How to calculate effective disk capacity with RAID 5?
Hi,
I'm planning to install a storage server for a client, using an HP Proliant Microserver with 4 x 2 TB harddisks and RAID 5. I have a similar configuration in my office, only with much smaller disks. Each disk is 250 GB. Here's what this looks like: Code:
[root@nestor:~] # cat /proc/mdstat Q: is there any formula or rule of thumb to calculate this storage space for disks with a different size, in my case 2 TB each? Cheers, Niki |
Raid 5 should give you the capacity of N_disks - 1. You need to keep in mind though formatted capacity is not the same as partition size. The filesystem itself uses some space.
Also df, ls etc report values in powers of 2, it looks like fdisk in your screen shot is using powers of 10. So what is sold to you as 250GB disk is really more like 238. |
OK thanks. It's just to have a rough idea. So basically my 4 x 2 TB array with RAID 5 will offer 4 x 2 - 2 = 6 TB minus some weird math powers stuff, so let's give it something between 5.0 and 5.5 TB. ;)
Cheers, Niki |
Just use df -H (capital H) to get correct numbers with SI prefixes.
|
All times are GMT -5. The time now is 04:41 AM. |