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Calculating the failure rate of RAID 0

Calculating the failure rate of RAID 0
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In the pursuit of a high performance Server, PC or Laptop we should consider carefully why RAID 0 (RAID Zero) should only be used if combined with a suitable backup solution .

Anyone who relies on  computers, servers or laptops will try to get the best 
performance from them to maximise productivity,  but safety of data and system stability has for most to be the priority.

Generally the slowest part of the system is the ability to read and write data to disk.

Today when transferring terabytes of  data every hour even with 10gigabit network transfer speeds and multiple server arrays of 30 TB each in multiple
RAID 5 configurations it is still RAID 0 which offers the fastest read write cycles.
 
With many modern laptops and home computers now having  RAID 0  capability,  such performance enhancements are now mainstream,  once reserved for those who required any increase in a systems overall performance be it a server or high end gaming PC or powermac,  everyone now has access to RAID including network drives and external RAID storage devices with
burst transfer rates as high as 165MB/s (eSATA 3Gb/s) in RAID 0  .

Regardless of the theoretical transfer speed of a hard drive, real world performance will always rely on a number of factors, file fragmentation is one.

Without wanting to
explain RAID in detail , a RAID 5 array has built in redundancy which goes a long way to ensuring data integrity is maintained even in the event of the failure of one or more drives in the array.

RAID 1 is essentially a mirrored pair, which gives the chance that if one of the disk drives fail then the other can still be accessed but there is a speed penalty since both drives have to read and write the same data.

Conversely  RAID 0 which in its simplest form is a striped pair can be problematic. But we now have laptops with 
quad drive raid 0 The advantages are its speed when reading and writing data to the drives, the more drives in RAID 0 configuration the quicker the data is written across all the disks,  however since the data is spread across all the drives, should one drive fail completely a complete recovery of the data is impossible.

Many make best use of RAID 0 for its instantaneous data transfer advantages which can help improve computational  / cpu utilisation, but to prevent against data loss it would be sensible for the data to be backed up to a mirrored pair or even a RAID 5 array which in itself can affect system performance because of the extra data transfer overhead.

Failure to backup  a RAID 0 striped pair is a common problem and one I see on a daily basis in my data recovery lab and now with the advent of RAID 0, RAID 1 and even RAID 5  enabled Laptops these are now coming in on a regular basis.

 RAID 0 must have increased risk of data loss and increases the risk of needing a data recovery expert but to understand why you don't only need to be a maths  genius any gambler will understand why the odds of failure have increased.
Failed Server or RAID array ?

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Consider that the average failure rate of a hard disk drive is around 7% , with 600million drives sold every year, you will understand why the data recovery and data backup industry is as big as it is and why my data recovery lab is always so busy, but  a word of caution, do not assume SSD drives will save you they too can fail or be affected by power outages and the recovery of flash memory is an entirely different subject and cost implication,  RAID 0 can  regardless of the storage device type  fail for many reasons, mechanical failure, power outages, seized motors or media degradation, firmware and controller failure. Of course fire, flood and dropping a drive also contributes to disk failure rates.

So armed with this statistic we know that if you put 2 drives into RAID 0 then the chances of failure are essentially doubled, but the likelihood that both drives failing at the same instant is still very low unless an external catastrophe occurs.

So the calculation is  chances of RAID 0 failure =  storage device failure rate x number of drives in RAID 0  

Striped PAIR failure rate has increased to 14% 

Extrapolate this and create a 14 disk RAID 0  (hypothetical) storage volume and although your large files would likely be written to the disks very quickly,  the risk that the RAID would fail has increased dramatically .

Simply put the  calculation for the failure rate of a 14 Disk RAID 0 array would be   7% x 14 = 98% therefore the chances of any one drive in this array failing during its useful life has increased to almost 100% in other words its a ticking time bomb and your data is at risk unless you are creating a safe backup.

All disks are likely to fail eventually,  the MTBF (
Consider that the average failure rate of a hard disk drive is around 7% , with 600million drives sold every year, you will understand why the data recovery and data backup industry is as big as it is and why my data recovery lab is always so busy, but  a word of caution, do not assume SSD drives will save you they too can fail or be affected by power outages and the recovery of flash memory is an entirely different subject and cost implication,  RAID 0 can  regardless of the storage device type  fail for many reasons, mechanical failure, power outages, seized motors or media degradation, firmware and controller failure. Of course fire, flood and dropping a drive also contributes to disk failure rates.So armed with this statistic we know that if you put 2 drives into RAID 0 then the chances of failure are essentially doubled, but the likelihood that both drives failing at the same instant is still very low unless an external catastrophe occurs.So the calculation is  chances of RAID 0 failure =  storage device failure rate x number of drives in RAID 0   Striped PAIR failure rate has increased to 14%  Extrapolate this and create a 14 disk RAID 0  (hypothetical) storage volume and although your large files would likely be written to the disks very quickly,  the risk that the RAID would fail has increased dramatically .Simply put the  calculation for the failure rate of a 14 Disk RAID 0 array would be   7% x 14 = 98% therefore the chances of any one drive in this array failing during its useful life has increased to almost 100% in other words its a ticking time bomb and your data is at risk unless you are creating a safe backup.All disks are likely to fail eventually,  the MTBF (mean time between failure ) should not be assumed to be the  time a drive will survive under real world conditions.

Heat, transportation, earthquakes and human error all contribute to the failure rate, even under ideal conditions a HDD or SSD is degrading over time, so in a Striped pair (RAID 0) it is important to backup your data regularly on another drive, storage device or online backup.

However should a RAID 0 array fail on you never attempt a software recovery  without first seeking advice. Free advice is available from all good
data recovery companies .

If one drive in a RAID 0 array is degraded , seized,  has electronic faults or firmware corruption then a repair could still be
possible from which an image could be made,  the RAID 0 volume accessed and the the data recovered .