SYSTEMD-PSTORE.SERVICE(8) systemd-pstore.service SYSTEMD-PSTORE.SERVICE(8)
NAME
systemd-pstore.service, systemd-pstore - A service to archive contents
of pstore
SYNOPSIS
/lib/systemd/systemd-pstore
systemd-pstore.service
DESCRIPTION
systemd-pstore.service is a system service that archives the contents
of the Linux persistent storage filesystem, pstore, to other storage,
thus preserving the existing information contained in the pstore, and
clearing pstore storage for future error events.
Linux provides a persistent storage file system, pstore, that can store
error records when the kernel dies (or reboots or powers-off). These
records in turn can be referenced to debug kernel problems (currently
the kernel stores the tail of the kernel log, which also contains a
stack backtrace, into pstore).
The pstore file system supports a variety of backends that map onto
persistent storage, such as the ACPI ERST and UEFI variables. The
pstore backends typically offer a relatively small amount of persistent
storage, e.g. 64KiB, which can quickly fill up and thus prevent
subsequent kernel crashes from recording errors. Thus there is a need
to monitor and extract the pstore contents so that future kernel
problems can also record information in the pstore.
The pstore service is independent of the kdump service. In cloud
environments specifically, host and guest filesystems are on remote
filesystems (e.g. iSCSI or NFS), thus kdump relies (implicitly and/or
explicitly) upon proper operation of networking software *and* hardware
*and* infrastructure. Thus it may not be possible to capture a kernel
coredump to a file since writes over the network may not be possible.
The pstore backend, on the other hand, is completely local and provides
a path to store error records which will survive a reboot and aid in
post-mortem debugging.
The systemd-pstore executable does the actual work. Upon starting, the
pstore.conf file is read and the /sys/fs/pstore/ directory contents are
processed according to the options. Pstore files are written to the
journal, and optionally saved into /var/lib/systemd/pstore/.
CONFIGURATION
The behavior of systemd-pstore is configured through the configuration
file /etc/systemd/pstore.conf and corresponding snippets
/etc/systemd/pstore.conf.d/*.conf, see pstore.conf(5).
Disabling pstore processing
To disable pstore processing by systemd-pstore, set
Storage=none
in pstore.conf(5).
Kernel parameters
The kernel has two parameters,
/sys/module/kernel/parameters/crash_kexec_post_notifiers and
/sys/module/printk/parameters/always_kmsg_dump, that control writes
into pstore. The first enables storing of the kernel log (including
stack trace) into pstore upon a panic or crash, and the second enables
storing of the kernel log upon a normal shutdown (shutdown, reboot,
halt). These parameters can be managed via the tmpfiles.d(5) mechanism,
specifically the file /usr/lib/tmpfiles/systemd-pstore.conf.
USAGE
Data stored in the journal can be viewed with journalctl(1) as usual.
SEE ALSO
pstore.conf(5)
systemd 252 SYSTEMD-PSTORE.SERVICE(8)
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