Barely functioning HD, and seeking advice re: how to successfully record in blu-ray

[D. Hugh Redelmeier]

| From: Paul King <sciguy-Ja3L+HSX0kI at public.gmane.org>

(I've reformatted your message because it arrived rather broken up.)

| The 1TB Seagate I had been using and trying to recover data from is 
| being officially declared "pooched".

Sad.  Lot of disk stories end like that :-(

| The ddrescue program produced a 3GB file which is not mountable, and yes 
| I used "-o loop". 3GB out of half of a terabyte is not much, but it is 
| easily enough for email. The file has been kept, but at present it is 
| pretty much taking up space.

There are ways to sift for goodies without looking treating it as a
file system.  Of course the chances of your valuable bits being in the
1/1000th of the disk that you've got are small.

If what you want is mail, you could spend some time sniffing the
corpse with a low tech:

	strings -n 20 imagefile | less

| While I give out an enormous thanks for Hugh's advice and encouragement, 
| I think that I need to move on.

Likely wise.

| Most things can be recovered from 
| existing DVDs and CDs I have around, except they too are slowly 
| succumbing to bit-rot. My personal email must now be declared "forever 
| lost".

This bit-rot scares me.  I've been nervous about most affordable
backup techniques.  So I don't do backups :-) :-)

I recommend (superstitiously) to do backups on different media,
expecting them to have different failure modes:

- hard disks are cheap these days.  But losing 3T of backup may lose a
  lot of backups!

- I've had iffy second-hand experience with DVDs

- I feel most comfortable (not very comfortable) with CDs.

- I really don't trust USB flash drives.  They might be useful.

- for really important long-term stuff, paper is pretty good (low
  acid is a good idea; laser toner is probably pretty stable, unlike
  inkjet)

I think that the key is to be very careful about the stuff that
matters.  That turns out to be very low volume.  I mostly want to save
human keystrokes rather than megabytes of software.  Easier said than
done.

Annecdote: I remember discovering that my backup CDs were wrecked
after some years by the plastic window in the CD envelope welding
itself the the CD!

There are many failure modes.  It only takes one to get you.

| Luckily I have an LG Blu-Ray USB external drive with a Windows-based 
| burner that promises to back things onto fresh media. Except that I have 
| had a hard time with this.
| 
| Of 6 BD disks that spent several minutes in the bay with the progress 
| bar doing nothing, only to return a "burn failed" error, one may have 
| been successful. This is far worse a success record than when DVD 
| burning first came out. Since these are my first experiences with 
| recording on to BD media, I don't know if this is expected or not.
| 
| Is anyone able to suggest the conditions which will optimize the chances 
| for a successful burn? This is for files on an entertainment center 
| which is single-boot, unless you know of "live" distros which have k3b 
| or something similar. Meatime, I just thought of going back to my 
| Partition Magic (Slackware) DVD to see if anything useful is there.

I've bought a BLuRay burner (SATA) and will eventually install it.  One
trouble is that I suspect that BluRay will be no more reliable than
DVD.  One reason that I bought the drive was that it also
burns a new kind of archival DVDs (Millenniata M-Disk).  I don't
actually know how good M-Disks are; they are not cheap.

The chatter about burning BluRays under Linux looks worisome.  As
usual, cdrecord folks slag the forkers.  For previous fights, I've
found the cdrecord proponents quite over-the-top.  They may well be
right this time.

Anyway, blank BluRays are a similar cost/byte as hard drives:

BluRay: one 25G disk for $1 (may not be the best brand; what is the
best brand?).

Hard drive: 3T USB 3.0 external for $109 most weekends ($90 last
boxing day; may not be the best brand).

Hard drives are a lot easier to deal with.  But a lot more eggs in one
basket.

I've worried that a decent external BluRay drive ought to be USB3.0 vs
USB2.0.  But I haven't done the bandwidth math.  Lennart has often
pointed out that USB2 is very CPU-intensive.
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