Understanding core files

About core files

When a hardware or software failure causes the filer to crash, the filer creates a core file that Network Appliance Technical Support can use to troubleshoot the problem. The filer stores the core file in the /etc/crash directory on the root volume.

What the savecore command does

The savecore command, which is included in the default /etc/rc file on the root volume, does the following things:

Produces a core.n.nz file. The n in the file name is a number. The string nz indicates that the file is compressed.
Displays a message on the system console.
Logs a message in /etc/messages on the root volume.

Core dump writing

A core dump file contains the contents of memory and NVRAM. Core dumps are written over reserved sections any nonbroken disk owned by the local filer. When a core dump is created, it is stored in uncompressed format if sufficient space is available; otherwise, it is stored in compressed format. If there is insufficient space to store a complete core dump in compressed format, the core dump is canceled.

Note
If the failed filer belongs to a cluster and options cf.takeover.on_panic is enabled, a core dump file is written to a spare disk on that filer.

Core dump files are not compatible between Data ONTAP releases because where the core starts on disks depends on the release. Because of this incompatibility, Data ONTAP might fail to find a core dump file dumped by another release.

Automatic technical support notification

Your filer sends e-mail automatically to Network Appliance Technical Support upon each system reboot if the Autosupport feature is enabled and configured correctly. Network Appliance Technical Support uses the Autosupport message and the core file to troubleshoot the problem.

Manual technical support notification

If you have disabled automatic e-mail, you should contact Network Appliance Technical Support when your system creates a core file.