TiVo Forum Special Member
Registered: Jul 2002
Location: Cambridgeshire, UK
If you want to suggest improvements to the Hinsdale guides, I'm sure hinsdale would be very happy to get a PM from you. I think you over estimate the scope that he's aiming for, though - the document is already intimidatingly large, so I think careful consideration is required before adding more special cases.
Anyway, as I said, making a backup with recordings results in a file the same size as your drive set (~200Gb in your case). I would think most people have more space in their TiVo than their PC's, so the question of practicality doesn't really arise. If you have a single volume in your PC with 200Gb free, a further problem is that most filing systems (and operating systems) have a limit of 2 or 4Gb per file. Getting round that means running MFS Tools on something like ext3 under a recent version of Linux. (Alternatively you can backup to stdout and pipe to 'split', which will break the backup into managable chunks - you still need 200Gb free on one volume, though).
If you have all that, note the following: -Ta (some people seem to prefer -aq, but AFAIK, that's the same thing) means 'include all streams', so modifiers like -f and -l, which includes streams that would normally be dropped have no effect (because those streams will be included anyway by -Ta).
Compression is pointless as the recording streams are already heavily compressed and are therefore essentially random data. The reason compression works so well on 'compressed' backups is that vast swathes of the data that ends up in a compressed backup consists of long strings of zeroes. (You'll notice that the difference between -1so and -9so is just 2 or 3 percent - most of the data is either incompressible recording streams or blank).
Therefore, the only practical way, IMO, to backup a TiVo is to use dd or MFS Tools to copy whole drives or drive sets to new drives (which must be at least as large as the originals, naturally).
So, generally, you end up having to work without a backup and just be VERY CAREFUL when working on your drives. You won't lose the TiVo, of course, as you still have a compressed backup, but you might lose the recordings.
Please do not PM me asking for TiVo backups. I don't have any.
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