extended attribute standardization
Jos van den Oever
jvdoever at gmail.com
Mon Nov 27 18:35:06 EET 2006
2006/11/27, Pete Ryland <pdr at pdr.cx>:
> I've been thinking of good uses of xattrs and discussing this
> elsewhere, and we came up with a few good ideas. One is to cache data
> that are otherwise very expensive to generate, like md5sums and rsync
> block checksums. The only drawback is making sure these are kept in
> sync, especially if the md5sum is used as a security measure. This
> would require these xattrs to be automatically removed by the
> filesystem in the case of the file changing, perhaps by being put in a
> separate namespace.
In Strigi, one can calculate the sha1 for each file. This will be
stored in the index and enable quick searching for duplicate files.
When the md5sum / sha1 is stored in an extended attribute, quick
searching is not possible unless the value as indexed in addition.
This takes more diskspace and also adds a second synchronization
problem. In Strigi the synchronization is checked by storing the mtime
of the file along with the filename and the checksum.
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