Need help with RAID design

Toggle sidebar Toggle sidebar
C

CMV

Honorable
Jan 31, 2014
16
0
10,510
You are given 4 hard disks, 1 Terabyte each, to build a RAID system. You should use all the 4 disks. Please explain your choice of the RAID level and the size of your RAID disk (the virtual disk presented by the RAID) under each of the 2 restrictions listed below:
• the maximum possible RAID disk size, or
• the best possible read/write performance.

 
Solution
ingtar33
I would probably build a RAID 10

It would be 2tb in size, double the speed of a single drive, and everything backed up for security.
Sort by date Sort by votes
WHComp

WHComp

Distinguished
Mar 13, 2010
106
0
18,710
If you don't mind losing half your storage, I would agree that RAID 10 is probably the best. Eliminates any parity calculations and will give you excellent read performance. However, you are losing half your storage space, and the write speed will only be twice as fast as a singe drive. (Write speed will be 4x as fast).

RAID 5 would give you 3TB of storage instead of 2, but the parity calculation does introduce some overhead. If you are using a hardware RAID controller the overhead will be very minimal, but if you are doing software RAID, the calculation can reduce performance.

Also, consider what you are using the volume for. If you are putting a SQL server on the volume you will want to stay away from RAID 5 all together.

Assuming you are using a Hardware RAID controller, here would be the difference between 5 and 10:

RAID 5: Size = 3TB, Write Speed = 3x, Read Speed = 3x
RAID 10: Size = 2TB, Write Speed = 2x, Read Speed = 4x
 
Upvote 0 Downvote
C

CMV

Honorable
Jan 31, 2014
16
0
10,510
OK so RAID 5 is optimal solution.


 
Upvote 0 Downvote
C

CMV

Honorable
Jan 31, 2014
16
0
10,510
I worked the solution for this as follows:
We learnt RAID 0 to 6 levels only.

RAID 1 -- Disk Mirroring
RAID 2 -- Bit Interleaved Redundancy
RAID 3 -- Bitwise Parity
RAID 4 -- Block Parity
RAID 5 -- Interleaved Parity Sectors
RAID 6 -- P+Q Redundancy

No of disks RAID level storage disks redundant disks efficiency
4 0 2 2 50%
4 1 2 2 50%
4 2 1 3 25%
4 3 3 1 75%
4 4 3 1 75%
4 5 3 1 75%
4 6 2 2 50%

So We need to choose between RAID 3, RAID 4 and RAID 5
If we choose RAID 3 /RAID 4/RAID 5 the maximum possible disk size is 3x 1TB= 3TB.

But I could not beyond that as I wasn't sure how reads and writes count are calculated. Please explain.
 
Upvote 0 Downvote
C

CMV

Honorable
Jan 31, 2014
16
0
10,510
But I had to choose between levels 0 to 6?


 
Upvote 0 Downvote
WHComp

WHComp

Distinguished
Mar 13, 2010
106
0
18,710
Are you using a hardware RAID controller? Or software? What is the model of the controller, I have not heard of a controller offering 0-6, that does not offer 10. I am not doubting you, I would just like to look at the specs on the controller to better answer your question. It really makes a huge difference when calculating the parity bit.

Also, what are you using the volume for?
 
Upvote 0 Downvote
C

CMV

Honorable
Jan 31, 2014
16
0
10,510
This task or assignment was given in our class. We just learnt only RAID 0, RAID 1, RAID 2, RAID 3, RAID 4 , RAID 5 and RAID 6 levels in our class. I have given a partial solution in this thread.


quotemsg=13213087,0,353362]Are you using a hardware RAID controller? Or software? What is the model of the controller, I have not heard of a controller offering 0-6, that does not offer 10. I am not doubting you, I would just like to look at the specs on the controller to better answer your question. It really makes a huge difference when calculating the parity bit.

Also, what are you using the volume for?[/quotemsg]

 
Upvote 0 Downvote
WHComp

WHComp

Distinguished
Mar 13, 2010
106
0
18,710
That is an absolutely horrible assignment. There are so many variables involved in choosing the "best" RAID configuration. It is like someone asking you "What is the best car". I really wish I could give you a definitive answer, but I don't know how. If there was one definitive best RAID configuration, then that would be the only option available. If you could say "RAID 5 is the best" then there would be no reason to offer all the other RAID types.

If I had to answer that question, I would say RAID 5. I can tell you that RAID 2, 3, and 4 are rarely if every used anymore. I have been working in IT services for 15 years, and I have never used any of those, or even come across them. I have only seen RAID 6 a couple times and it is a very niche option.

Tell your teacher they need to give you more variables to answer that question, like: Hardware or Software? What is the volume used for? Financial situation? What type of HDD's do you have available?

Good Luck, wish I could be more help.
 
Upvote 0 Downvote
C

CMV

Honorable
Jan 31, 2014
16
0
10,510
Yes , I need 1x 2x 3x... terms. I don't know how you calculate for each levels (0 to 6 ). Please explain.


 
Upvote 0 Downvote
You must log in or register to reply here.

TRENDING THREADS

Latest posts

Moderators online

Share this page

COMPANY
RESOURCES
FOLLOW
Top Bottom