Please help with RAID 5

[Edds]

I have 5 hdd with 36 Gb logical memory (each), and I lock them in RAID 5, what would be massive logical memory?
Please help....

 

[muckshifter]

RAID 5 is seen by many as the ideal combination of good performance, good fault tolerance and high capacity and storage efficiency. It is best suited for transaction processing and is often used for "general purpose" service, as well as for relational database applications, enterprise resource planning and other business systems. For write-intensive applications, RAID 1 or RAID 1+0 are probably better choices (albeit higher in terms of hardware cost), as the performance of RAID 5 will begin to substantially decrease in a write-heavy environment.

If your using RAID on a home PC then you is just wasting your time.

If you're in a business environment ... then get the pros in.

 

[ChristopherP]

OI - i use RAID0 in my PC, its good

RAID Level 5

Common Name(s): RAID 5.

Technique(s) Used: Block-level striping with distributed parity.

Description: One of the most popular RAID levels, RAID 5 stripes both data and parity information across three or more drives. It is similar to RAID 4 except that it exchanges the dedicated parity drive for a distributed parity algorithm, writing data and parity blocks across all the drives in the array. This removes the "bottleneck" that the dedicated parity drive represents, improving write performance slightly and allowing somewhat better parallelism in a multiple-transaction environment, though the overhead necessary in dealing with the parity continues to bog down writes. Fault tolerance is maintained by ensuring that the parity information for any given block of data is placed on a drive separate from those used to store the data itself. The performance of a RAID 5 array can be "adjusted" by trying different stripe sizes until one is found that is well-matched to the application being used.

 

[Techy]

I just don't understand the question???

 

[ChristopherP]

Im guessing he means what amount of storage will he have in windows with a RAID 5 array consisting of 5x 36Gb drives...

 

[Adywebb]

Im guessing he means what amount of storage will he have in windows with a RAID 5 array consisting of 5x 36Gb drives...

And the answer is.........................?

 

[CITech]

And the answer is.........................?

144GB of usable disc space !

(Give or take a few Gig for the old byte/bit arguement)

 

[Adywebb]

144GB of usable disc space !

(Give or take a few Gig for the old byte/bit arguement)

Ok, for my benefit - 144Gb is 4 x 36GB HD's, as its a stripe array and not a mirror, why is it not 5 x 36GB = 180GB Total??

 

[CITech]

OK, quick explanation. Your maths is correct, except you haven't taken into account how the RAID5 maps the data across the drive array.

RAID5 works by using a minimum of 3 identical discs and writes the data with parity (I think) so that any one of the drives can be removed without causing the overall array to crash. You can add as many identical discs as you want (within reason) and you still only need the one "surplus" disc to provide the RAID facility.

Therefore, in theory, you could have 6 x 200GB HDDs arranged in such a way as to give you a 1TB usable disc, with the safety of being able to lose any ONE drive without losing the data. However, you should always bear in mind that using big discs such as 100GB+ will mean big rebuild times one you have installed the replacement device.

Also, you can't add additional drives to the array without rebuilding the whole configuration.

Hope this helps. If not, feel free to shout again.

CI

 

[Adywebb]

Yep - clear as mud

No really, makes sense to me - thanks CI

 

[CITech]

My pleasure, RAID systems are one of my babies so anytime you got a problem .... ring my local pub and ask them to find me

 

[muckshifter]

ain't it nice to have someone who knows his RAID

My pleasure, RAID systems are one of my babies so anytime you got a problem .... ring my local pub and ask them to find me

That's on ... 01534 482116

 

[Adywebb]

That's on ... 01534 482116

All I get is the answering machine for 'The Amazing Maze and Adventure Park' in Jersey Mucks

Bet you knew someone would try it

 

[ChristopherP]

a'Maizin Maze lol

 

[muckshifter]

All I get is the answering machine for 'The Amazing Maze and Adventure Park' in Jersey Mucks

And your question is ... ?






* I like mazes *

 

[psd99]

lmao!!!

 

[CITech]

That's on ... 01534 482116

Wrong Island my friend - I'm in Guernsey (not the one where they filmed Bergerac), and you need to look up the "Cock & Bull". Then you might get lucky

 

[muckshifter]

Wrong Island my friend - I'm in Guernsey (not the one where they filmed Bergerac), and you need to look up the "Cock & Bull". Then you might get lucky

Are we on about the Film (BBC), or the Club at St. Peter Port ... 01481 722660 for the "Cock & Bull" @ St. Peter Port.

Not sure on the film ...

 

[CITech]

Are we on about the Film (BBC), or the Club at St. Peter Port ... 01481 722660 for the "Cock & Bull" @ St. Peter Port.

Not sure on the film ...

Right number Mucks! The landlord (Billy) is going to love this free advertising Bet I still don't get a free drink though

 

[muckshifter]

Right number Mucks! The landlord (Billy) is going to love this free advertising Bet I still don't get a free drink though

I'll give him a tinkle later and get one put behind the bar for you ... does they take PayPal ...