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Number : 4690 Date : 2003-05-31 Author : Kan Yabumoto Subject : Re: Incremental Backup using XXcopy Size(KB) : 2
DG wrote: > Earlier someone had suggested a combination of switches, > that would work as a sort of incremental backup -(i.e.) > initially backup the entire 4 GB and > later backup only changes. I misplaced this :-( > > a. Is this possible using xxcopy - if so what are the command(s) ? > Of course. Whenever you are trying to do an "ordinary" thing with files, it is very likely that you will find a feature (or combination) to handle that. You need to learn where to find it --> XXTB #27 (http://www.xxcopy.com/xxcopy27.htm). xxcopy \src\ \dst\ /backup xxcopy \src\ \dst\ /clone Both the /backup and /clone switches are a combination of many switches to facilitate typing and memorization. /CLONE has one additional switch (/ZY) and otherwise the two are the same. Both of them compares the source and the destination directory and copies *ALL* files and directories that are not the same. When a file is present in both the source and the destination and the file size and file length are exactly the same, they are treated as same and will be skipped. Therefore, both of these switches are capable of copying everything from the source to the destination --- the very first time, they behave like a full backup and subsequent times, they perform an incremental back skipping the files that have not changed since the last time. The /CLONE operation by the virtue of the /ZY component, will remove files and directories in the destination that are no longer present in the source. This makes /CLONE quite dangerous if you don't type the source or destination directory name correctly (could delete the whole directory if a wrong directory name is specified). The /BACKUP command is much safer because it does not delete anything (it only overwrites existing files). Over time, /BACKUP will accumulate junk file in the destination. If you were to backup a directory for the first time, the two are the same and therefore, /BACKUP is recommended because it's much safer. > b. Is it possible to do this backup on to READ ONLY > Cds ? if so what additional commands need be added Both the /BACKUP and /CLONE operations will copy the file attributes (including the read-only bit) exactly from the source to destination. So, without any extra switches, the destination file will likely be with the read-only if the source files have the read-only bit set --- this is usually no problem since both /BACKUP and /CLONE will overwrite read-only files in the destination anyway (by the virtue of /R switch in them). You may add /K0 if you want to mask the read-only attribute while the files are transferred (will retain other attributes). Or, use /KN (does not retain any of the source file attributes but assigns a new set of attributes as a newly created ordinary file). There are many variations you can add --- just find what feature you want by reading the doc. Kan Yabumoto
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