Adaptec AIC-7899 onboard - Slow Transfer

Adaptec AIC-7899 onboard - Slow Transfer

Post by rmarian » Sat, 02 Oct 2004 09:17:01

I am using an Intel SLT2 server mainboard with an onboard dual
AIC-7899 scsi controler. Attached to the end of the scsi controler is
a Quantum SDLT 320 Drive. The problem that i am having is the nigtly
backup will run for 15-16hrs backing up 156GB to tape and Backup Exec
reports that the average tansfer rate is between 130-150mb per minute.
Is this as good as the transfer is going to get with this controller?

The data is being backed up from a Promise 3 disk RAID 5 drive
(external) attached to PCI scsi controler card - either a 2000S Ultra3
Single channel or Adaptec SCSI 29320A card.

Anyone have any suggestions for imrpoving the speed with the onboard
SCSI controller or time to buy another SCSI card?


1. AIC-7899 slow SCSI transfer rate

2. Adaptec AIC-7899 fourth drive problem


I've Intel STL2 motherboard with Adaptec AIC-7899 SCSI controller
integrated. It works for long time without a problem with two SCSI disks:
QUANTUM ATLAS_V_18_WLS 0230 (boot device, SCSI device 0) and
SEAGATE ST336607LW 0007 (SCSI device 1).
The controller is SCSI device 7.

All devices are at the same SCSI cable that has a terminator at the tail
and 5 slots to attach devices. The controller is connected
to the slot that is most distant from terminator. The SCSI device 0
is connected to the slot that is the nearest to terminator
and SCSI device 1 to the slot that is the next.

Now I've got a pair of identical SEAGATE ST373207LW 0003, configured
them as SCSI device 2 and 3. If I attach either one to the slot nearest
to the controller then SCSI BIOS attaches a disk at 40Mbyte/s
and there are lots of read/write errors with it. If I attach disk
to the second slot from the controller, SCSI BIOS attaches disk
at 160Mbyte/s and it works just fine. It does not matter what disk
I use from the pair.

The problem is that I need to attach both disks but one of them
doesn't work (see above) - the one connected to the slot nearest
to the controller.

I've changed SCSI cable - no changes. I've updated motherboard's BIOS
using latest version available from the Intel support site, it did not help.

Pleas help. It it known problem?

Eugene Grosbein

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