When a RAID array fails it's not because they are designed to fail, something goes wrong, be it accident or disaster.
But for a large scale RAID 5 array to fail is unusual but it does happen. Often storage infrastructure managers are not aware how data corruption can creep into a RAID at the block level.
In the lab we see the effects on a daily basis from a 3 Disk drive configuration right up to 22 or even 55 disk members arriving at the Security House lab and onsite upto a 180 disk arrays.
Non are designed to fail but they do. In some situations what starts as one bad drive can lead to a complex mess and missing data even within VMs and databases.
Multiple failed / swapped drives later and more keep failing each time new ones are added to resync. Despite the resilience of the RAID, data to corruption can creep in despite monitoring software giving no indication of drive errors.
If it's a pointer to your situation and how as a data recovery lab we see the consequences of picking the wrong model / class of drives - over 70% of our work in DR is thanks to non enterprise class Seagate hard drives .
Some DR labs are also Seagate partners because they do not have the capabilities we have and they still cannot recover in lab what R3 engineers can.
R3 don't use Seagates in their servers or imaging process except for 8TB at the moment but that's not to say Seagates are bad drives, it a combination of factors, market share, brand loyalty, low cost, extended warranty, but they do develop problems.
R3 currently have over 500 1TB to 6TB drives in use in the lab most are WD - Western Digital - A colourful mixture of Red, Green, White, Gold, Blue and Purple.
R3 do get bad sectors developing on them spotted during the imaging process or during the secure wiping process. Failing drives are pensioned off but they are worked hard and power cycled regularly as well a sure wiped after every recovery is completed. What you should not do is assume new storage technology or VM or SSD or cloud backup is the solution it's not.
If you need help checking the integrity of your data or run into problems with any loss of data get in touch with R3s disaster and data recovery specialists. R3 Data Recovery Ltd has a staff of 25 with 8 Full time engineers and their assistants recovering data 7 days per week for clients across the UK and internationally