Use the makedumpfile tool
(version 1.3.7 or higher) can be used to compress s390 dumps and exclude
memory pages that are not needed for analysis. Alternatively, you
can use the gzip and split commands.
About this task
Compressing the dump substantially reduces the size of dump
files and the amount of time needed to transmit them from one location
to another. Because makedumpfile expects as input
dump files in ELF format, you first have to transform your s390 format
dump to ELF format. This is best done by mounting the dump using the zgetdump command.
Procedure
- Mount the dump in ELF format by performing one of these
steps:
- To mount a DASD dump from the partition /dev/dasdb1 to
/mnt, issue:
# zgetdump -m -f elf /dev/dasdb1 /mnt
- To mount a SCSI dump from the partition
/dev/mapper/36005076303ffd40100000000000020c0-part1 to
/mnt, issue:
# zgetdump -m -f elf /dev/mapper/36005076303ffd40100000000000020c0-part1 /mnt
- To mount an NVMe dump from the partition
/dev/nvme0n1p1 to /mnt, issue:
# zgetdump -m -f elf /dev/nvme0n1p1 /mnt
- Create a file with a filtered and compressed version of
the dump.
Use the makedumpfile -d (dump
level) option to excludes pages that are typically not needed to analyze
a kernel problem. For dump level 31, pages containing only zeroes,
pages used to cache file contents (cache, cache private), pages belonging
to user-space processes, and free pages are all excluded.
See
the man page for makedumpfile for a description
of the dump level and other options of makedumpfile.
The following command accesses a dump at
/mnt/dump.elf filters
it with dump level 31, compresses it, and writes it to a file
/dumps/dump.kdump:
# makedumpfile -c -d 31 /mnt/dump.elf /dumps/dump.kdump
You might want to retain a copy of the original dump
file until the problem is resolved. This reserves the option to create
further copies at different dump levels should any of the excluded
pages be required for problem determination.
- Optional: For initial problem analysis, you can also extract the kernel log with
makedumpfile, and send it to your support
organization:
# makedumpfile --dump-dmesg /mnt/dump.elf /dumps/kernel.log
What to do next
After you have used makedumpfile, you
can unmount the dump:# zgetdump -u /mnt