/etc/grio_config File Format

/etc/grio_config File Format

The /etc/grio_config file describes the configuration of the system I/O devices. The cfg command generates /etc/grio_config, based on an optimal I/O size specified on the command cfg line. cfg scans the hardware in the system, the XLV volumes, and the information in the /etc/grio_disks to create /etc/grio_config. You can also edit /etc/grio_config to tune the performance characteristics to fit a given application. Changes to /etc/grio_config do not take effect until the ggd daemon is restarted (see the section "Restarting the ggd Daemon" in this chapter).

The information in /etc/grio_config is used by the ggd daemon to construct a tree that describes the relationships between the components of the I/O system and their bandwidths. In order to grant a rate guarantee on a disk device, the ggd daemon checks that each component in the I/O path from the system bus to the disk device has sufficient available bandwidth.

There are two basic types of records in /etc/grio_config: component records and relationship records. Each record occupies a single line in the file. Component records describe the I/O attributes for a single component in the I/O subsystem. CPU and memory components are described in the file, as well, but do not currently affect the granting or refusal of a rate guarantee.

The format of component records is:

componentname= parameter=value parameter=value ... (descriptive text)

componentname is a text string that identifies a single piece of hardware present in the system. Some componentnames are:

SYSTEM: The machine itself. There is always one SYSTEM component.
CPUn: A CPU board in slot n. It is attached to SYSTEM.
MEMn: A memory board in slot n. It is attached to SYSTEM.
IOBn: An I/O board with n as its internal location identifier. It is attached to SYSTEM.
IOAnm: An I/O adaptor. It is attached to IOBn at location m.
CTRn: SCSI controller number n. It is attached to an I/O adapter.
DSKnUm: Disk device m attached to SCSI controller n.

parameter can be one of the following:

OPTSZ: The optimal I/O size of the component
NUM: The number of OPTSZ I/O requests supported by the component each second
SLOT: The backplane slot number where the component is located, if applicable (not used on all systems)
VER: The CPU type of system (for example, IP22, IP19, and so on; not used on all systems)
NUMCPUS: The number of CPUs attached to the component (valid only for CPU components; not used on all systems)
MHZ: The MHz value of the CPU (valid only for CPU components; not used on all systems)
CTLRNUM: The SCSI controller number of the component
UNIT: The drive address of the component
RT: Set to 1 if the disk is in a real-time subvolume (remove this parameter for soft guarantees)
RPOS: Determines the disk's position in the striped subvolume

The value is the integer or text string value assigned to the parameter. The string enclosed in parentheses at the end of the line describes the component.

Some examples of component records taken from /etc/grio_config on an Indy system are shown below. Each record is a single line, even if it is shown on multiple lines here.

SYSTEM= OPTSZ=65536 NUM=5000 (IP22)
The componentname SYSTEM refers to the system bus. It supports five thousand 64 KB operations per second.
CPU= OPTSZ=65536 NUM=5000 SLOT= 0 VER=IP22 NUMCPUS=1 MHZ=100
This describes a 100 MHz CPU board in slot 0. It supports five thousand 64 KB operations per second.
CTR0= OPTSZ=65536 NUM=100 CTLRNUM=0 (WD33C93B,D)
This describes SCSI controller 0. It supports one hundred 64 KB operations per second.
DSK0U0= OPTSZ=65536 NUM=23 CTLRNUM=0 UNIT=1 (SGI SEAGATE ST31200N9278)
This describes a SCSI disk attached to SCSI controller 0 at drive address 1. It supports twenty-three 64 KB operations per second.

Relationship records describe the relationships between the components in the I/O system. The format of relationship records is:

component: attached_component1 attached_component2 ...

These records indicate that if a guarantee is requested on attached_component1, the ggd daemon must determine if component also has the necessary bandwidth available. This is performed recursively until the SYSTEM component is reached.

Some examples of relationship records taken from /etc/grio_config on an Indy system are:

SYSTEM: CPU
This describes the CPU board as being attached to the system bus.
CTR0: DSK0U1
This describes the SCSI disk at drive address 1 being attached to SCSI controller 0.