in a RAID5 if I need 300GB total capacity, do all the drives total that amount? 4x80?

Question

Or do they all need to be 4x300? Thanks.

I know that RAID5 requires a minimum of 3 drives, so I will need 3 drives and 1 hot spare..

Answer 1

Using 3 drives they will each need to be 150GB.

Total capacity will equal the sum of all drives minus one.
Therefore using 4 drives this formula will tell you what you need:

4x - x = 300
3x = 300
x = 100

They need to be 4 x 100GB in order for you to have a total of 300GB usable space.



Use this tool to calculate other configurations :
http://www.ibeast.com/content/tools/RaidCalc/RaidCalc.asp

regards,
Philip T

Answer 2

There are a few things to know there:

1. Well the disk size matters depending on how big the smallest disk is, which means for example: If you use 5 disk of different sizes and the smallest one 100 MB and all the other are bigger (100MB +) than that, the raid will set all 5 disks at 100 MB each.

So, effectively it's better to use all the same size not to waste disk space :- )

2. If you need 300 GB total capacity with Raid5, than you have to isolate a few variables: How many disk are there?
Example: 5 disks of 80 GB = 400 GB - 80GB for the parity = +- 320 GB.

There are a few things I did not take in consideration:
- Is it a hardware raid or software raid
- The formatting of the disk will depend on your OS as well
- and others

Answer 3

If you want to use the minimum number of drives for RAID 5, plus an extra one as a hot spare, then buy 4 150MB drives.

Answer 4

no...two drives together total that amount...you need 4 x 150