Calculating available disk space in a RAID-5 set
Learn how to calculate disk space availability for five 36 GB disks using RAID-5.
I'm trying to find out how to calculate how much disk space will be available from five 36 GB disks using RAID-5. Can you help me out?
Five 36 GB drives in a RAID-5 configuration yields 144 GB of useable space. I figured this out using a RAID calculator from ibeast that can be found at http://www.ibeast.com/content/tools/RaidCalc/RaidCalc.asp
In addition to providing the simple RAID calculations, the tool also provides information on the various RAID configurations. For RAID-5, the tool provides:
RAID level 5 data striping with distributed parity definition
----------------------------------------------
Data is striped across a group of disk drives with distributed parity. Parity information is written to a different disk in the array for each stripe.
Redundancy
----------------------------------------------
Parity is distributed across the disks in the array. Data is regenerated in the event of a drive failure.
Performance
----------------------------------------------
High performance in small record, multiprocessing environments because there is no contention for the parity disk and read and write operations can be overlapped. No write bottlenecks as with RAID-4.
Drawbacks
----------------------------------------------
Distributed parity causes overhead on write operations. There is also overhead created when data is changed, because parity information must be located and then recalculated.
