>>
>>I'm sorry if I'm not agree with you. AFAIK RAID 5 with 3HD is, 1 as primary, 1 as mirror and the other one as ECC. You cannot spread/stripe harddisk without the use of RAID 5+0. But I never did like you said. Can we stripe the HD with RAID 5 ?
>
>The server at a previous job has 3 hard disks of 4.5 GB each, and the total capacity is 9 GB. If what you said is true, only 1 of the 3 hard disks would be used.
>
>The server supposedly has RAID 5, but I didn't previously investigate the differences between RAID 5 and RAID 5+0.
>
>The definition at http://www.pcwebopedia.com/TERM/R/RAID.html says:
>
>"...Level 5: Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance."
>
>The definition also includes several links; see the definition of RAID 5 at http://www.acnc.com/04_01_05.html.
>
>I see no mention of 5+0 at the mentioned sites.

Well.. I never aware that RAID 5 is stripe at the byte level. But I seriously doubt it can spread evenly between HD (like RAID 0) because this is where you gain a true performance. No redundancy, no fault tolerant, no mirroring, just performance. And that's also why we cannot called RAID 0 as a "real" RAID

AFAIK, yes only one harddisk is used to provide the data to the computer. But we don't have to know about the others. The controller will do it's job, it will switch automatically if one of the disk is damage. But if you don't replace it with another one than you won't get a good fault tolerance. But I maybe wrong about this.

For information about RAID 5+0
http://www.tomshardware.com/storage/20030115/ultra160_raid-05.html
http://www.adaptec.com/worldwide/support/techspecs.html?sess=no&language=English+US&prodkey=ASR-2110S&cat=%2fProduct%2fASR-2110S&fromarea=prod