RAID 1 or RAID 5?

Posted on 2003-12-09
Last Modified: 2012-06-21
Tell me if my concept of RAID is is on track or way off in east boofoo.  What I really want to know is which is faster, RAID 1 or RAID 5?

Configurations ranked by performance, 1 being fastest.

1. RAID 0 (Disk Striping)
2. RAID 5 (Disk Striping with Parity 0+1)
3. RAID 1 (Disk Mirroring)
Configurations ranked by redundancy/most reliable, 1 being most reliable.

1. RAID 1 (Disk Mirroring)
2. RAID 5 (Disk Striping with Parity 0+1)
3. RAID 0 (Disk Striping)
I understand that the number of disks used is also a variable in the speed of the array.  I could use as much input as possible.  I am trying to win an ongoing debate about this.
Question by:JasonCat
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Expert Comment

ID: 9904691
Sounds like you're going to win the debate!
Here's a good article on RAID.
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Accepted Solution

sirbounty earned 25 total points
ID: 9904698
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Expert Comment

ID: 9906149
The fastest conf is RAID 10 /striping +mirroring/, but you must use 4 disks. For RAID5 you must use 3 disks. This conf is slower than RAID 1 /mirror/ in write operations. /Reads are practically the same/. If you use RAID 0 /striping/ and one disk goes bad, you will lose ALL YOUR DATA!
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Assisted Solution

Callandor earned 25 total points
ID: 9906190
LVL 18

Expert Comment

ID: 9907032
The answer is an unqualified "it depends"
All things being equal raid0 will provide the highest performance - until you saturate your bus or HBA.

A fast raid controller on a 33mhz pci pus will probably perform just as well in raid5 as raid0, as you can't get enough data to it to make the parity calculation times meaningful. You have to comapre the pipe pf the array to the bus and subract the overhead to see if the raid level will affect throughput.

RAID1 can often be faster on reads as the data can be read from either drive.

RAID1 isn't anymore fault tolerant than RAID5 although you'll see less of a performance hit in a degraded state than because of the lack of parity calculations. You lose a disk it keeps on ticking. Either can use hot spares to mitigate a disk loss.

Dulplexing is the most fault tolereant, wherein two seperate controllers are used for mirroring ( raid 3/5 arrays can be mirrored as well) has some performance figures.
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Expert Comment

ID: 9907041
BTW: AFAIK east boofoo is just past the boonies... just go a mile past where the old schoolhouse burned down and turn left when you see a sleeping dog
LVL 69

Expert Comment

ID: 9907500
>BTW: AFAIK east boofoo is just past the boonies... just go a mile past where the old schoolhouse burned down and turn left when you see a sleeping dog

Aha!  I was wondering what was the name of that place! ;-)

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