Which RAID for CentOS and Which NAS for CentOS?

Question

I am trying to order a DELL server rack mounted PowerEdge R310 Chassis, Up to 4 Hot Plug Hard Drives and LCD.

Question:

1. RAID1 if i use, can i lose a disk and get back data?

   • What happen if i have 2 disk as RAID1, and 1 failed? System keeps running? Can i then simply add a new disk and it continue? Or i need to shutdown the service and start new setup?

2. RAID0 if i use, and disk is damage, can i get back data?

   • performance issue (not important for my case)

3. RAID5 seems more advanced, but expensive, which assure both can be done.

   • best but i just need RAID1 features (safety)

I would like to go with RAID1 or RAID5, do i really need NAS?. Please advise.

Follow up: (based on brilliant advise, i ordered following server)

Basis:
DELL™ PowerEdge™ R310 (4 hot plug hard drives and lcd diagnostics)

Processor:
Intel Xeon X3430, 4C, 2.40Ghz, 8MB Cache, 95W TDP, Turbo, DDR-1333Mhz

Ram:
8GB Memory, DDR3, 1333MHz (2x 4GB Dual ranked UDIMMS)

Raid:
C16 Hot-Swap - RAID1 for SAS 6iR or PERC H200/H700, requires 2 SAS/SATA/SSD HDDs

1st raid: SAS 6iR adapter internal raid controller with cable for hot plug hard drives
250GB, SATA, 3.5-in, 7.2K RPM hard drive (hot plug)

:)

Answer 1

1. Yes. RAID1 is mirrored - everything written to one drive is copied to the other
2. No. 50% of the data will be on the failed drive.
3. That is correct - on a 3-disk (the minimum) RAID5 you only get the space of 2 disks, but is still more efficient on space than RAID1 (2 disks, space of 1)

I would recommend RAID5 over RAID1 if possible as it is more efficient on space.

And I'm puzzled... why do you suddenly throw NAS into the mix? NAS is basically an external hard drive (or cluster of hard drives in a RAID) connected through the network and has nothing to do with the RAID of the server you are ordering.

You can have a NAS if you want one, but you don't need one.