Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have expanded a RAID 5 to include 12 - 3 TB drives. I was expecting seeing a total of 33 TB in the RAID but only see 30 TB. I do not have a hot spare. Could 2 drives be reserved for parity? This server is a Dell R510 with a H700 controller. It function is my media server for Backupexec. The OS is on a separate RAID 1. The data RAID started with 7 - 3 TB drives. Over the past 2 months I have been expanding the RAID one drive at a time to a total of 12 drives.

share|improve this question
Are you sure it's RAID 5 and not RAID 6? – joeqwerty May 11 '12 at 21:03

raid 5 in this config should only be seeing 30TB usable space because 1/8 of the space must be used for parity.

you can find a raid calculator also by web search.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.