SCSI, not seeing Striped

[DrJay]

Hey, strange one for me but I'm new to all this anyway. I'm setting up a Raid-0 with two Atlas 10k IV drives, the 36gig ones. I plugged them both into an old ATTO ul2d card and Windows XP sees them both.

I can format them each for their own drive letter, and they work perfectly on their own. However, once I try to do a STRIPED Raid in XP it says striped but has the disk space and performance of a spanned. It makes no dang sense to me. Here's an image to illustrate:

http://img.photobucket.com/albums/v627/DrJay2003/raid.jpg

I'm missing something REAL dumb and I know it, but don't know what it is!! Anyone? please?!

 

[TheMajor]

http://www.informit.com/articles/article.asp?p=332154&seqNum=3&rl=1

 

[Hefemeister]

a raid 0 stripped array will appear to be 1 drive with twice the size of the origionals (36gb + 36gb=72gb) with no redundancy. a raid 1 mirrored array will appear to be 1 drive with the same size as the origionals (36gb + 36gb = 36gb) each drive contains the same information and either one can fail without loosing info. a raid 0 array will indeed look like spanned disk I think you got your terms mixed up.

 

[DrJay]

a raid 0 stripped array will appear to be 1 drive with twice the size of the origionals (36gb + 36gb=72gb) with no redundancy. a raid 1 mirrored array will appear to be 1 drive with the same size as the origionals (36gb + 36gb = 36gb) each drive contains the same information and either one can fail without loosing info. a raid 0 array will indeed look like spanned disk I think you got your terms mixed up.

Hrm...from the link above your post:

"Striped volumes store data in stripes across two or more physical disks. Data in a striped volume is allocated evenly and across (in stripes) the disks of the striped volume. Storing files in this manner increases the write/read speed to and from your disks."

Allocated evenly across the disks. I'm reading that as your mirrored array example.

Some time ago I had two other scsi drives that I was able to make into the Striped array and it indeed doubled the performance of the drives but was the size of the smaller of the two. Now, about a week later, I can't seem to do the same thing with these drives.

oops..saved it twice. Anyway, there's a 4 meg/sec difference between striped and simple.

 

[Hefemeister]

you still got it a bit wrong. look at this. http://en.wikipedia.org/wiki/Redundant_array_of_independent_disks

scroll down and look at the diagrams for raid 0(stripped) and raid 1 (mirrored). a raid 0 array will run faster but is not double the speed. I have 2 raptors i use in raid 0 for os and games and it is fast just not twice as fast as 1.

 

[DrJay]

ahhh you're absolutely right...obviously. Hey I said I was new at all this haha.

So why almost no performance gain at all? The Striped setup is a mere 4meg/sec faster even after repeated tests. The ATTO UL2D card I'm using is awful old but claims 80 meg/sec. Even using two scsi cards I still only see about 57 meg/s. Do I just need better cards? Likely a driver issue? I'd buy a better card if I was sure I could hit 80-90 meg/sec but I don't really think that's it.