CEC - Central Electronic Complex
it generally refers to a discrete portion of the system containing CPU, RAM, etc. the "IO Drawer" would be a separate unit.
backplane is similar to a motherboard, except motherboard has CPU as well, but a backplane does not have a CPU (on IBM servers we have processor cards). Sysplanar is the same as backplane or "motherboard". sys0 is the AIX kernel device of the system planar.
In order to attach devices (like printer...) to an AIX system, we must tell AIX the characteristics of these devices so the OS can send correct signals to the device.
Physical Devices Actual hardware that is connected in some way to the system.
Ports The physical connectors/adapters in the system where physical devices are attached.
Device Drivers Software in the kernel that controls the activity on a port. (format of the data that is sent to the device)
/dev A directory of the logical devices that can be directly accessed by the user.
(Some of the logical devices are only referenced in the ODM and cannot be accessed by users).
Logical Devices Software interfaces (special files) that present a means of accessing a physical device. (to users and programs)
Data transferrred to logical devices will be sent to the appropriate device driver.
Data read from logical devices will be read from the appropriate device driver.
Devices can be one of two types:
- Block device is a structured random access device. Buffering is used to provide a block-at-a-time method of access.
- Character (raw) device is a sequential, stream-oriented device which provides no buffering.
Most block devices also have an equivalent character device. For example, /dev/hd1 provides buffered access to a logical volume whereas /dev/rhd1 provides raw access to the same logical volume.(The raw devices are usually accessed by the kernel.)
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Major and Minor device numbers:
maj.min dev nums
brw------- 1 root system 32,8192 Nov 03 14:19 hdisk3
brw------- 1 root system 32,8194 Nov 03 14:19 hdisk4
brw------- 1 root system 32,8195 Nov 07 07:08 hdisk5
It means: here we have a major device which is 32 and there are minor devices for this major device, which are: 8192,...
More precisely, the major number refers to the software section of code in the kernel which handles that type of device, and the minor number to the particular device of that type.
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cfgmgr - mkdev/rmdev:
The Configuration Manager (cfgmgr) is a program that automatically configures devices on your system during system boot and run time. The Configuration Manager uses the information from the predefined and customized databases during this process, and updates the customized database afterwards.
mkdev either creates an entry in the customized database when configuring a device or moves a device from defined to available. When defined, there is an entry in the customized database already. To move to the available state means the device driver is loaded into the kernel.
rmdev changes device states going in the opposite direction. rmdev without the -d option is used to take a device from the available to the defined state (leaving the entry in the customized database but unloading the device driver). When using the -d option, rmdev removes the device from the customized database.
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LOCATION CODES:
The location code is another way of identifying the physical device. The format is: AB-CD-EF-GH.
Devices with a location code are physical devices. Devices without a location code are logical devices.
physical location code: lscfg | grep hdisk0
AIX location code: lsdev -Cc disk
Both location codes: lsdev -Cc adapter -F "name status physloc location description"
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FRU, VPD:
FRU (Field Replaceable Unit) is the number used by IBM to identify the devices. (sometimes it is called 'Part Number') These are needed forhardware replacement.
VPD (Vital Product Data) is the basic data (infos) about the device which is stored in the EEPROM of the device and it can be read by the OS. It can be presented by the command 'lscfg' and it contains the FRU as well.
lsdev shows information about devices from ODM (-C Customized Devices, -P Predefined Devices
lscfg display vital product data (VPD) such as part numbers, serial numbers...
lsattr display attributes and possible values (the information is obtained from the Configuration database (ODM?), not the device)
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INFO ABOUT THE DEVICES:
prtconf displays system configuration information
lsdev -PH lists supported (predefined) devices (-H shows the header above the column; lsdev -Pc adapter -H)
lsdev -CH lists currently defined and configured devices (lsdev -Cc adapter -H)
lsdev -CHF "name status physloc location description" this will show physical location code and AIX location as well
(Devices with a location code are physical devices. Diveces without a location code are logical devices.)
lsdev -p fscsi0 displays the child devices of the given parent device (in this case the disks of the adapter)
lsdev -l hdisk0 -F parent displays the parent device of the given child device (in this case the adapter of the disk)
(it is the same: lsparent -Cl hdisk0
mkdev -l hdisk1 put from defined into available state (or creates an entry in customized db if there wasn't any)
rmdev -l hdisk1 put from available into defined state
rmdev -dl hdisk1 permanently remove an available or defined device
rendev -l hdisk5 -n hdisk16 it changes the name of the device (as long as it is not in a vg (in AIX 6.1 TL6))
odmget -q parent=pci0 CuDv shows child devices of pci0 (in the output look for the "name" lines)
odmget -q name=pci0 CuDv shows parent of pci0 (in the output look for the "parent" line)
lscfg -v displays characteristics for all devices
lscfg -vl ent1 displays characteristics for the specified device (-l: logical device name)
lscfg -l ent* displays all ent devices (it can be fcs*, fscsi*, scsi*...)
lsattr -El ent1 displays attributes for devices (-l: logical device name, -E:effective attr.)
lsattr -Rl fcs0 -a init_link displays what values can be given to an attribute
odmget PdAt |grep -p reserve_policy displays what values can be given to an attribute
lsslot -c pci lists hot plug pci slots (physical)
lsslot -c slot lists logical slots
lsslot -c phb lists logical slots (PCI Host Bridge)
cfgmgr configures devices and installs device software (no need to use mdev, rmdev)
cfgmgr -v detailed output of cfgmgr
cfgmgr -l fcsX configure detected devices attached to fcsX (it configures child devices as well)
cfgmgr -i /tmp/drivers to install drivers which is in /tmp/drivers automatically during configuration
smitty devices
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Changing state of a device:
1.lsdev -Cc tape in normal case it shows: rmt0 Available ...
2.rmdev -l rmt0 it will show: rmt0 Defined
3.rmdev -dl rmt0 it will show: rmt0 deleted (the device configuration is unloaded from the ODM)
Now rmt0 is completely removed. To redetect the device:
4.cfgmgr after cfgmgr, the lsdev -Cc tape command shows: rmt0 Available ...
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If rmdev does not work because: "... specified device is busy":
1. lsdev -C| grep fcs1 <--check the location (in this case it is 07-00)
2. lsdev -C| grep 07-00 <--check all the devices in this location
3. this will show which process is locking the device
for i in `lsdev -C| grep 07-00 | awk '{print $1}'`; do
fuser /dev/$i
done
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