Performance for raid
 

What would be a better idea? I've got two drives in raid 1 right now. I'd like to add a third drive, so I can have a performance boost. Would 2x drives in raid 0 and a third one not in raid for cron backups of /home copied to the the third drive or all 3 drives in raid 5? Also has anyone seen a good chart showing performance comparisons of the different raid types for example, a chart showing the performance speed of raid 0, 5, and 10 for easy comparison?

im not sure off the top of my head the speads but rule of thumb is

raid 0 is FAST
raid 1 is slower
raid 5 is ok


if you want the system up 24/7 then you need either RAID1 with a hot spare
or RAID 5
I like 5 b/c you get more space out of it.


http://en.wikipedia.org/wiki/RAID

To gain performance and/or additional redundancy the Standard RAID levels can be combined to create hybrid or Nested RAID levels.

RAID 1+0 or 10 = Performance + fault tolerance.
Min 4 HD's needed.


Dell animation, Learning about RAID



http://en.wikipedia.org/wiki/Standard_RAID_levels

http://en.wikipedia.org/wiki/Nested_RAID_levels

Thanks for the replies, but those don't give me speed measurements.

You will probably want to search on google for benchmarks. For raid 5, you may have a performance boost for reads, but writes will be slower.
Whether you use a raid controller or software raid would also be a factor. Most controllers are fake raid and will involve the cpu to calculate the parity. 3ware and maybe adaptec raid controllers are true raid controllers. NAS servers might have a raid cache card installed as will with battery backup.

Be warned that going for the fastest drives, the constant acceleration of the heads consume a lot of power. One person posting on this site had a dual opteron desktop with a raid 5 subsystem populated with rapter drives. He doesn't need to turn up the thermostat for his apartment in the winter, and doesn't run it in the summer because his cooling bill would be too large if he did.

if you read the performance sections it tells you which ones perform better for certain tasks..

Hard to give you graphs etc, when there are so many variables to configuring RAID.
the number of drives used,
The type of controller
etc..
etc..

RAID 0 - Fast Speed - all drive space used - NO FAULT TOLERANCE

RAID 1 - Fault Tolerant - You loose 50% of Drive Space - No performance Gains

RAID 5 - Fault Tolerance - Slow write speed - You loose the equivalent capacity of One drive

RAID 10 - SPEED and Fault Tolerance - loose 50% Drive space - Out performs RAID 5

If you read the pages the information is there

You might want to look at the series of 'build a fast nas' articles over at smallnetworkbuilder.

e.g., and related articles
http://www.smallnetbuilder.com/content/view/27840/77/

I'm afraid that the bad news is that, at least in 'commodity' hardware, on this testing, above a certain level, the speed of the raid levels shows little sign of conforming to what you might think; my suspicion is that limited pci bandwidth is a serious factor here, but maybe that will be confirmed if the series progresses further.