fsck checking. Applying these changes (typically via mergemaster)
will cause your system to start running background checks on all
your soft update enabled filesystems (provided that you have
a kernel with the required functionality, e.g., one built since
the end of April). Please report any and all problems to
mckusick@mckusick.com (not mckusick@freebsd.org which I read
infrequently). See the comment above the fsck command in /etc/rc
for instructions on how to disable background checking should it
cause you too much trouble.
Several FAQs:
1) Can I reboot before the background checks are done?
Ans) Yes, when the system restarts the checks will pick up
where they left off.
2) Can a crash during checking corrupt my filesystem?
Ans) No, recovered resources are returned to the system using soft
updates which ensure that the freeing is done in a safe order.
3) How will I know if any background checks are being done?
Ans) Filesystems that are to be checked in background will be listed
as `DEFER FOR BACKGROUND CHECKING' at the usual fsck check time
during system startup.
4) What happens to the output of the background checks?
Ans) It is sent to syslog `daemon' facility log level `notice'.
5) When will this feature be available in the 4.X kernel?
Ans) Never. It is much too radical and extensive a change to be
MFC'ed. Besides, it needs many months of experience and
tuning before it is ready for widespread use.
6) What happens if a background fsck fails (i.e., fsck finds
errors that would normally require a manual fsck)?
Ans) The filesystem will be marked as needing a manual fsck.
At the next system reboot, the check will be done in
foreground and the usual actions taken (usually a failure
to go multi-user until fsck has been run by hand on the
affected filesystem).
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