Support for filesystem snapshots (?)

In the svn book, http://svnbook.red-bean.com/en/1.1/ch05s03.html#svn-ch-5-sect-3.6 on "Repository Backup" describes some backup methods - hot copy, etc. Given that enterprise-level filesystems generally support filesystem snapshots, what is SVN's position on whether such snapshots are sufficient for backups?

Suppose our criteria is that we unplug the network cable between the writer (svn commit) and the filesystem. If unplugging the network cable could yield a repository that is corrupt, then doesn't that mean that there are failure modes where the repository is corrupted? If a filesystem insures that the snapshots behave in this way (as if you disconnect the network cable, make an instant copy, then reconnect), it would seem to imply that these volume-level snapshots would result in a consistent view. If the snapshots are not consistent, then atomicity is not being insured (somewhere between application, client o/s, server o/s, disk controller, media).

My follow up is whether the svn book could include a word about whether it blesses (or not) this form of backup?

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-Justin