What is RAID?

[Spawn-Inc]

so let me see if i have this right... lets say i go buy 4 hdds 250gbs each. if i took drive 1 and 2 in a raid 0 setup could i raid 1 it with drive 3 and 4 which would also be in raid 0. would that work? and i would end up with 500gbs of space or 1tb?

[OvRiDe]

If you had 4X250GB drives. When it comes to mirroring its a 1 to 1 ratio.. So you could essentially have 2X250GB Volumes, OR if your RAID controller supports RAID 0+1 you could stripe 2 of the 250GB into a 500GB Volume and then mirror that to the other 2 Drives. So you would have 1 500GB Volume using 4 250GB drives. The other option would to use a RAID 5 type setup in which you would stripe all the drives together which would equal 1TB but you must subtract the parity bits, so I believe that would equal about 1/3 of the total capacity. Which would leave you with aprox 750GB's of redundant storage space.

[The Black Pumpkin]

Can you take 5 250's, 4 for the 1TB of raid 5, and the other fifth one for the parity bits?

And if I'm not mistaken, if you stripe two drives of equal value, windows shows one drive, with total capacity including both drives? In other words, 2 100 gb would be a 200 in windows, at double speed? Or did I read your last post wrong...

[danthegeek]

Would a gamer benefit from raid 0? Faster load times, less load lag in Oblivion, etc?

EDIT- also is there a way to setup a raid 0 without loosing the existing data on your Hd?

[OvRiDe]

Can you take 5 250's, 4 for the 1TB of raid 5, and the other fifth one for the parity bits?

And if I'm not mistaken, if you stripe two drives of equal value, windows shows one drive, with total capacity including both drives? In other words, 2 100 gb would be a 200 in windows, at double speed? Or did I read your last post wrong...

Lets just say sorta.. That would be a RAID 0. In a RAID 0 configuration, since there is no parity you get the full sum of the drives capacities. When it comes to speed there are a lot of factors involved. It all depends on how you have your drives configured and the interface that is being used.

This can get really complicated so I will try to keep it as simple as possible. Since I know more about SCSI controllers I will use it as an example.

SCSI Adapters have channels and IDs. A channel is composed of multiple IDs. The Adapter can read/write to multiple channels simultaneously, but it can only read/write to the IDs on that channel one at a time. So if you stripe your data across multiple channels it becomes very fast because all the data can be written or read all at once. But if you drives are all configured on the same channel across multiple IDs, the controller still has to write/read to them one at a time, and therefore some of the speed is lost.

I haven't done a lot of research into how SATA controllers handle data, IE. whether they can read/write to multiple drives simultaneously, but I figure they can.

When it comes to using Windows to stripe the drives, that is called Software RAID and it is RAID 0, or it can also Mirror as well. So you are correct in windows 2 100GB drives would become 1 200GB Volume. In my previous posts I was referring to hardware RAID configurations, which require the controller to perform the striping or mirroring, but the concept is the same for software RAIDs as well. Make sense?

Would a gamer benefit from raid 0? Faster load times, less load lag in Oblivion, etc?

EDIT- also is there a way to setup a raid 0 without loosing the existing data on your Hd?

Yes, with the proper configuration and fast drives, you will see a significant reduction in load times on some games.

as for your second question.. Unfortunately no. In most cases whether its software or hardware RAID, when the RAID array is initialized all data is lost, and you have a bright shiny new Volume ready to be partitioned and formatted.

[Spawn-Inc]

If you had 4X250GB drives. When it comes to mirroring its a 1 to 1 ratio.. So you could essentially have 2X250GB Volumes, OR if your RAID controller supports RAID 0+1 you could stripe 2 of the 250GB into a 500GB Volume and then mirror that to the other 2 Drives. So you would have 1 500GB Volume using 4 250GB drives. The other option would to use a RAID 5 type setup in which you would stripe all the drives together which would equal 1TB but you must subtract the parity bits, so I believe that would equal about 1/3 of the total capacity. Which would leave you with aprox 750GB's of redundant storage space.

so it sounds like it would do what i want. if lets say drive 1 fails then you could replace it with drive 3 right? then you would be left with a regular raid 0 setup + the 1 extra drive?

also +rep for heling with raid stuffs!

[OvRiDe]

Im sorry but I am not sure which scenario you are referring to. But once a drive becomes part of a RAID set there is no going back with the exception of RAID 1 or mirroring. In some cases you can "break" the mirror and you will have 2 drives that are exactly the same. When it comes to a stripe set, if you remove a disk from the set, you are vulnerable to data loss (RAID 3 and 5) or in the case of RAID 0 your sunk. On high end systems you can have "HOT" spares which are basically blank drives that hang out until a drive fails. Once it detects a failure the controller will automatically rebuild the missing data to the hot spare, which gives you an extra layer of protection. The best and only real solution when it comes to loosing a drive is to replace the bad drive as soon as possible.

Hope this answers your question, if not let me know and I will do my best.

[danthegeek]

Thanks OvRiDe +rep. I may have to give this a try. (sorry of I hi-jacked)

EDIT- Said I have to "spread it around" sorry But A personel +REP I can give

[OvRiDe]

Thanks OvRiDe +rep. I may have to give this a try. (sorry of I hi-jacked)

EDIT- Said I have to "spread it around" sorry But A personel +REP I can give

Hijacked? Absolutely not! To me thats what this is all about, asking questions and using our collective knowledge to help improve ourselves. I am just glad I was able to contribute! And as for the rep Thankyou very much .. although its nice to see the recognition , its not why I am here. I am just glad to help out where I can.

EDIT: The personal rep means more to me then any green box !

[nil8]

OvRiDe, you're all over this. Good job. rep+

Want to explain the difference between hard and soft raid?