shp (04/06/83)
An article appeared recently about doing system backups under UNIX using dump and/or tar. I shall assume the author was speaking of a 4.xbsd system since he mentioned an 11/750. He talked about several problems, which included: - end of tape recognition There have been published fixes to the mag tape device driver to solve the end of tape problem. Make sure your tape drive is up to the proper ECO rev level, particularly TU77's. There are several hardware revs to TU77's that are somewhat related to the end of tape problem. I've never experienced multiple volume tape problems using dump. On our TU77 we had to use 5 2400' tapes per file system. The TU78 requires 2 2400' tapes. Not once has dump messed up and gone off the end of tape. - restoration of entire directories It's true you cannot use /etc/restor to restore an entire directory like you can with tar, however, it's trivial to get /etc/restor to restore directories. First you use dumpdir to get a list of all the files in the directory to be restored; make a second copy of this list. Edit the first copy so that it contains only file names (dumpdir also lists inodes). Edit the second copy so that it is a shell script containing mv(1) instructions to rename the inodes to their proper file names. /etc/restor x `cat first_copy` .... does the actual restore .... second_copy .... renames the files .... - sam praul ...decvax!ittvax!shp
essick (04/08/83)
#R:ittvax:-67000:uiucdcs:13700027:000:529 uiucdcs!essick Apr 7 08:41:00 1983 Rob Kolstad (parsec!kolstad) has a modified version of /etc/restor which he calls "retrieve". Retrieve allows you to read dump tapes the way you would with a tar; it creates intermediate directories, recursively extracts directories and in general does all the things that you wish /etc/restor did. I'm sure he would be more than willing to send copies of the code to interested persons. Rob can be reached at: USENET: decvax!pur-ee!uiucdcs!parsec!kolstad MaBellNet: (214)-669-3700 -- Ray Essick, University of Illinois
kolstad (04/08/83)
#R:ittvax:-67000:parsec:44200004:000:1433 parsec!kolstad Apr 7 11:08:00 1983 Restoring directory trees is an awful experience whether it is labeled 'trivial' or not. We recently had a disk drive failure and wished to restore two dozen users from /mnt to a file system on our remaining disk. The construction of the restor/mv files was awful (mkdir's have to be included also; our shell accepted only 10000 chars for single commands). I disagree that using the tool called 'restor' is the correct solution. I have modified (a much nicer word than hacked) restor.c to create retrieve.c: it (a) allows a trailing * on file/directory names and (b) creates directories automatically in the context of (a). This allows trivial restores of tree structures (with only a single pass across the multiple tapes). The program is currently distributed to four sites. It has a performance problem during restore since it has to check the inode number from the tape against EVERY possible retrieved inode number -- currently by using a linear search. The program has NOT been thoroughly tested with bizarre conditions. In a week or two, I'll submit it to net.sources and prepare to suffer through the incredible amount of comments about lousy user interface and poor implementation strategy (that are ALREADY a part of restor.c). It is unfortunate but true that the new retrieve.c program uses a large list that can be supported only on virtual unix systems. Rob Kolstad PARSEC Scientific Computer Corp.