Tino writes: > Well, we've already got MD4 checksums of file blocks. And if I > understand everything correctly, we DO GET collisions, therefore the > hash chains.
These collisions are because the BackupPC digest is only computed over the first part of the file. > Of course, this if for 256k blocks, IIRC. And "only" 128 bit hashes. > But I don't like the idea of relying on probabilities. I've got enough > uncertainties by flaky hardware, bugs etc. Lessfs uses 192 bit checksums on each file block. The chance of a collision is vanishingly small (and vanishingly smaller than a 128 bit checksum). I don't know if it compares the actual data (as BackupPC does). Perhaps that could be added as an additional option for the paranoid. > I won't trust such a file system for backup data. Most commercial systems use these techniques. Craig ------------------------------------------------------------------------------ OpenSolaris 2009.06 is a cutting edge operating system for enterprises looking to deploy the next generation of Solaris that includes the latest innovations from Sun and the OpenSource community. Download a copy and enjoy capabilities such as Networking, Storage and Virtualization. Go to: http://p.sf.net/sfu/opensolaris-get _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
