BeerCheeze
Rated XXX
|
 Posted: Wed, 10 Mar 2004 23:10:54 Post Subject: |
 |
|
No, 5 is never faster than 1 or 0. Doesn't matter the controller or the drives. If you compare apples to apples, you will always lose speed with RAID 5. RAID 5 is used to allow large storage with no down time. It is not designed for speed.
Think about it...
RAID 0 - The controller simply splits the data into multiple drives. Little to no intelligence involved.
RAID 1 - The controller simply writes the same data twice. Again, little to no intelligence involved.
RAID 5 - The controller has to write the data across multiple drives, keeping track of what it has written Do the math on it and the write another bit on the other drive to make the parity either even or odd, depending on the setup.
Here is how RAID 5 works. Let's say you have 5 drives, and one is the parity drive, so you are writing across 4 drives. Let's say it's using even parity. So when you do a write on the drive let's just say it write:
Drive 1: 0
Drive 2: 0
Drive 3: 1
Drive 4: 1
It now has to do the math, 0+0+1+1 = 2 or EVEN so on drive 5 it would write a 0.
Now reading from RAID 5 isn't too bad, but again lot's of overhead having to reassemble all that. However when you lose a drive... it is a LOT slower. Because it has to read everything into it's buffer, do the math and add the missing bit. But... you're still up and operational even after a HDD failure.
Last edited by BeerCheeze on Thu, 11 Mar 2004 00:33:27; edited 1 time in total |
|
