Hi, this thread was originally named "mkisofs aborts but exit value is 0" but went into the fundamental question wether a backup will allow a sufficient restore. Sufficient for the needs of the person or organisation which created the backup. So that they can go on with their operations as if there was neither a restore nor a disaster before the restore. Only the system history between backup and disaster recovery may be lost.
I acknowledge Joerg's effort to make this as safe as possible by help of his program star. I consider to learn about LVM in order to get filesystem snapshots. Nevertheless i do not share his optimism about the universal usability of a properly recorded snapshot backup. >> I wrote: >> Does a snapshot really decrease the probability >> of backing up a file while it is in an ill state ? >> "Ill" in the sense that it does not comply to a >> valid persistent state as expected by its applications >> when they open it. >> Not "ill" in the sense of "a case for fsck". > Joerg Schilling wrote: > If you have an ill designed application, you are lost. > decent applications should write files in a way that > does not create ill states. Shall i really make assumptions about the quality of particular applications while i consider potential backup problems ? Meanwhile i have the idea that shapshots decrease the probability for unusable file copies in the same way as quickly crossing a street reduces the chance to collide with a car. Slow people get overrun more often. But you can also run blindy into a standing car. This, of course, only if there are any cars on the street. If we put all cars into their garages, then there will be no accident. Regardless of speed. Runlevel 0. Another approach would be to learn how to detect cars and to wait until the situation is safe. (But if all cars stand still, a hampering car would never drive away and thus block the crossing forever.) >> A snapshot does not keep you safe if you don't know >> exactly what particular services need to be shutdown >> temporarily. > > When using snapshots, you don't need to shutdown services > while running a backup. I still do not see how a snapshot does prevent to snap intermediate file states which do not suit a service when it opens the file. After restoring a backup such a service or application would make problems. Trying to imagine how i would have to redesign the applications on which i worked in the past ... ... so that all file changes happen atomically ... ... i encounter severe obstacles. Are there guidelines on how to achieve this quality within general purpose programs ? A sysadmin would need a way to determine wether his system components comply. Is there some directory where to learn about snapshot safe software ? (I would like to learn their tricks.) Have a nice day :) Thomas -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
