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ZGETDUMP(8) System Manager's Manual ZGETDUMP(8)

NAME

zgetdump - Tool for copying and converting System z dumps

SYNOPSIS

zgetdump DUMP [-s SYS] [-f FMT] > DUMP_FILE
-m DUMP [-s SYS] [-f FMT] DIR
-i DUMP [-s SYS]
-d DUMPDEV
-u DIR
-h|-v

DESCRIPTION

The zgetdump tool copies a source dump into a target dump with a configurable dump format. The source dump can be located either on a dump device or on a file system. By default the source dump content is written to standard output, which you can redirect to a specific file. You can also mount the dump content, print dump information, check whether a dump device contains a valid dump tool, or create a non-disruptive dump on a live system.

OPTIONS

Print usage information, then exit.

Print version information, then exit.

Mount the source dump DUMP to mount point DIR and generate a virtual target dump file instead of writing the content to standard output. The virtual dump file gets the name "dump.FMT", where FMT is the name of the specified dump format (see "--fmt" option).

Unmount the dump that is mounted at mount point DIR. This option is a wrapper for "fusermount -u". Instead of DIR also the DUMP (for example /dev/dasdd1) can be specified.

Check the dump disk DUMPDEV for a valid dump tool and print information about it. See chapters DUMPDEV and DUMPDEV INFORMATION below for more information.

Print the dump header information reading from the DUMP and check if the dump is valid. See chapters DUMP and DUMP INFORMATION below for more information.

Show the detailed memory map layout when printing the dump header information (relevant for s390_ext and ELF dump formats).

Use the specified target dump format FMT when writing or mounting the dump. The following target dump formats are supported:

- elf: Executable and Linking Format core dump (default)

- s390: s390 dump

If kdump fails and a stand-alone dump is created, the resulting dump captures two systems: The crashed kdump system and the previously crashed Linux instance. With the "--select" option you can choose which system data to use:

- prod: Data for the initial crashed Linux instance

- kdump: Data for the crashed kdump system

- all: Data for the initial crashed Linux and kdump system

The "-s" option returns an error for dumps that capture only a single crashed system.

DUMP
This parameter specifies the file, partition or tape device node where the source dump is located:
-
Regular dump file (e.g. /dumps/dump.0)
-
DASD partition device node (e.g. /dev/dasdc1)
-
DASD device node for multi-volume dump (e.g. /dev/dasdc)
-
Device mapper multipath partition device node of a FCP attached SCSI disk (e.g. /dev/mapper/3600..20c0-part1)
-
Tape device node (e.g. /dev/ntibm0)
-
Device node for live system (/dev/mem or /dev/crash)
Note: For DASD multi-volume dump it is sufficient to specify only one of the multi-volume DASD partitions as DUMP.

When using the "--device" option, DUMPDEV must be the device node of the dump disk that should be verified. This can be either a DASD device node or a device mapper multipath device node of a FCP attached SCSI disk.

COPY DUMP

The default action of zgetdump is to copy the source dump to standard output in the target format specified by the --fmt option. Read the examples section below for more information.

MOUNT DUMP

Use the "--mount" option to make a source dump accessible to tools that cannot directly read the original dump format. Rather than creating a converted copy of the dump, zgetdump creates a virtual dump file with the requested target format. This is fast and does not consume any additional disk space. Also multi-volume dumps can be assimilated into a single virtual dump file, which can then be accessed directly with dump-processing tools like makedumpfile or crash.

Specify a command of this form to mount and convert a dump:

# zgetdump --mount <DUMP> <DIR> --fmt <FMT>

Where:

is the source dump or dump device
is the mount point where the virtual dump file is created
is the target dump format to which the virtual dump file is converted. The resulting virtual dump file is <DIR>/dump.<FMT>

The virtual dump file exists until the directory is unmounted. Use zgetdump -u <DIR> to unmount a dump.

The zgetdump tool uses the file system in user space (fuse) to mount the source dump. Therefore, the fuse kernel module must to be loaded before using the "--mount" option.

Read the examples section below for more information.

DUMP FORMATS

The default target format of zgetdump is "elf". Use the "--fmt" option to change the target format. The following dump formats are supported for target and source dump:

Executable and Linking Format core dump. This dump format is also used for Linux user space core dumps.
This dump format is System z specific and is used for DASD and tape dumps.
This dump format is System z specific and is used for DASD dumps only.
This dump format is used by the Linux Kernel Crash Dumps (LKCD) project and also on System z for the "vmconvert" dump tool.
On live systems the /dev/mem or /dev/crash device nodes can be used as source dumps for creating live dumps.
Dump formats created by the "makedumpfile" tool. For these formats only the "--info" option can be used.

DUMP INFORMATION

Depending on the dump format, the following dump attributes are available when calling zgetdump with the "--info" option:

Name of the dump format.
Version number of the dump format.
Dump method that has been used to create the dump. Currently the only supported value for this attribute is "live" which indicates that the dump has been created from a live system and therefore is not consistent.
Time when the dump process was started or ended. The dump time information is printed in your local time zone. E.g. "Wed, 03 Feb 2010 10:47:37 +0100" shows the time at your location. The meaning of "+0100" is that your time zone is one hour behind GMT. You can use the "TZ" environment variable or use the "tzselect" tool to change the time zone. For example, if you know that the dump has been created in Hawaii, you can get the correct time information with:

# TZ='Pacific/Honolulu' zgetdump -i DUMP

Identifier of the CPU that ran the dump tool.
The network node hostname of the Linux system.
The kernel release of the Linux system.
The kernel version of the Linux system.
Architecture (s390 or s390x) on which the dump tool was built.
Architecture (s390 or s390x) of the Linux system.
Number of online CPUs.
Number of total CPUs (online and offline).
Memory range that was dumped. This value is the difference between the last dumped and the first dumped memory address.
Memory range that was available on the system. This value is the difference between the last and the first memory address of the system on which the dump was created. The "real memory range" can differ from the "dump memory range" when the SIZE parameter was used when preparing the dump device with the zipl tool (see man zipl).
Actual size of dump file on disk in megabytes. "Dump file size" may differ from the "dump memory range" because of zero memory chunks.
Available memory chunks in the dump. Some dump tools create multiple memory chunks when creating a dump on a system with memory gaps

DUMPDEV INFORMATION

Depending on the dump tool, the following attributes are available when calling zgetdump with the "--device" option:

Name of the dump tool.
Version of the dump tool.
Architecture (s390 or s390x) of the dump tool.
Type of the DASD where the dump tool is installed (ECKD or FBA).
If this attribute is set, the dump tool will dump memory only up to that limit even if there is more memory available.
If this attribute is set to "yes", the multi-volume DASD dump tool will not verify the dump signature on dump partitions. This can be useful, if the dump partition is also used for swap.
For SCSI partition dump, the partition number and the maximum dump size is printed. The partition number corresponds to the output of "parted /dev/sdx print" or "fdisk -l /dev/sdx".

EXAMPLES

The DASD partition /dev/dasdx1 was prepared for dump with:


# zipl -d /dev/dasdx1

An IPL was performed on the corresponding single-volume dump tool and a dump has been created. To copy the dump from the DASD partition to file dump.elf issue:


# zgetdump /dev/dasdx1 > dump.elf

DASD partitions /dev/dasdx1 and /dev/dasdy1 contained in file dev_list.conf were prepared for multi-volume dump with:


# zipl -M dev_list.conf

An IPL was performed on the corresponding multi-volume dump tool and a dump has been created. To copy the dump from the DASD partitions to file dump.elf issue:


# zgetdump /dev/dasdx > dump.elf

The device mapper multipath partition on a SCSI disk /dev/mapper/3600..20c0-part1 was prepared for dump with:


# zipl -d /dev/mapper/3600..20c0-part1

An IPL was performed on the corresponding dump tool and a dump has been created. To copy the dump from the device mapper partition to file dump.elf issue:


# zgetdump /dev/mapper/3600..20c0-part1 > dump.elf

Tape device /dev/ntibm0 was prepared with:


# zipl -d /dev/ntibm0

An IPL was performed on the corresponding tape dump tool and a dump has been created. To copy the dump from the tape to file dump.elf issue:


# zgetdump /dev/ntibm0 > dump.elf

To store an ELF-format dump from a live system in a file called dump.elf issue:


# nice -n -20 zgetdump /dev/mem > dump.elf

You can redirect standard output to tools like ftp or ssh in order to transfer the dump over the network without copying it into the file system first.

Copy DASD dump using ssh:


# zgetdump /dev/dasdd1 | ssh user@host "cat > dump.elf"

Copy and compress DASD dump using ftp and gzip (note that not all ftp clients can do this):


# ftp host
ftp> put |"zgetdump /dev/dasdd1 | gzip" dump.elf.gz

The same effect can also be achieved by using the "--mount" option and run scp or ftp directly on the mounted virtual dump file.

Mount a single-volume DASD dump as virtual ELF dump file, compress it with the makedumpfile tool, and unmount it with zgetdump:


# zgetdump -m /dev/dasdc1 /dumps
# makedumpfile -c -d 31 -x vmlinux.debug \
/dumps/dump.elf dump.kdump
# zgetdump -u /dumps

Mount a multi-volume DASD dump, process it with the "crash" tool, and unmount it with fusermount:


# zgetdump -m /dev/dasdx /dumps
# crash vmlinux /dumps/dump.elf
# fusermount -u /dumps

Print information about a DASD dump on /dev/dasdd1:


# zgetdump -i /dev/dasdd1

Print information about a dump on a device mapper multipath partition device node of a SCSI disk:


# zgetdump -i /dev/mapper/3600..20c0-part1

Print information about a DASD dump tool on /dev/dasdd:


# zgetdump -d /dev/dasdd

Print information about a dump tool on a SCSI multipath device:


# zgetdump -d /dev/mapper/3600..02c0

NOTES

The ELF dump format is not supported by the zgetdump tool under 31 bit.

While it is not recommended for reasons of recovery and redundancy, FCP attached SCSI disks can also be accessed directly without multipathing, for example via the "/dev/disk/by-path/" device nodes.

SEE ALSO

zipl(8),crash(8),makedumpfile(8),dumpconf(8),vmconvert(1),vmur(8) fdisk(8),parted(8)

April 2012 s390-tools