Compressed Dump

Compressed Dump White Paper, Version 1.3

page 15

It is possible for dump devices to be used also as paging devices. If savecrash

determines that a dump device is already enabled for paging, and that paging activ-

ity has already taken place on that device, a warning message will indicate that the

dump may be invalid. If a dump device has not already been enabled for paging,

savecrash prevents paging from being enabled to the device by creating the ﬁle /etc/

savecore.LCK. swapon does not enable the device for paging if the device is locked

in /etc/savecore.LCK (see swapon(1M) for more details). As savecrash ﬁnishes sav-

ing the image from each dump device, it updates the /etc/savecore.LCK ﬁle and

optionally executes swapon to enable paging on the device.

Options

-c Mark the dump in the dump device as saved, without performing

any other action. The -c option is useful for manually inhibiting

dump actions called by /sbin/init.d/savecrash.

-f Run savecrash in the foreground only. By default, savecrashruns

in the background when the primary paging device does not con-

tain an unsaved portion of the crash image. Turning this option

on increases system boot-up time, but guarantees that the dump

has been saved when control returns to the caller.

-l Logs the panic information to /etc/shutdownlog as described

above, but does not actually save the dump. The dump is marked

as saved so that future invocations of savecrash do not create

duplicate log entries.

-p Only preserves swap-endangered dump device contents into

crash image ﬁles. Swap-endangered dump devices are those

devices that are also conﬁgured as swap devices by the system.

If all dump devices are conﬁgured as swap devices, the entire

dump will be preserved in the crash directory. If no swap devices

are used as dump devices (dedicated dump devices), only the

INDEX ﬁle and kernel modules will be copied into the crash direc-

tory.

-r Resaves a dump that a previous invocation of savecrash has

marked as already saved. This is useful if the ﬁrst invocation did

ran out of space, and enough space has since been freed to try

again.

-v Enables additional progress messages and diagnostics.

-z savecrash will compress all physical memory image ﬁles and ker-

nel module ﬁles in the dump directory. This option is ignored if the

dump image on the dump device is already compressed. See

crashconf(2). In this case, a warning message will be printed.

-Z savecrash will not compress any ﬁles in the dump directory.If nei-

ther -z nor -Z is speciﬁed and the amount of free disk space is

less than the total dump size, savecrash will compress the image

ﬁles.