Hello!
I reported the problem some weeks ago - but I did not get an answer. (please
answer to my personal EMail address too).
aic7xxx negotiates a lower SCSI speed the drives are capable of. The affected
systems are the latest stable and developer kernels. ( 2.2.12 / 2.3.19). I
tried 2.2.5 and I got full speed. I am using a PII-233 with an Adaptec 2940U2W
and an old Symbios SCSI controller. My brother has the same problem on his SMP
machine ( 2 x PIII - 450 - SCSI onboard). His Plextor CD-ROM only displays a
SCSI rate of 5 MB/s like all other Fast-SCSI drives. It seems that the SCSI
driver negotiates the speed one step below the maxiumum speed the drive is
capable of.
Here is a part of my boot messages - my system:
(scsi0) <Adaptec AHA-294X Ultra2 SCSI host adapter> found at PCI 10/0
(scsi0) Wide Channel, SCSI ID=7, 32/255 SCBs
(scsi0) Downloading sequencer code... 374 instructions downloaded
ncr53c8xx: at PCI bus 0, device 12, function 0
ncr53c8xx: 53c815 detected
ncr53c815-0: rev=0x04, base=0xe0800000, io_port=0xb800, irq=11
ncr53c815-0: ID 7, Fast-10, Parity Checking
scsi0 : Adaptec AHA274x/284x/294x (EISA/VLB/PCI-Fast SCSI) 5.1.19/3.2.4
<Adaptec AHA-294X Ultra2 SCSI host adapter>
scsi1 : ncr53c8xx - version 3.2a-2
scsi : 2 hosts.
(scsi0:0:3:0) Synchronous at 40.0 Mbyte/sec, offset 15.
Vendor: IBM Model: DDRS-39130D Rev: DC1B
Type: Direct-Access ANSI SCSI revision: 02
Detected scsi disk sda at scsi0, channel 0, id 3, lun 0
Vendor: IBM Model: DCAS-34330 Rev: S65A
Type: Direct-Access ANSI SCSI revision: 02
Detected scsi disk sdb at scsi1, channel 0, id 0, lun 0
Vendor: PLEXTOR Model: CD-ROM PX-32TS Rev: 1.02
Type: CD-ROM ANSI SCSI revision: 02
Vendor: TEAC Model: CD-R55S Rev: 1.0Q
Type: CD-ROM ANSI SCSI revision: 02
scsi : detected 2 SCSI disks total.
SCSI device sda: hdwr sector= 512 bytes. Sectors= 17850000 [8715 MB] [8.7 GB]
ncr53c815-0-<0,*>: FAST-10 SCSI 10.0 MB/s (100 ns, offset 8)
SCSI device sdb: hdwr sector= 512 bytes. Sectors= 8467200 [4134 MB] [4.1 GB]
The IBM DDRS-39130D should do at 80 Mbyte/sec. SCSI bios settings should be Ok.
All other drives are connected to the old SCSI controller at the moment - so I
get 10 MB/s for them.
Greetings
Alexander
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