Subject: Re: HD as backup (Re: RAID In general)
To: None <>
From: Greg A. Woods <>
List: current-users
Date: 04/18/2003 03:54:36
[ On Thursday, April 17, 2003 at 21:40:26 (-0400), Chuck Yerkes wrote: ]
> Subject: Re: HD as backup (Re: RAID In general)
> Not really.  I've LONG (like since 94) dumped to a spool drive
> then to tape.  I've setup excessively high performance RAID boxes
> to catch database dumps to keep downtime to a minimum.

Spooling to a big hold area does not solve the problem.

Except for your very last conceding paragraph I think you're still
missing the size/speed issue, and you're mixing unrelated or conflicting
issues together in a far worse way than you accused Greywolf of doing.

Even for the big professional shops with budgets for off-site backups it
doesn't matter how fast they can copy a big database to a holding disk
if it still takes them more than 24 hours to spin it onto tape.  I
recently saw a three-by-72U-rack RAID system fully populated with 3.5"
low-profile drives (~200 drives per cabinet, IIRC, probably 10-TB total)
sell on an auction site (for fractions of pennies on the original dollar
value, sigh).  Even with dedicated I/O channels and three or four DLT
drives it would still take a long time to back that sucker up onto tape
media.  If one was storing sensitive and often changing data on such a
massive system then it would probably be cheaper and easier to just drop
a whole mirror unit in some separate location as far away as one could
afford to pull fibre to and then just keep feeding each site with
replacement spare spindles to replace the dying drives (sort of like
regularly replacing the dead vacuum tubes in ENIAC :-).

These days ordinary people regularly fill 320GB and larger filesystems
on el-cheapo home and small office machines and they do want to back
them up.  Nobody's going to stuff that many DAT cartridges into their
drive even if they have the whole week off to do it.  There's also no
way you'll ever convince any such user to buy a brand new SDLT320 media,
let alone a spiffy new SDLT320 drive that costs way more than their
whole system, and on top of it all the extra high-speed controller
interface needed to keep it spinnning (assuming their consumer-grade
drives and I/O controllers can suck data out of a filesystem on their
lone big spinddle fast enough to feed an SDLT320 drive in the first

It's just not possible to economicaly back up modern high-capacity
systems to tape.  On the other hand with a couple of extra drives in
their own hot-swap cannisters and a foam-filled aluminum briefcase you
can rotate "mirror" spindles through and keep one safely off-site at all
times (even in your safe deposit box at the bank!).  Non-expert users
will still need better software to support use of this capacity as a
proper "virtual" backup subsystem (i.e. not just as a low-level drive
mirror), but that will come with time.

> The is both facetious and wrong.  And you know it.

Actually, no, I don't think so.

> DAT/8mm can take physical shock.

No, not really that much, especially not in certain directions.

>  Drop a DAT (in the pretty plastic
> case where they ALL live when not in a tape drive) from 20 feet.
> Onto concrete.  Bet it works.  Shuffle your feet on a rug and pick
> it up.  Bet it works.

I sure as heck wouldn't trust my most precious data on a long-play DAT
dropped from 20 feet, especialy not if it hit the wrong way.

As for your other tapes, well all I can say is you've been very lucky to
date.  I can probably still get the data from my old QIC-60 and QIC-150
tapes and maybe even the QIC-550's too, but I've had almost no luck at
all with older DAT tapes, and very little luck with older 8mm tapes.
I've always stored all my media with as much care as I can manage too
(fire resistant containers in cool and dry locations, careful handling,

> Hell, I've taken 3/4" UMatic video that were dropped in WATER and
> recovered them.

Now that's facetious.  You can practically recover the necessary parts
of an NTSC video signal off 3/4" industrial video tape with a magnifying
glass and tweezers.  You might as well compare it to recovering soggy
punched paper tape.

For backing up modern high-capacity systems we're talking about orders
of magnitude higher densities with even your DDS3 data tapes, let alone
the media for an SDLT320 or for any of the most modern high-capacity
Exabyte drives, etc.

Actually I've had better luck with hard-drive repair and recovery
services than I've ever had with attempting tape recovery.

> 8mm drive in a box.  QIC150 in a box.  Don't ahve a full PC to read the
> MFM.

I fail to understand why you think you'd need an old PC to read an MFM
drive.  There are dozens of other kinds of machines that'll talk to it,
and many of them probably still in production in some places.  My 3B2
and Sun-3 machines could for starters....  :-)

> Yes they are.  They are just in a box that reduces that.
> That doesn't make them less delicate.  It attempts to deal with
> their delicateness.

Now you're picking nits.  The point is that drives can quite easily be
protected well enough that they're not too risky to use to transport
backup data off-site.

> In 10 years, your drive will likely require a whole
> computer system from NOW to be read.  In 10 years, I will need a
> SCSI card to use my tape drives that are already 10 years old.

Unless you've got those boxed drives in a sealed rare-gas environment
then in another few years you'll need to re-manufacture all the plastic
and rubber parts in those drives before you can use them.  :-)

I think you've also missed the point about using disk drives for backup
storage (and even off-site storage).  We're not, or at least I am not,
talking about long-term archival storage in some closet somewhere.

I'm not planning to keep any old removable media for data storage, or
even on any particular vintage of disk drive.  I'm slowly loading all my
precious data onto live filesystems and I plan on keeping it there all
the time.  With modern storage trends I fully expect I will be able to
keep everything I want online all of the time for as long as I'll ever
want it, even if I do join the masses and start storing multi-media
data.  For disaster recovery I do expect I'll move to using low-cost
removable drives that I'll mirror my data to and then always keep a set
off-site, and I'll keep upgrading and replacing those drives as needed
so that I never have to rely on anything antique to access any of my
data.  For safety I'll also selectively backup the most important stuff
I have via network connections to remote systems where it'll also stay
online all of the time.

								Greg A. Woods

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