RAID Setup

[ace2109]

Hi guys,
I have been doing some digging around on google to find out more about raid as i have never played around with it before.

Am i right in saying you need 4 disks of any size, and they make basically 4 copies of a single file and then if 1 drive fails the others continue to work? Am i also right it saying that as sson as you replace the faulty drive the other drives fill the new one up with all up to date data?

Can you replace the drive without shutting down the machine?????

If this is the case is there such thing as a case that has the drives mounted in such a way that if one fails its just a matter of pulling the hard drive out of the front on rails like some cases have for dvd drives and replacing it with a new one?

i only ask guys because i recently built a huge server for some guys i know and they are using an awful amount of storage, in fact i put 6 500gb drives into for them. I was just wondering about the best way of doing backups to save time.

 

[BillytheImpaler]

Right off the bat I must make it clear that RAID is not a backup method.

RAID comes in a variety of types. These can be divided into two main classifications, striped and mirrored. Striping spreads the data across at least two disks, putting half on each. It is intended to make disk access faster. If you lost a disk in this array all data would be lost. The RAID level most closely associated with this is RAID 0.

Mirroring writes the same data across at least two disks. Is intended to help prevent data loss in case a disk fails. if you lost a disk in this array no data would be lost; you'd merely have to rebuild the array. The RAID level most closely associated with this is RAID 1.

Beyond these there are nested levels, such as RAID 10 where mirrored arrays are themselves placed in a striped array.

Read the Wikipedia article on RAID for an excellent overview.

Replacing a drive while the machine is on is largely a function of the disk host; whether or not it supports hotplugging.

There are such cases. Search for hot swap enclosures.

EDIT: To be completely honest with you, if your client's data is important it should be left in the hands of someone who is familiar with enterprise-level data security, not a novice. I wouldn't trust myself with that much important data.

For actual backups you should look at tape storage. You'd create two copies of the data tapes. The first copy would be stored on-site in case of a smaller mishap such as a dead drive or array. The other would be stored offsite such as in a bank vault in case something catastrophic happened, such as a fire or flood.

 

[crazyDAJT]

there are many raid levels,

the most popular 3 levels are raid 0,1 and 5

raid 0, make 2 disks one, which gives increased read wright cycles, think of it as writing with both hands, this requires a minimum of 2 disks, if a disk dies you are screwed as all data will be lost

raid 1, makes a two disks which are mirrored, this means if one fails the other will still be there, which is nice, you also get increased read times, but suffer on wrights minimum of 2 drives

raid 5, is kind of a mix of the two, using a minimum of 3 drives, you lose one drive in the array to parity, goggle it as it will take to long to explain

you can hotswop drives, if your controller supports this, most do

you will want two of these for 6 drives you can assess quickly:

http://www.overclockers.co.uk/showproduct.php?prodid=HD-019-BT&groupid=701&catid=14&subcat=72

if your making a server, look at raid five, this may be expensive if you motherbord don't support it,


EDIT: as BillytheImpaler mentioned, RAID is not a method of back up, but it can be used in back up systems