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When using dump to generate level 0 dumps which are then rsync'ed

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to a remote machine, the fact that the dump date is stored with
each header (inode) record makes rsync significantly less efficient
than necessary. This also applies to inode access times when they
are not important data to retain. When implementing an offsite
backup solution of this type, these dates in particular are not
important, especially if it prevents effective offsite backups.

PR:           bin/91049
Submitted by: Forrest W Christian <fwc@mt.net>
This commit is contained in:
Kirk McKusick 2008-05-23 23:13:14 +00:00
parent 25f292128c
commit 693c40a39a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=179267
4 changed files with 51 additions and 4 deletions
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23
sbin/dump/dump.8
View File

@ -38,7 +38,7 @@
.Nd file system backup
.Sh SYNOPSIS
.Nm
.Op Fl 0123456789acLnSu
.Op Fl 0123456789acLnrRSu
.Op Fl B Ar records
.Op Fl b Ar blocksize
.Op Fl C Ar cachesize
@ -258,6 +258,27 @@ notify all operators in the group
.Dq operator
by means similar to a
.Xr wall 1 .
.It Fl r
Be rsync-friendly.
Normally dump stores the date of the current
and prior dump in numerous places throughout the dump.
These scattered changes significantly slow down rsync or
another incremental file transfer program when they are
used to update a remote copy of a level 0 dump,
since the date changes for each dump.
This option sets both dates to the epoch, permitting
rsync to be much more efficient when transferring a dump file.
.It Fl R
Be even more rsync-friendly.
This option disables the storage of the actual inode access time
(storing it instead as the inode's modified time).
This option permits rsync to be even more efficient
when transferring dumps generated from filesystems with numerous files
which are not changing other than their access times.
The
.Fl R
option also sets
.Fl r .
.It Fl S
Display an estimate of the backup size and the number of
tapes required, and exit without actually performing the dump.

1
sbin/dump/dump.h
View File

@ -75,6 +75,7 @@ int etapes; /* estimated number of tapes */
int nonodump; /* if set, do not honor UF_NODUMP user flags */
int unlimited; /* if set, write to end of medium */
int cachesize; /* size of block cache in bytes */
int rsync_friendly; /* be friendly with rsync */
int notify; /* notify operator flag */
int blockswritten; /* number of blocks written on current tape */

26
sbin/dump/main.c
View File

@ -117,13 +117,14 @@ main(int argc, char *argv[])
if (TP_BSIZE / DEV_BSIZE == 0 || TP_BSIZE % DEV_BSIZE != 0)
quit("TP_BSIZE must be a multiple of DEV_BSIZE\n");
level = '0';
rsync_friendly = 0;
if (argc < 2)
usage();
obsolete(&argc, &argv);
while ((ch = getopt(argc, argv,
"0123456789aB:b:C:cD:d:f:h:LnP:Ss:T:uWw")) != -1)
"0123456789aB:b:C:cD:d:f:h:LnP:RrSs:T:uWw")) != -1)
switch (ch) {
/* dump level */
case '0': case '1': case '2': case '3': case '4':
@ -189,6 +190,16 @@ main(int argc, char *argv[])
popenout = optarg;
break;
case 'r': /* store slightly less data to be friendly to rsync */
if (rsync_friendly < 1)
rsync_friendly = 1;
break;
case 'R': /* store even less data to be friendlier to rsync */
if (rsync_friendly < 2)
rsync_friendly = 2;
break;
case 'S': /* exit after estimating # of tapes */
just_estimate = 1;
break;
@ -236,6 +247,11 @@ main(int argc, char *argv[])
(void)fprintf(stderr, "\n");
exit(X_STARTUP);
}
if (rsync_friendly && (level>'0')) {
(void)fprintf(stderr, "%s %s\n", "rsync friendly options",
"can be used only with level 0 dumps.");
exit(X_STARTUP);
}
if (Tflag && uflag) {
(void)fprintf(stderr,
"You cannot use the T and u flags together.\n");
@ -384,7 +400,11 @@ main(int argc, char *argv[])
(void)gethostname(spcl.c_host, NAMELEN);
spcl.c_level = level - '0';
spcl.c_type = TS_TAPE;
if (rsync_friendly) {
/* don't store real dump times */
spcl.c_date = 0;
spcl.c_ddate = 0;
}
if (spcl.c_date == 0) {
tmsg = "the epoch\n";
} else {
@ -393,7 +413,7 @@ main(int argc, char *argv[])
}
msg("Date of this level %c dump: %s", level, tmsg);
if (!Tflag)
if (!Tflag && (!rsync_friendly))
getdumptime(); /* /etc/dumpdates snarfed */
if (spcl.c_ddate == 0) {
tmsg = "the epoch\n";

5
sbin/dump/traverse.c
View File

@ -842,6 +842,11 @@ writeheader(ino_t ino)
{
int32_t sum, cnt, *lp;
if (rsync_friendly >= 2) {
/* don't track changes to access time */
spcl.c_atime = spcl.c_mtime;
spcl.c_atimensec = spcl.c_mtimensec;
}
spcl.c_inumber = ino;
spcl.c_magic = FS_UFS2_MAGIC;
spcl.c_checksum = 0;