savecore(8) [netbsd man page]
SAVECORE(8) BSD System Manager's Manual SAVECORE(8) NAME
savecore -- save a core dump of the operating system SYNOPSIS
savecore [-fvz] [-N system] [-Z level] [directory] savecore -c [-v] [-N system] savecore -n [-v] [-N system] DESCRIPTION
When the NetBSD kernel encounters a fatal error, the panic(9) routine arranges for a snapshot of the contents of physical memory to be writ- ten into a dump area, typically in the swap partition. Upon a subsequent reboot, savecore is typically run out of rc(8), before swapping is enabled, to copy the kernel and the saved memory image into directory, and enters a reboot message and information about the core dump into the system log. If a directory is not specified, then /var/crash is used. The kernel and core file can then be analyzed using various tools, including crash(8), dmesg(8), fstat(1), gdb(1), iostat(8), netstat(1), ps(1), and pstat(8), to attempt to deduce the cause of the crash. Crashes are usually the result of hardware faults or kernel bugs. If a kernel bug is suspected, a full bug report should be filed at http://www.netbsd.org/, or using send-pr(1), containing as much information as possible about the circumstances of the crash. Since crash dumps are typically very large and may contain whatever (potentially confidential) information was in memory at the time of the crash, do NOT include a copy of the crash dump file in the bug report; instead, save it somewhere in the event that a NetBSD developer wants to examine it. The options are as follows: -c Only clears the dump without saving it, so that future invocations of savecore will ignore it. -f Forces a dump to be taken even if the dump doesn't appear correct or there is insufficient disk space. -n Check whether a dump is present without taking further action. The command exits with zero status if a dump is present, or with non-zero status otherwise. -N Use system as the kernel instead of the default (returned by getbootfile(3)). Note that getbootfile(3) uses secure_path(3) to check that kernel file is ``secure'' and will default to /netbsd if the check fails. -v Prints out some additional debugging information. -z Compresses the core dump and kernel (see gzip(1)). -Z level Set the compression level for -z to level. Defaults to 1 (the fastest compression mode). Refer to gzip(1) for more information regarding the compression level. savecore checks the core dump in various ways to make sure that it is current and that it corresponds to the currently running system. If it passes these checks, it saves the core image in directory/netbsd.#.core and the system in directory/netbsd.# (or in directory/netbsd.#.core.gz and directory/netbsd.#.gz, respectively, if the -z option is used). The ``#'' is the number from the first line of the file directory/bounds, and it is incremented and stored back into the file each time savecore successfully runs. savecore also checks the available disk space before attempting to make the copies. If there is insufficient disk space in the file system containing directory, or if the file directory/minfree exists and the number of free kilobytes (for non-superusers) in the file system after the copies were made would be less than the number in the first line of this file, the copies are not attempted. If savecore successfully copies the kernel and the core dump, the core dump is cleared so that future invocations of savecore will ignore it. SEE ALSO
fstat(1), gdb(1), gzip(1), netstat(1), ps(1), send-pr(1), crash(8), dmesg(8), iostat(8), pstat(8), rc(8), syslogd(8), panic(9) HISTORY
The savecore command appeared in 4.1BSD. BUGS
The minfree code does not consider the effect of compression. BSD
September 13, 2011 BSD
Check Out this Related Man Page
savecore(1M) System Administration Commands savecore(1M) NAME
savecore - save a crash dump of the operating system SYNOPSIS
/usr/bin/savecore [-Lvd] [-f dumpfile] [directory] DESCRIPTION
The savecore utility saves a crash dump of the kernel (assuming that one was made) and writes a reboot message in the shutdown log. It is invoked by the dumpadm service each time the system boots. savecore saves the crash dump data in the file directory/vmcore.n and the kernel's namelist in directory/unix.n. The trailing .n in the pathnames is replaced by a number which grows every time savecore is run in that directory. Before writing out a crash dump, savecore reads a number from the file directory/minfree. This is the minimum number of kilobytes that must remain free on the file system containing directory. If after saving the crash dump the file system containing directory would have less free space the number of kilobytes specified in minfree, the crash dump is not saved. if the minfree file does not exist, savecore assumes a minfree value of 1 megabyte. The savecore utility also logs a reboot message using facility LOG_AUTH (see syslog(3C)). If the system crashed as a result of a panic, savecore logs the panic string too. OPTIONS
The following options are supported: -d Disregard dump header valid flag. Force savecore to attempt to save a crash dump even if the header information stored on the dump device indicates the dump has already been saved. -f dumpfile Attempt to save a crash dump from the specified file instead of from the system's current dump device. This option may be useful if the information stored on the dump device has been copied to an on-disk file by means of the dd(1M) command. -L Save a crash dump of the live running Solaris system, without actually rebooting or altering the system in any way. This option forces savecore to save a live snapshot of the system to the dump device, and then immediately to retrieve the data and to write it out to a new set of crash dump files in the specified directory. Live system crash dumps can only be per- formed if you have configured your system to have a dedicated dump device using dumpadm(1M). savecore -L does not suspend the system, so the contents of memory continue to change while the dump is saved. This means that live crash dumps are not fully self-consistent. -v Verbose. Enables verbose error messages from savecore. OPERANDS
The following operands are supported: directory Save the crash dump files to the specified directory. If directory is not specified, savecore saves the crash dump files to the default savecore directory, configured by dumpadm(1M). FILES
directory/vmcore.n directory/unix.n directory/bounds directory/minfree /var/crash/'uname -n' default crash dump directory ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
adb(1), mdb(1), svcs(1), dd(1M), dumpadm(1M), svcadm(1M), syslog(3C), attributes(5), smf(5) NOTES
The system crash dump service is managed by the service management facility, smf(5), under the service identifier: svc:/system/dumpadm:default Administrative actions on this service, such as enabling, disabling, or requesting restart, can be performed using svcadm(1M). The ser- vice's status can be queried using the svcs(1) command. If the dump device is also being used as a swap device, you must run savecore very soon after booting, before the swap space containing the crash dump is overwritten by programs currently running. SunOS 5.11 25 Sep 2004 savecore(1M)