[clue-tech] Linux on a Dell PowerEdge 2300?

[Bob Bean]

> > Just decide what RAID level you want.     Likely it's 1 or 5.   
> > Configure that in the RAID BIOS, and your set.
> 
> Okay, here's my noob question for the day:  What's the 
> difference? 

RAID 1 (aka "mirroring" or "shadowing") writes every block of data twice -
once on each of two different drives. Which two drives it writes to is
usually decided by the controller firmware.

RAID 5 (aka "parity RAID") groups selected data blocks from each disk drive
into a "stripe", computes an XOR checksum across all the blocks in the
stripe, and stores that checksum on a drive separate from the drives holding
the data. If you lose any of the disks, the data from the missing disk can
be recovered using the surviving data and the XOR checksum.

RAID 1 offers better performance than RAID 5, but your effective data
capacity is halved (each block is stored twice).

RAID 5 offers better capacity efficiency (usually one block of checksum for
every 4 or more blocks of data, reducing the overhead to less than 25%), but
write performance suffers from the overheads of the checksum calculation and
update.

Bob