Messages in this thread |  | | From | "H. Peter Anvin" <> | Subject | Re: linux-2.4.10-pre5 | Date | 9 Sep 2001 13:18:57 -0700 |
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Followup to: <Pine.LNX.4.33.0109091105380.14479-100000@penguin.transmeta.com> By author: Linus Torvalds <torvalds@transmeta.com> In newsgroup: linux.dev.kernel > > I agree that coherency wrt fsck is something that theoretically would be a > GoodThing(tm). And this is, in fact, why I believe that filesystem > management _must_ have a good interface to the low-level filesystem. > Because you cannot do it any other way. > > This is not a fsck-only issue. I am a total non-believer in the "dump" > program, for example. I always found it to be a totally ridiculous and > idiotic way to make backups. It would be much better to have good > (filesystem-independent) interfaces to do what "dump" wants to do (ie have > ways of explicitly bypassing the accessed bits and get the full inode > information etc). > > Nobody does a "read()" on directories any more to parse the directory > structure. Similarly, nobody should have done a "dump" on the raw device > any more for the last 20 years or so. But some backwards places still do. >
The main reason people seems to still justify use dump/restore is -- believe it or not -- the inability to set atime. One would think this would be a trivial extension to the VFS, even if protected by a capability (CAP_BACKUP?).
The ideal way to run backups I have found is on filesystems which support atomic snapshots -- that way, your backup set becomes not only safe (since it goes through the kernel etc. etc.) but totally coherent, since it is guaranteed to be unchanging. This is a major win for filesystems which can do atomic snapshots, and I'd highly encourage filesystem developers to consider this feature.
-hpa
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