DESY HOME IT HOME Print Preview Print Window
Last modified: Thu Jun 22 11:34:03 2000

BIOS Settings for DESY Linux Servers
Disclaimer: I wrote up this page after studying the manual carefully. It is next to impossible to test all combinations of BIOS settings. To quote Donald Knuth: "Beware of the above code. I have only proven it correct, not tested it."

The settings listed here are recommended for the ASUS P2B-DS motherboard which is used in some 50 Linux work group servers and farm PCs in the DESY computer center. These servers have

The ASUS P2B-DS BIOS offers this menu: To get your setup quickly, start with 'Load Setup Defaults' and then change or check the points which are not marked as 'Default' below (highlighted in green).

Standard CMOS Setup

You should do pretty well with the BIOS defaults here:
Date and Time
We do not care about the CMOS clock too much since the system clock is synchronised to the DESY time server at boot and kept in sync by the afs daemon. When I explicitely set this clock, I use UTC (GMT) instead of local time.

Hard Disks
The DESY work group server does not have IDE hard disks. Therefore, you may set the TYPE field of all disks to 'none'.

Drive A: 1.44M, 3.5 in (Default)
Standard floppy, used for installation.

Floppy 3 Mode Support : Disabled (Default)
Japanase standard floppy, 1.2 MB on 3.5 in. We don't have it.

Video : EGA/VGA (Default)
For all modern graphics boards.

Halt On : All Errors (Default)
We do not want to run in case of errors. 'All, But Keyboard' may be an option if the missing local keyboard on a server is a problem.

Top of page

BIOS Features Setup

CPU Internal Core Speed : Manual (Default)
Reserved, cannot be changed.

Boot Virus Detection : Enabled (Default)
Some old BIOS versions think that a Linux master boot record is a virus. Must be 'Disabled' in that case.

Processor Serial Number : Disabled (Default)
I see no use in enabling this anti-privacy feature.

CPU Level 1 Cache : Enabled (Default)
Disabling this will kill performance of most applications.

CPU Level 2 Cache : Enabled (Default)
Disabling this will kill performance of most applications.

CPU Level 2 Cache ECC Check : Enabled
Default is 'Disabled, but 'Enabled' should increase data integrity.

BIOS Update : Enabled (Default)
No reason to change the default.

Quick Power On Self Test : Enabled (Default)
Setting it to 'Disabled' will run the power on test four times and delay the boot procedure.

HDD Sequence SCSI/IDE First : SCSI
Default is 'IDE', but DESY server are SCSI only.

Boot Sequence : A,C (Default)
Reasonable inside the Computer Center where physical access is limited. This seuence is needed for installation. On publically accessible systems, this may be changed to 'C only', but this only makes sense if the BIOS is protected with a password

Boot Up Floppy Seek : Disabled (Default)
No reason to change the default as long as the system boots from floppy without it (which it should).

Floppy Disk Access Control : R/W (Default)
Okay inside the computer center, will allow to create boot floppies with this system.

IDE HDD Block Mode Sectors : Disabled
Default is 'HDD MAX', which would speed up I/O on IDE disks if we had any. In theory, it shouldn't make any difference for SCSI

HDD S.M.A.R.T. capability : Disabled (Default)
No reason to change this.

PS/2 Mouse Function Control : Auto (Default)
This reserves IRQ 12 for a PS/2 mouse if one is found at boot. Normally, our servers have neither mouse nor keyboard. Leaving this on 'Auto' won't harm. 'Disabled' is safer (IRQs might otherwise be reassigned if someone connects a mouse during tests with a local console).

OS/2 onboard Memory > 64M : Disabled (Default)
Only useful for OS/2, leave as is.

MPS 1.4 Support : Disabled
Reserved for future use, do not touch.

PCI/VGA Palette Snoop : Disabled (Default)
Useful for a few nonstandard VGA graphics boards, which we don't have.

Video ROM BIOS Shadow : Enabled (Default)
In theory, speeds up the graphics I/O. No need to change it, although it probably won't do much on systems without local monitor.

C8000-CBFFF to DC000-DFFFF : Disabled (Default)
Should be left as is unless you know what you are doing.

Boot Up NumLock Status : On (Default)
No need to change this, though it won't do much on a system without keyboard.

Typematic Rate Setting : Disabled (Default)
We do not have a keyboard - no need to change it.

Typematic Rate (Chars/Sec) : 6 (Default)
We do not have a keyboard - no need to change it.

Typematic Delay (Msec) : 250 (Default)
We do not have a keyboard - no need to change it.

Security Option : Setup
Only useful if you set a password. 'Setup' will only ask for the password if the BIOS setup is called during boot. The default is 'System', which would ask for a password at any reboot. You do not want this on a server!

Top of page

Chipset Features Setup

Most setting in this section can be left on their default. Mind the memory type (ECC vs non-ECC), and it is safe to disable IDE disks.
SDRAM Configuration : By SPD (Default)
Leave this as is. It will configure the memory by the information stored on the DIMM's EEPROM.

SDRAM CAS Latency
Leave on default (Determined by SPD)

SDRAM RAS to CAS Delay
Leave on default (Determined by SPD)

SDRAM RAS Precharge Time
Leave on default (Determined by SPD)

DRAM Idle Timer
Leave on default (Determined by SPD)

SDRAM MA Wait State : Normal (Default)
Leave on default

Snoop Ahead : Enabled (Default)
Leave on default

Host Bus Fast Data Ready : Disabled (Default)
Leave on default

16-bit I/O Recovery Time : 1 BUSCLK (Default)
Leave on default

8-bit I/O Recovery Time : 1 BUSCLK (Default)
Leave on default

Graphics Aperture Size : 64 MB (Default)
Leave on default

Video Memory Cache Module : UC (Default)
Leave on default

PCI 2.1 Support : Enabled (Default)
Leave on default

Memory Hole At 15M - 16M : Disabled (Default)
Leave on default

DRAM are xx bits wide
You cannot enter anything here. If xx=64, you have non-ECC memory. This is bad on server systems because flaky memories may lead to unpredictable and unreproducible errors. ECC memory have xx=72. This is strongly recommended! If you buy cheap, you buy twice!

Data Integrity Mode : ECC
Default is 'Non-ECC', and this can be bad (see above). You will only be able to change this if you have ECC memory. You should!

Onboard FDC Controller : Enabled (Default)
We need the onboard floppy, leave it as is.

Onboard FDC Swap a and B : No Swap (Default)
Leave on default.

Onboard Serial Port 1 : 3F8H/IRQ4 (Default)
Leave on default. We use that for monitoring.

Onboard Serial Port 2 : 2F8H/IRQ3 (Default)
Leave on default. We may use that for monitoring.

Onboard Parallel Port : 378H/IRQ7 (Default)
No need to change it, though it will not be used on servers.

Parallel Port Mode : ECP + EPP (Default)
No need to change it, though it will not be used on servers.

ECP DMA Select : 3 (Default)
No need to change it, though it will not be used on servers.

UART2 Use Infrared : Disabled (Default)
Leave on default.

Onboard PCI IDE Enable : Disable
Default is 'Both', but we don't have IDE disks.

IDE Ultra DMA Mode : Disable
Default is 'Auto', but we don't have IDE disks.

IDE 0 Master PIO/DMA Mode : Auto (Default)
Leave on default.

IDE 1 Slave PIO/DMA Mode : Auto (Default)
Leave on default.

IDE 0 Master/Slave PIO/DMA Mode : Auto (Default)
Leave on default.

IDE 1 Master/Slave PIO/DMA Mode : Auto (Default)
Leave on default.

Top of page

Power Management Setup

We do not want any power management on servers which are supposed to run 24x7. The defaults are not good here.
Power Management : Disable
Default is 'User Define', change it.

Video Off Option : Always On
Default is 'Suspend ->, change it.

Video Off Method : DPMS OFF (Default)
Leave on default.

HDD Power Down : Disable (Default)
Leave on default.

Suspend Mode : Disable (Default)
Leave on default.

PWR Button < 4 Secs : Soft Off (Default)
Leave on default.

PWR Up On Modem Act : Disabled
Default is 'Enabled'. Change it to avoid hassles with the serial console line.

AC PWR Loss Restart : Enabled
Default is 'Disabled'. 'Enabled' will automatically reboot your PC after a power failure.

Power Up By Keyboard : Disabled (Default)
Leave on default.

Wake On Lan : Disabled (Default)
Leave on default.

Automatic Power Up : Disabled (Default)
Leave on default.

Fan Monitor
Display of the fan speeds. Set individual fields to 'Ingore' if necessary.

Thermal Monitor
Display of CPU and motherboard temperatures. Set individual fields to 'Ingore' if necessary.

Voltage Monitor
Display of power supply voltages. Should display reasonable values for all voltages, otherwise your PC will probably not run anyway.

Top of page

PNP and PCI Setup

PNP OS Installed : No (Default)
Leave on default.

Slot 1 IRQ : Auto (Default)
Leave on default.

Slot 2 IRQ : Auto (Default)
Leave on default.

Slot 3 IRQ : Auto (Default)
Leave on default.

Slot 4 IRQ : Auto (Default)
Leave on default.

PCI Latency Timer : 32 PCI Clock (Default)
Leave on default.

IRQ xx Used by ISA : No/ICU (Default)
DESY servers should not have ISA cards. Leave on default.

DMA xx Used by ISA : No/ICU (Default)
DESY servers should not have ISA cards. Leave on default.

ISA MEM Block Base : No/ICU (Default)
DESY servers should not have ISA cards. Leave on default.

Onboard AHA BIOS : Auto (Default)
Leave on default. Sets up the onboard SCSI controller.

ONB AHA BIOS First : No (Default)
Default is okay unless you use additional SCSI controllers and still wnat the onboard controller to have priority.

ONB SCSI SE Term : Enabled (Default)
Normally okay, depending on your SCSI configuration.

ONB SCSI LVD Term : Enabled (Default)
Normally okay, depending on your SCSI configuration.

USB IRQ : Disabled
Default is 'Enabled', but we don't use USB on servers and can save an IRQ here.

VGI BIOS Sequence : PCI/AGP (Default)
Only useful with several graphics boards. Leave on default.

Top of page

Load BIOS Defaults

This will load troubleshooting defaults with minimum functionality. The manual explicitelky states that these settings are non-optimal. Use only when debugging hardware.

Top of page

Load Setup Defaults

If something is completely screwed, use this to load defaults (which should give you a reasoinably running system). In case of problems, change the settings highlighted in the sections above.

Top of page

Supervisor Password

This sets a password for the BIOS settings. may be usefuls on publicly accessible systems, but does not make sense inside the computer center. If you use it, make sure that the password cannot be lost, e.g. by giving it to the computer center.

Top of page

User Password

This password will be asked for on any reboot and is supposed to prevent unauthorised use of the system. Not needed since we run an OS with user authentication. Could be useful on desktops or public systems, but this page is about servers.

Top of page

IDE HDD Auto Detection

Not useful on SCSI only servers. Consult the motherboards manual if you are using IDE disks (discouraged on servers).

Top of page

Save and Exit Setup

This is your way out if you made the changes recommended above. It will save them to CMOS memory.

Top of page

Exit Without Saving

This will discard all changed you made. Use this if you only checked values to make sure that nothing is modified by accident.

Top of page

DESY | DESY -IT- | -IT- Systems Group | DESY Linux
Maintained by the DESY Linux Team
Imprint © 2010 Last update: 31. Jul. 2003 www-it@desy.de