[nylug-talk] Recovery is not about media, but availability and storage -- WAS: backup media

[Alex Pilosov]

On Wed, 12 Mar 2008, Bryan J. Smith wrote:

> Alex Pilosov wrote:  
> > Another thing I wanted to bring up:
> > Backups on tape may be soon outdated, and we'll think of them as quaint
> > as punchcards.  The current HDD pricing is comparing very favorably with
> > cost of tape media.
> 
> Cost isn't typically why tape is still used as the preferred 5-10 year
> "off-line" medium.  Commoditization of disc has helped in the "cost"
> versus tape, but tape still "wins" on surface area, let alone "off-line"
> longevity and storage.
A very good question. Can you read 15-year-old tape today? I've done some
research, it isn't as simple as you think. You generally have
compatibility with 2-3, sometimes 4 generations of tapes, for "mainline"  
formats (some formats are just declared obsolete and nothing is backward
compatible).  Example, current "best" DLT-S4 drive can read SDLT-1 tapes.
Drive was released in '07, media was released in '98. That's only 10 years
of backwards compatibility.

Compare this with hard drives. Technology for the *interface* between 
drive and computer changes far less frequently than the tape media. Your 
20 year old SCSI-1 drive going to work just fine today. Similarly for ATA. 
Lifespan of a interface standard is ~20 years.

As far as off-line storage, I don't know. I frankly doubt that drives 
would be much worse than tapes, based on empirical experience of dusting 
off some old drives, but I don't know if anyone has done more specific 
research.

> Although 2.5" disc is gaining in popularity for shorter-term 2-3 year
> "off-line" usage.  E.g., some newer tape cartridge solutions are
> actually just commodity 2.5" disks packaged.  2.5" disks can handle
> almost as many Gs as a typical tape cartridge.
Only takes someone inventing a hdd tray with integrated shock mount. :)

> Alex Pilosov wrote:  
> > For example, 500GB HD is ~100$ (20c/GB).
> 
> A commodity, 3.5" HD is designed to be used on-line at least a few times
> a month, typically once a week at least.  Failure to spin a 3.5" disk
> can cause its low-cost, commodity materials to break-down.  E.g., Even
> most near-line backup solutions "spin" and "exercise" commodity, 3.5"
> HDs several hours at least once per week -- typically doing a checksum
> verification.
Sounds like bs, sorry. Reference, please.

> Alex Pilosov wrote:
> > I think we will see a very-very-low-cost huge HDD "storage" arrays (no
> > full access to all drives concurrently, instead, a backplane with
> > software-selectable access). I don't know of a product like that yet,
> > but I'm sure there'll be one soon (think low-cost "thumper"-like
> > chassis)
> 
> You mean the concept of the "Virtual Tape Library" (VTL) and the
> evolution of disk concentration into the "Massive Array of Idle Disks"
> (MAID)?
>
> The "Virtual Tape Library" (VTL) that has been around for almost the the
> last decade.  FalconStor VTL is probably the most proliferated solution,
> originally released on Red Hat Linux 7.3.
<lots snipped> It's not about the name. It is about pricing. Saying word
'storagetek' makes you fail, immediately. Currently, price of the
enclosure is still far higher than price of drives. When it stops being
the case, then you can say its "MAID" or whatever.

> Again, cost isn't the reason why tape is still more popular for an
> "off-line" medium.  Off-line longevity of 3.5" disc absolutely sucks,
> especially when it comes to taking Gs and leaving off-line for weeks.
> Commodity 3.5" disks aren't designed to be spun-down for long-periods.
> That's why many of them arrive DOA when they've been off-line for
> months.
Reference, please. 

-alex