Slow data transfers to SATA disk drives on RHEL4 u4

[Nadolski, Ed]

Hi,

<Sorry for cross-posting, but this seems relevant to both lists.>

I found the issue below and I seeing the same symptoms on RHEL4 U4 on my
several Optiplex 745 systems. I had to set legacy mode in the BIOS in
order to install at all, and afterwards the data transfer rates to the
SATA disk drives are at a crawl.  

Is this the same PCI issue on the 745's, and will the below ahci fix
work?  Also, what is the correct way to remake initrd? (I've never done
that before.)

Alternately: is there any BIOS upgrade/fix for the PCI ID issue on the
745s and/or 370s that will allow RHEL4 U4 to use ahci on the SATA
drives?

Thanks in advance,
Ed Nadolski


=======================================================
SATA under RHEL4 on a Precision 370?
John_Hull at Dell.com John_Hull at Dell.com
Mon Feb 5 09:42:28 CST 2007

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Two notes:

1) The ide-scsi boot parameter had no affect on the SATA performance.
Presumably that was loaded with RHEL 3 for your CD Burner drive, which
needed SCSI emulation to burn disks

2) There are 2 device drivers for Intel SATA controllers: ata_piix and
ahci. Ata_piix is for "native IDE" mode, and treats the SATA disks as
legacy IDE drives. The AHCI module should provide better overall
performance and the higher transfer speeds you expect.

On the later Precision workstations (380 and 39), switching between SATA
modes in the BIOS caused the SATA controllers to change PCI ID's, which
would tell the OS to load the correct driver. However, on the 370, both
modes have the same PCI ID, so you'll have to switch the driver
manually. Edit your /etc/modprobe.conf file and replace all references
to "ata_piix" with "ahci", remake your initrd(s), and then reboot. You
should then be using the ahci driver.

-----Original Message-----
From: linux-precision-bounces at dell.com
[mailto:linux-precision-bounces at dell.com] On Behalf Of Lawrence
Houston
Sent: Monday, February 05, 2007 9:30 AM
To: linux-precision-Lists
Subject: SATA under RHEL4 on a Precision 370?

Precision Users:

After upgrading a DELL Precision 370 (BIOS has been Flashed to A08 and
the Only DELL Driver being used is for the nVidia Graphics Card) from
its "Original" RHEL3 to RHEL4 I thought it would be interesting to see
if RHEL4's 2.6.9-42.0.8.EL Kernel would support the Internal SATA Drive
Natively with "SATA Operation" set to "RAID/AHCI"???  Although I find
the System still runs at the lesser ATA "UDMA/133" Transfer Rates (as it
was under RHEL3 with "ata-scsi" Emulation being force due to a 2.4.x
Kernel Boot Parameter)!!!:

------------------------------------------------------------------------
--------
SCSI subsystem initialized
libata version 1.20 loaded.
ata_piix 0000:00:1f.2: version 1.05
ata_piix 0000:00:1f.2: MAP [ P0 P2 P1 P3 ]
ACPI: PCI interrupt 0000:00:1f.2[C] -> GSI 20 (level, low) -> IRQ 217
PCI: Setting latency timer of device 0000:00:1f.2 to 64
ata1: SATA max UDMA/133 cmd 0xFE00 ctl 0xFE12 bmdma 0xFEA0 irq 217
ata2: SATA max UDMA/133 cmd 0xFE20 ctl 0xFE32 bmdma 0xFEA8 irq 217
ata1: dev 0 cfg 49:2f00 82:746b 83:7f61 84:4023 85:7469 86:3e41 87:4023
88:207f
ata1: dev 0 ATA-7, max UDMA/133, 312500000 sectors: LBA48
ata1: dev 0 configured for UDMA/133
scsi0 : ata_piix
ata2: SATA port has no device.
scsi1 : ata_piix
   Vendor: ATA       Model: WDC WD1600JS-75N  Rev: 10.0
   Type:   Direct-Access                      ANSI SCSI revision: 05
SCSI device sda: 312500000 512-byte hdwr sectors (160000 MB) SCSI device
sda: drive cache: write back SCSI device sda: 312500000 512-byte hdwr
sectors (160000 MB) SCSI device sda: drive cache: write back
  sda: sda1 sda2 sda3 sda4 < sda5 sda6 > Attached scsi disk sda at
scsi0, channel 0, id 0, lun 0
------------------------------------------------------------------------
--------

I ask since the RHEL3 to RHEL4 Upgrade removed that GRUB Parameter
forcing the "ide-scsi" Emulation!!!  Should the RHEL4 2.6.x Kernels be
able to support the full SATA Transfer Rates and if so how can that be
achieved???

Lawrence Houston  -  (dell at greenfield.dyndns.org)

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