use backup methods other than files and tapes. The -P argument is
a normal sh(1) pipeline with either $DUMP_VOLUME or $RESTORE_VOLUME
defined in the environment, respectively.
For example, I can back up my home to three DVD+R[W]s as so:
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/ad0s2e 40028550 10093140 26733126 27% /home
green# dump -0 -L -C16 -B4589840 -P 'growisofs -Z /dev/cd0=/dev/fd/0' /home
in the .snap directory in the root of the filesystem being dumped.
Document that if the .snap directory is missing that it must be
created manually and that it should be owned by user root and
group operator and set to mode 770 before a live dump can be run.
called -r but it takes 512 byte blocks instead of megabytes, and I felt a
megabytes specification would be far more useful so I did not use the same
option character.
This will *greatly* improve dump performance at the cost of possibly
missing filesystem changes that occur between passes, and does a fairly
good job making up for the loss of buffered block devices. Caching is disabled
by default to retain historical behavior.
In tests, dump performance improved by about 40% when dumping / or /usr.
Beware that dump forks and the cache may wind up being larger then you
specify, but a more complex shared memory implementation would not produce
results that are all that much better so I kept it simple for now.
MFC after: 3 days
live filesystem. To obtain a consistent dump image, dump takes
a snapshot of the filesystem and then does a dump of the snapshot.
The snapshot is removed when the dump is complete.
Also add an operator warning that the `L' option should be used
if dump is run on a live filesystem without the `L' option being
specified. The alternative would be to silently use a snapshot
any time that a live filesystem is dumped, but this change in
dump semantics seemed too drastic at this time.
Sponsored by: DARPA & NAI Labs.
Approved by: re
blocksizes, etc
does not give the default of -b
only mentiones rdump in the NAME section
uses both filesystem and file system in similar contexts
PR: 34248
Submitted by: Gary W. Swearingen <swear@blarg.net>
MFC after: 3 days
