How To
Summary
How to configure dump device correctly when you use firmware assisted dump type?
Steps
When an unexpected system halt occurs, the system dump facility automatically copies selected areas of kernel data to the primary dump device. Dump files are needed for root cause analysis of system crash issue or system complete hang issue.
To view information about the current dump devices and dump type, enter command:
#sysdumpdev -l
Examples:
There are two dumps devices (a primary and secondary).
If the dump device parameter is:
/dev/hd6: So the paging space LV is being used as a dump device.
/dev/dumplv: It is some other LV name. A dedicated dump device is defined.
/dev/sysdumpnull: No dump device is defined. It is a null device and any dump written to this device is lost and either a paging space or dedicated dump device to be created.
/dev/hd6: So the paging space LV is being used as a dump device.
/dev/dumplv: It is some other LV name. A dedicated dump device is defined.
/dev/sysdumpnull: No dump device is defined. It is a null device and any dump written to this device is lost and either a paging space or dedicated dump device to be created.
Type of dump
Type of dump: fw-assisted: It means the preferred dump type is firmware-assisted system dump.
Type of dump: fw-assisted (suspend): It means the preferred dump type is firmware-assisted system dump, but the primary dump device is either not configured or it does not support firmware-assisted system dump. In the latter case, a traditional system dump is triggered.
Type of dump: traditional: Only the traditional system dump is available after the sysdumpdev -t traditional command. It might also because the firmware-assisted system dump is not supported on this system. To support firmware-assisted system dump, there must be sufficient memory when the system starts up, and POWER6® or later hardware and the supported firmware must be installed.
Consider the following points when you configure dump device by using firmware assisted dump type.
1- If the default paging device hd6 (paging space) is used as the dump device the firmware assisted dump option doesn't work. A traditional system dump is triggered instead.
2- You cannot use firmware-assisted system dumps for the secondary dump device.
- If your system has less than 4 GB of memory, the default dump device is the /dev/hd6 logical volume, which is a paging logical volume.
In addition, if the configuration is for a firmware-assisted system dump you cannot configure the /dev/hd6 logical volume as the dump device. A dedicated logical volume must be configured in to use the firmware assisted dump.
-If a dump occurs to paging space (traditional system dumps only), the system automatically copies the dump when the system is rebooted. By default, the dump is copied to the /var/adm/ras directory in the root volume group.
What is a copy directory? (not applicable if you use a dedicated dump device)
It is a directory in a file system where the dump file is copied when the dump device is set to the paging device hd6.
Forced copy flag (not applicable if you use a dedicated dump device)
This flag is only used if the dump device is set to paging space hd6. If TRUE, a prompt is issued to allow the dump to be copied to external media if for some reason there is a problem when system is copying the dump to the copy directory. If FALSE, no prompt or notice is issued if there is a problem copying the dump to the copy directory, and the dump is lost.
Error message: Failed to copy the dump from /dev/hd6 to /var/adm/ras.
/dev/hd6 is paging space so when system comes up, dump files need to be copied to /var/adm/ras so hd6 could be used as paging space. If for some reason there is a problem when system is copying the dump files to the copy directory, you are asked at boot to copy contents of the hd6 (dump files) to external device.
Don't skip this message and copy the content (dump files) to external media.
IBM support recommends you to use firmware assisted type:
We recommend you to change the dump type on server from traditional to firmware assisted type,
The advantage of firmware assisted dump is that the dump written during system reboot after device discovery while the traditional type is written immediately while server goes down(server crash). If there is a problem accessing the dump device the system dump fails.
Keep in mind fw-assisted type prerequisite for the dump device:
. On rootvg
. Not to be mirrored or stripped
. Not to be the paging space.
. Size = sysdumpdev -e + 10%.
. On rootvg
. Not to be mirrored or stripped
. Not to be the paging space.
. Size = sysdumpdev -e + 10%.
How to enable fw-assisted type?
Use the following commands. Reboot the system so change is applied.
#sysdumpdev -t fw-assisted
# bosboot -ad /dev/ipldevice
#shutdown -Fr
# bosboot -ad /dev/ipldevice
#shutdown -Fr
Related Information
Document Location
Worldwide
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Document Information
Modified date:
08 September 2020
UID
ibm16327193