Can you have four sat hard drives in Raid mode 0

[dababus]

Was wondering if its possible to have 4 sata hard drives in raid 0 mode.

are they all have to be off the same size, and same brand.

or is possible to have two harddrives of the same size and the other two hard drives of a different size.

 

[Algere]

You can have it in a 4 drive RAID but it won't be called RAID 0.

 

[dababus]

what would it be called then.

also, can i have two raptors 36 gig in raid and two 80 gigs in raid, all four drives being sata.

 

[n0cmonkey]

You should be able to do RAID 0+1 and 5. Maybe others, not an expert.

The two raptors could be in a raid and the 80s could be in a raid, but I am 99% positive they could not be in a raid together.

 

[Nebor]

Originally posted by: Algere
You can have it in a 4 drive RAID but it won't be called RAID 0.

I'll call it what I want to call it. I have a DAIR 64 myself.

 

[AristoV300]

I know on my P4C800-E you can have 4 drives in Raid 0. They will be 2 seperate Raids not 4 together. I have heard of people doing 4 drives together but I believe it is via a raid card.

 

[Pariah]

You can RAID 0 as many drives as the controller can handle above 1. No matter how many drives are involved, it's still RAID 0. If the drives can be connected to the controller, they can be RAID'd, however it is highly recommended that the drives be the same size and at least similar in performance characteristics (same RPM's and platter densities). If you RAID 0 different size drives, the total array capacity will only be x times the smallest drive's capacity.

also, can i have two raptors 36 gig in raid and two 80 gigs in raid, all four drives being sata

I can't "unrecommend" this enough. Not only will you lose 88GB of useable disc space, but the Raptors performance will be dropped to the speed of the other 2 drives meaning the array will likely be slower than the Raptors running by themselves. RAID is not all it is cracked up to be, and very few home users will see any real benefits from using it.

 

[Lonyo]

If you want to do anything, RAID-0 the 2 raptors, use one 80GB for backup of the RAID (since you can't mirror it I don't think).
Then have the other 80GB as spare space.

It's always worth having a backup anwyay.

 

[0roo0roo]

i think he means he wants two sets of raid 0. two mirrored drives for data protection.. no?

 

[LuNoTiCK]

It isn't worth doing unless you had four of the same drives. I also say if you did that you should do raid 5 instead.

 

[Pariah]

Originally posted by: 0roo0roo
i think he means he wants two sets of raid 0. two mirrored drives for data protection.. no?

The same slowest drive holds up the group applies to RAID 0+1. The data is mirrored in real time, so if the mirror drives are slower than the mirrored drives, the mirrored drives have to sit around and wait for the mirror drives to finish writing.

 

[Matthias99]

Originally posted by: Pariah

Originally posted by: 0roo0roo
i think he means he wants two sets of raid 0. two mirrored drives for data protection.. no?

The same slowest drive holds up the group applies to RAID 0+1. The data is mirrored in real time, so if the mirror drives are slower than the mirrored drives, the mirrored drives have to sit around and wait for the mirror drives to finish writing.

However, you could use a RAID 1+0 to get around this (if your controller supports it).

You'd still see a performance degradation, but only on half the stripes (as opposed to all of them). I still don't think it's a good idea.

That is:

 

[Pariah]

No it won't. RAID 10, despite the reverse configuration, still has to have all drives in the array working in synchronized movements meaning slowest holds up the show. Since the 2 mirrors, are in RAID 0, that's where the weakest link takes effect.

 

[Matthias99]

Originally posted by: Pariah
No it won't. RAID 10, despite the reverse configuration, still has to have all drives in the array working in synchronized movements meaning slowest holds up the show. Since the 2 mirrors, are in RAID 0, that's where the weakest link takes effect.

Yes, it does.

Since it's a RAID0 on the 'outside', the data is *striped* across the two RAID1s, not mirrored -- and thus they don't have to run in sync. The Raptors don't have to wait for writes on the slower drives to finish. However, the OS will obviously see lower performance on the disk blocks that are assigned to the slower drives.

With a RAID0+1, every block has to be written to both a Raptor and a slow disk. With a RAID1+0, every block is written to either both Raptors, or both slow disks.

 

[Pariah]

In both RAID 10 and 0+1 all the drives in the array are synced, not acting on their own.

RAID Level 10

"All drives must move in parallel to proper track lowering sustained performance"

After a bit more searching I dug up an Intel page that had a 5 drive RAID 10 array. So, now I don't what to think. It was always my understanding that RAID 10 needed an even number of drives.

Regardless, beyond 3Ware and maybe a couple Promise controllers, no ATA RAID controllers support RAID 10, so it doesn't matter either way.

 

[Matthias99]

Originally posted by: Pariah
In both RAID 10 and 0+1 all the drives in the array are synced, not acting on their own.

RAID Level 10

"All drives must move in parallel to proper track lowering sustained performance"

I think they mean "Within each RAID1, each drive must move in parallel to [the] proper track, lowering sustained performance." If they mean the whole array has to seek in sync, well, they're wrong (although their product may work this way, which would be dumb). I don't know what more to say. Think about it. You have stripes arranged something like this:

Disk1: 0 - 2 - 4 - 6
Disk2: 0 - 2 - 4 - 6

Disk3: 1 - 3 - 5 - 7
Disk4: 1 - 3 - 5 - 7

Operations on stripes 1, 3, 5, and 7 are completely independent from those on 0, 2, 4, and 6. If you read from or write to stripe 0, there's no reason for Disks 3 or 4 to be involved at all, or that you should have 'sync up' with them before you can do your operation. Now, if you do an operation spanning two stripes, yes, you have to wait for the slow disks to finish their part of the job. But there's no reason you should have to wait for operations if they fit into a single stripe.

After a bit more searching I dug up an Intel page that had a 5 drive RAID 10 array. So, now I don't what to think. It was always my understanding that RAID 10 needed an even number of drives.

Not really; each RAID1 can have a different number of mirrors if you feel like it. Normally you'd have the same number of drives on each, though.

Regardless, beyond 3Ware and maybe a couple Promise controllers, no ATA RAID controllers support RAID 10, so it doesn't matter either way.

It's definitely more of an enterprise feature, something you find more often on high-end SCSI RAID cards. It's also less popular now that RAID5 is more widespread; you get better space utilization, most of the performance (writes are a little slower in RAID5), and can still tolerate a single drive failure (RAID1+0 can sometimes tolerate 2).

 

[dababus]

Ok, am using the raptors 2 x 36 gigs in raid 0 mode.

my controller card is promise fasttrack tx150 plus.

am only getting 48 mb/s in sandra disk benchmark.

why its so low.

any idea.

 

[Tostada]

The nForce 3 250Gb chipset and the Intel ICH5R chip both have integrated 4-device SATA controllers that support RAID 0, 1 and 0+1. I can't find anything that says if they support 4-way RAID 0, though.

The Promise FastTrak S150 TX4 and SX4 definitely do, but the SX4 is the only thing that lets you do RAID 10 and 5:
"RAID 0 -- Data striped across 2-4 drives for increased performance but no data protection"

http://www.promise.com/product/product_detail_eng.asp?productId=112&familyId=2

And from the FastTrak S150 TX4 User Manual:
"Fast Trak S150 TX4 enables you to create striped arrays with 1, 2, 3, or 4 drives."