Capture48 wrote:
Which RAID is correct for you is really hard to say. Depends on your tolerance for data loss.
RAID 1= Is Mirroring. Data from one disk is copied to the other in the background. This is the simplest and cheapest fault tolerance you can get. This tolerance level can be achieved by software or hardware. It is slower than RAID 5, and may cause a drag on your system depending on how it is implemented. In case of a failure with RAID 1 you simply break the mirror and you are up on running on the good disk. There may be systems with Hot swappable RAID 1 disks now, frankly I've not used 1 for years.
Raid 5 = Striping with parity. This means your data and parity data is copied across a number of disks, usually a minimum of 3. With this type of fault tolerance you get 2 times your smallest disk in the set for storage. So if you have 3 disks the first 1TB, the second 3TB, and the third 3TB, you get 2TB of storage. This is because all disks have to formatted alike and since you can't format a 1TB to accommodate 3TB of data, all disks are formatted to the smallest disk. Why only 2X the disk, one disk is always used for parity data, so if any one disk fails the system can recover. Consumer level NAS devices like this often have HOT SWAPPING, meaning at any time you can pull out that 1TB disk and put in a 3TB disk and get up to 6TB of storage. The disadvantage of any RAID/NAS system is it leads people into a false believe that they have a great backup solution. Make no mistake a RAID/NAS is NOT a backup solution, it's a storage solution.
There are different RAID levels but these two are by far the most common, and most others are variations on these two.
Which RAID is correct for you is really hard to sa... (
show quote)
Well said, but one small correction - RAID 5 arrays do not have a dedicated single drive for parity information (Raid 3 and RAID 4 use a dedicated parity drive). On RAID 5, the parity information is rotated across all drives such that every drive has both parity and data (with the data block and its associated parity information not located on the same drive).