o None (well, that we know of, anyways!)

o Large Files:

  UPDATE: Afio 2.4.7-9beta4.1 seems to resolve all known problems
  with large files.

  For older version of afio, the following info may be of interest:

  /------
  | While not a bug in dobackup, the default archiver, afio, does have
  | problems writing files greater than 2GiB. It is suggested that if you
  | have a need to make very large backups, you split the output files.
  |
  | In /etc/dobackup.conf, replace:
  | "BackupProg=/usr/bin/afio -o -T 10k -Z -x"
  | with:
  | "BackupProg=/usr/bin/afio -o -T 10k -Z -x - | split -b 2g >"
  |
  | This will generate normal backup files split on every 2GiB boundary. See
  | the split(1) manpage for more details. The resultant files cannot be
  | restored individually, you will need to concatenate them together first.
  |
  | From the AFIO docs:
  |
  |     "Looked into the case of reading/writing archives to/from regular
  |     filesystem files which are bigger than 2 GB.  Seem to work on newer
  |     linux systems supporting such large files.  On the recent linux
  |     system I tried (Red Hat 6.2, kernel 2.4.2, GCC 2.95.3, libc.so.6 ->
  |     libc-2.1.3.so) a freshly compiled afio can read and write >2GB
  |     archive files to the filesystem.  HOWEVER I also got reports from
  |     others with _the same_ or _newer_ versions of stuff that their
  |     compiled afio is not able to do this.  I have not found a pattern to
  |     this: your best bet is to recompile the afio executable on your
  |     platform and try."
  |     
  | AFIO's internal format (much like cpio) cannot properly handle archived
  | files (files in the backup set, not the resultant afio archive) larger
  | than 2GiB. Previously, the file would be fully archived, but the wrong
  | information stored in the header, making for a formidable challenge to
  | restore any such file. AFIO 2.4.7 will now refuse to archive any file
  | that is >= 2GiB.
  | 
  | From the AFIO docs:
  | 
  |     "No matter how it is compiled under Linux, afio will now issue a
  |     warning when encountering a >=2GB file in the set to archive, and
  |     not archive that file. The warning will cause nonzero exit (unless
  |     -1 option changes this)."
  \------
