On Fri, Sep 11, 2015 at 09:12:46AM -0400, Robert Heller wrote: > I am using the Amanda 2.5.0p2 client on a MacOSX (matching a Amanda 2.5.0p2 > server on a CentOS 5.11 system) and have it set up to use GnuTAR for backup > on > the Mac (a MacMini). This works OK, but there are some weirdnesses: > > The incremental backups (level > 0) are just about as large as the level 0 > backups. Why is this? Is there something I could/should do special? > Not knowing Macs, my comments are based on UNIX/Linux and the assumption that Macs are similar in ways that count :)
A file's metadata, stored in the file's inode, includes three time stamps: "atime" (data access or read), "mtime" (data modification or write), and "ctime" (metadata change). ctime is modified by access, write, or other metadata changes eg. ownership or permission changes. GnuTAR incrementals are mostly (?entirely?) based on ctime changes. Look for something that scans the contents of all files each day. Maybe content indexer's, anti-virus, or ??? These might change atime and thus ctime. Linux and UNIX have filesystem mount options (eg noatime) that limit atime changes to only when other inode changes are needed. See if your Mac supports similar options and if they are being used. BTW, Linux's "ls(1)" command normally shows mtime with the -l options. You can see the other times by adding the "c" (ctime) or "u" (atime) options, i.e. "ls -lu". If you find a lot of files have the same atime or ctime you know when a command may have scanned everything. Jon -- Jon H. LaBadie [email protected] 11226 South Shore Rd. (703) 787-0688 (H) Reston, VA 20190 (703) 935-6720 (C)
