Storage Solutions Types Of RAID Failures

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te12345

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Most guys make this mistake of believing that once they have kept the data on RAID, then it is totally safe. But that is not true ! It is always advisable to keep at least one extra backup of important data, even if it is saved on RAID.

Please check the link for the complete material.

Common RAID Server Failure Types and Causes

Adroit Data Recovery Centre has handled a few hundreds of RAID data recovery cases throughout the years.

A large number of users had been made into believing that RAID should not fail, as a result of over emphasis of RAID's fault tolerance functions or auto rebuilt functions. As a result, up to date backups are seldom performed when the data disaster nightmare unfolds.

RAID may be implemented by hardware or software -based method, differentiated by the presence or absence of a RAID controller, Basically, a number of independent hard disks are connected to form a single and often larger virtual volume. Depending on the RAID configuration, there may be an increase in simultaneous reading and writing of drives along with the fault tolerance feature.

Popular RAID manufacturers such as Mylex, Adaptec, Compaq, HP, IBM etc. promotes the idea of extended data availability and protection when a failed hard disk was detected. In a typical RAID 5 configuration, without even power off, the RAID controller could rebuild the data volume from a hot standby drive or a replacement drive through hot swap. The only time it will fail is when two disks failed simultaneously but such probability is one in a million! As a result, one may tend to believe that RAID can not fail.
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raid 0 - stripe - no safety.
raid 1 - mirror - so two copies of same data.
raid 5 - parity - safety to some extent.
raid 10 - stripe+mirror - sripe the data and keep mirrors so more secure.

raid 10 is faster than raid 5. and it depends on how important your data is. people spend huge money on disaster recovery. thats where redundancy and highly available systems come into picture.
 
Raid 0 - full capacity of hdd but no redundancy
Raid 1 - 1/2 capacity of 2 hdd but data is duplicated hence redundancy is avail
Raid 5 - where out of 3 1 hdd capacity is lost as parity info is divided across physical disks can withstand only one hdd failure
Raid 10 - 2 spans of striped data are mirrored again in turn to provide both redundancy and performance , can withstand 1 hdd failure per span

Raid 6- 2 parity stripes are written and 2 hdd space is lost and can withstand 2 hdd failures
 
I have been in situations where a RAID5 has failed due to 2 disks dying.. Nothing is fool proof. Everything imp needs to be backed up.
 
Thanks for the replies @booo, @ryanrulez4ever and @djmykey.

When we look at the costs of disaster recovery and the risk that maybe the data might become unrecoverable in some cases, it becomes obvious why some people always prefer to keep multiple backups. That is a wise decision.
 
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