive with a highly efficient storage capacity.

RAID 5 distributes the user data in blocks, but without a determined parity drive. The XOR data and the user data are distributed equally on all the hard drives. At the same time the mechanical load is distributed equally as well, because none of the hard drives has a special position within the parity drive.

Data safety is guaranteed thanks to redundancy. If one hard drive fails during a rebuild on a previously installed hot spare drive, the performance decreases. That's the so-called "degraded mode", when the RAID 5 is temporarly not protected against the failure of a second hard drive - no matter if SCSI, SAS or SATA.