what RAID help

matt_griff · 10 May 2011 at 20:20

Hi, I had a recent drive failure and I lost all my data so I'm now looking to put 4 x Samsung f3 1tb in raid but not sure which raid I need.
The thing is while I'm waiting for Samsung to RMA my drive I have bought 3 and want to set just 3 up for now until Samsung send me the new drive which could take a month or more.
So what I want eventually is 2 drives in raid 0 but backed up by the other 2 drives.

Can I do this with 3 for now and then add the 4th drive when it arrives or will I have to just have 2 drives for now?

Mobo is asus p8p67 pro.

Thanks

JonJ678 · 10 May 2011 at 20:47

You don't want raid, you want a backup.

matt_griff · 10 May 2011 at 21:12

I want 2 x drives in raid0 but backed up.

Surveyor · 10 May 2011 at 21:18

matt_griff said:
I want 2 x drives in raid0 but backed up.

Then 2x1TB drives in RAID 0 and back them up to a separate 2TB drive.

So what I want eventually is 2 drives in raid 0 but backed up by the other 2 drives

This is sort of RAID 10.

2 RAID 0 drives mirrored onto 2 more drives.

I say sort off because it's not really a backup but is intended more for redundancy. If one drive fails you can replace it and rebuild the array. But if the array fails, or you suffer a major failure, you'll still risk losing your data.

matt_griff · 11 May 2011 at 05:02

Yes I think raid 10 is the one I need.
Am I right in thinking that if I set my 4 drives up in raid 10 that If one drive goes down my data is ok but if more than one go down I have lost everything?

If I wanted to increase the size in the future to 6 drives would I need to format everything and restart the raid 10 or can I just add to the current raid setup?

Surveyor · 11 May 2011 at 07:19

matt_griff said:
Am I right in thinking that if I set my 4 drives up in raid 10 that If one drive goes down my data is ok but if more than one go down I have lost everything?

Pretty much. But if, for example, 2 drives went down which were a pair then the other pair should still work (I think).

matt_griff said:
If I wanted to increase the size in the future to 6 drives would I need to format everything and restart the raid 10 or can I just add to the current raid setup?

I think you would have to start again.

I suggest you do a bit of research into RAID 10.

JonJ678 · 11 May 2011 at 12:32

If the controller fails, the motherboard fails, the power supply fails, the array fails to initialise for no good reason and must be rebuilt, your data is gone. If you delete things in error, or you run into data corruption, your data is gone. On the bright side you can add more disks to the array, but there is an error rate associated with it. It's not wise to risk destroying all the data (by adding another disk) without a backup.

Raid is not a backup. Raid 10 is not the same thing as a backed up raid 0. You may well want a raid 0, faster read/write times are always popular. There are arguments for raid 5 in a gigabit nas. Raid 10 in a desktop however, just isn't as good as it sounds.

Instead of raid 10, consider two disks in use, two as backup. Put the OS on one, data on the other as far as possible. Keep an exact (bootable) copy of the OS disk, and a standard copy of the other one. If your OS dies, you can swap in the spare disk. If data is lost, you have the other drive backed up and can similarly plug the spare one in. For the extra hassle in keeping the backups up to date, you get resistance to pretty much everything short of a fire. And there will never be a time when your computer unexpectedly refuses to boot from the array.

dynamis_dk · 11 May 2011 at 15:52

I'm with JonJ678 on this, Working for a big IT group who provide hosting and server support, I now know RAID has its place but it isn't really suitable as a lazy alternitive to a good backup. Backing up data isn't always a hard task. I Simply have a drive the same size as my PC data drive, in a USB enclosure and a application which sync's the data across the drives. Once a week or so I plug the USB drive in, sync and jobs a good one. Then I have a one week period of protection against drive fail or data corruption.

Depending on data importance and update frequancy, you could do it nightly if you needed. Having been on the receiving end of the old 'I'm safe, i'm in RAID' routine myself, I learnt the hard way loosing 2tb of data.. lesson learnt I now backup and for things like family photos i have a offsite backup just in case as I know if they go they are gone forever.

matt_griff · 11 May 2011 at 19:20

Ok I think I understand what your saying.

Raid 10 does backup your data automatically but you have more chance of losing all the data over manually backing up?

dynamis_dk · 11 May 2011 at 19:40

Yea for sure. Problem with raid systems and raid10 included is your creating a realtime backup so say you get a virus or overwrite a bunch of stuff, that will be written to you 'backup' instantly so all copies of the data will take the same damage.

A separate driVe means you have two copies in physically different places rather then 2 sets of the same data in the same array.

That make sense?

philjohn · 11 May 2011 at 21:07

As others have said, RAID is not backup, it's just there to provide redundancy in case of a drive failure (and even then it may not do that as the other drive(s) may go during the rebuild).

Any data I really need is backed up offsite using a service called JungleDisk. Bungs it in an Amazon S3 store (or Rackspace Cloud Files store if you'd rather) for a few $ a month plus any storage fees. Works out at roughly £5-6 a month to make sure all my precious family photos are safe.