my setup:
IBM x3550 server running RedHat Enterprise 5 kernel 2.6.18-8.1.8.el5xen
2x Infortrend A16U-G2421-1 SCSI to SATA storage units
16x seagate 400GB 7200rpm SATA drives in each unit
Adaptec 39320a-r SCSI card

When i tried separating the arrays into 3 ~1.8TB drives, linux didn't seem to treat these drives as block devices. When i try to do anything with them including mount them i get an error saying that they aren't block devices. All 3 drives were listed as /dev/sda sdb sdc but none of them were usable. After a few days of banging my head against a wall and googling I got fed up and decided that i would like to just make each storage unit one big drive of about 5TB anyways.

From what i can tell RHEL5, the scsi card, and the storage units are all capable of this. So after reconfiguring the storage units to raid 6+ a spare drive i got a single drive of 4.8TB on each unit. However the scsi bios now shows this drive as 0MB. The drive still shows up in /dev as sda, but still isn't accessible. I don't currently have the second unit connected.

I'm looking for suggestions on where to start trying to get this working as i am fairly new to linux.

Here is the output of dmesg | grep scsi
scsi0 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 3.0
scsi0:A:1:0: Tagged Queuing enabled. Depth 4
sd 0:0:1:0: Attached scsi disk sda
scsi1 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 3.0
scsi2 : ahci
scsi3 : ahci
scsi4 : ahci
scsi5 : ahci
scsi6 : ahci
scsi7 : ahci
sd 2:0:0:0: Attached scsi disk sdb
sd 4:0:0:0: Attached scsi disk sdc
sd 0:0:1:0: Attached scsi generic sg0 type 0
sd 2:0:0:0: Attached scsi generic sg1 type 0
sd 4:0:0:0: Attached scsi generic sg2 type 0

and cat /proc/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 01 Lun: 00
Vendor: IFT Model: A16U-G2421-1 Rev: 347B
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: WDC WD1600JS-23M Rev: 03.0
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi4 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: WDC WD1600JS-23M Rev: 03.0
Type: Direct-Access ANSI SCSI revision: 05


I also have a related question for anyone who has used one of these storage units before. I swapped out a drive that was listed as not being there, and the new drive has the same issue. Out of curiosity (and because the unit wasn't setup yet so i didn't see any harm) i swapped the new drive with the drive above it, now they both are listed as not being there. After restarting the units controller i have the same issue. How do i make the thing detect the drives again?

Looks similar to a couple arrays I have..
since you've configured the array, have you created any partitions on it or file systems on those partitions ?
fdisk -l should show the partitions and file systems on all connected drives.

If you go into the management software for the array, (or possibly through a direct console connection to the array) what status does it show on those specific drives that are off-line ? you may need to select those drives and make them available again to the pool for use it the array. Boy that's a really bad explanation, but when you look at the array manager you should see what I'm referring to.

man fdisk
man mkfs
man mkfs.ext3

once partitions and file systems are created they would be mounted as..
/dev/sda1
/dev/sdb1
/dev/sdc1

or are you getting some specific of error when you do fdisk /dev/sda ? if so what is the exact error message ?

I fiddled with the scsi card settings and resolved a resource error. I can now access /dev/sda without an error.

as i understand it fdisk can't handle large partitions, but here is the new output of fdisk -l:
and parted -l:
It is still reporting the size as 2.199TB. But it should be 4.8TB according to the drive tray. Parted let me create a label, and will let me partition it, but without the proper drive size there isn't much point to setting up partitions.

Edit:
It seems the problem is the sector size. with 512 the largest size i can address is 512b * 0xFFFFFFFF = 2.199TB. I'll try to change that and hopefully it will solve my problem.

Looks like you hit the nail on the head for the sector size issue...

http://www.maxtronic.com/ftp/manuals/2tb.pdf