Tape Backup

On 14 Jan 2005 08:06:40 -0800, "Irwin" wrote:

Arno,

Why are CD-R and DVD+-R unreliable and short lived?

CDR and DVDR are more reliable if verified, as you stated, but the
long-term life of them is unpredictable. If you're only counting on
them for 3 month lifetimes, you're probably OK, but if you want them
to last for a few years or more, you're playing with fire.

I like using HD as the primary backup, then archiving the backup files
to DVDR every now and again. This gives you several levels with
different failure mechanisms, and the DVDRs don't age enough to be a
very high risk.


--
Neil Maxwell - I don't speak for my employer

Neil Maxwell writes:
CDR and DVDR are more reliable if verified, as you stated, but the
long-term life of them is unpredictable. If you're only counting on
them for 3 month lifetimes, you're probably OK, but if you want them
to last for a few years or more, you're playing with fire.

High quality CDR (e.g. Mitsui Archive Gold) have undergone a lot of
testing and seem to be quite stable for long periods. The jury is
still out for DVDR. Hard drives contain all kinds of seals, filters,
lubricants on mechanical parts, and flash memory parameters and
firmware dependent on floating charges, all of which can decay over a
period of years. Hard drives are quite unreliable for long term
storage.

In article ,
Neil Maxwell wrote:
On 14 Jan 2005 08:06:40 -0800, "Irwin" wrote:

Arno,

Why are CD-R and DVD+-R unreliable and short lived?

CDR and DVDR are more reliable if verified, as you stated, but the
long-term life of them is unpredictable. If you're only counting on
them for 3 month lifetimes, you're probably OK, but if you want them
to last for a few years or more, you're playing with fire.

I like using HD as the primary backup, then archiving the backup files
to DVDR every now and again. This gives you several levels with
different failure mechanisms, and the DVDRs don't age enough to be a
very high risk.


--
Neil Maxwell - I don't speak for my employer


The ability to read a DVD written on one brand of burner on any other
reader scares me. I'd do a readback on at least one PC of another
brand to test it.

You also need several generations of backup, and never overwrite your
best backup. (this applies to disks and re-writable media.)

Unless you've actually tested a restore to bare iron you don't
know if your disaster recovery plan will work when you need it.

These days I do image backups to a pair of big disks in another
computer on my LAN, (these disks are synced in case one dies) and I
backup my data (mostly "My Documents") with some sync software that
keeps my laptop in sync with my desktop machine.

test test test .

--

a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

In comp.sys.ibm.pc.hardware.storage Irwin wrote:
Arno,

Why are CD-R and DVD+-R unreliable and short lived? I really don't
know.
My personal experience and that of people I know. The shortest CD-R life
I had so far was 5 minutes. It burned. It verified fine, 5 minutes later
the same drive could not read it. The problem is not so much that all
media are bad, but that quality and durability varies widely with no
way for the user to know which media are good and which are not. In
addition the burner/firmware/medium combination makes a huge difference.

You say HDD are reliable and medium life.

Medium = 5..20 years. The HDD manufacturers only state 5 year component
life. The problem is that there are components on HDDs (e.g. electrolyte
capacitors) that have a limited lifetime, even more so when unused.
Also part of the reliabaility claim is that you can suffer a complete
media loss if you drop them.

I have never dropped a
hard drive, but I have dropped a lot of backup CD-R, and I am guessing
that the CD-R tolerate physical abuse a lot better.

Yes: Mechanical on the underside. No: Scratches on the top, sunlight.

Now granted, I have
burned many a Drive Image CD, only to find that they don't verify
correctly. I never did understand where exactly the problem was in
that, was it software, burner, or medium?

All three (if you count the firmware of the drive as part of the software).

I guess that would qualify as
unreliable. It was be pretty devastating to try to restore a CD-R image
only to find that it was invalid and was your only backup. Actually, I
think that has happened to me before, I seem to remember. Is a
validated CD-R still unreliable and short-lived?

In my experience, that is unfortunately so.

I have some old HDD on a shelf in anti-static bags, and I don't
consider them particularly convenient. Also, how long does a HDD hold
data before it starts to corrupt?

Data corruption should take 10 years. However HDDs for backups are
best done with the HDDs in removable drive bays or UDB/FireWire/SATA
external enclosures, which also protect the drive so some degree.

Arno
--
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"The more corrupt the state, the more numerous the laws" - Tacitus

In comp.sys.ibm.pc.hardware.storage Paul Rubin wrote:
Neil Maxwell writes:
CDR and DVDR are more reliable if verified, as you stated, but the
long-term life of them is unpredictable. If you're only counting on
them for 3 month lifetimes, you're probably OK, but if you want them
to last for a few years or more, you're playing with fire.

High quality CDR (e.g. Mitsui Archive Gold) have undergone a lot of
testing and seem to be quite stable for long periods. The jury is
still out for DVDR. Hard drives contain all kinds of seals, filters,
lubricants on mechanical parts, and flash memory parameters and
firmware dependent on floating charges, all of which can decay over a
period of years. Hard drives are quite unreliable for long term
storage.

Indeed. The only good solutions for long-term storage is professional
tape intended for long-term storage (check the specs), MOD and (to a
lesser degree, since it is newer technology) DVD-RAM.

If you don't drop or overheat them, HDD reliability if fine for
regular backups. (Backup != long-term storage.)

I agree that DVD+/-R(W) is unclear at the moment. However the
German computer magazine c't does regular tests of burner/medium
combinations and has burned disks evaluated with professional
equipment. It does not look good. The same "speed before
reliability" marketing-driven philosophy that we know from CD-R
seems to be the current trend there.

Arno
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"The more corrupt the state, the more numerous the laws" - Tacitus

In comp.sys.ibm.pc.hardware.storage Al Dykes wrote:
In article ,
Neil Maxwell wrote:
On 14 Jan 2005 08:06:40 -0800, "Irwin" wrote:


You also need several generations of backup, and never overwrite your
best backup. (this applies to disks and re-writable media.)

Common consens here is 3 or more independent media sets in rotation.
If you keep backups for a longer time, add media sets. And be prepared
to have to restore from the second-newest set.

Unless you've actually tested a restore to bare iron you don't
know if your disaster recovery plan will work when you need it.

Not a media reliability issue, but very true! I had to do this once
(it worked), and since then I try this once a year or so with a spare
disk to be sure.

These days I do image backups to a pair of big disks in another
computer on my LAN, (these disks are synced in case one dies) and I
backup my data (mostly "My Documents") with some sync software that
keeps my laptop in sync with my desktop machine.

So-so from the point of reliability. Should be o.k.. Good for
convenience.

test test test .
And be sure what you actually test for!

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
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"The more corrupt the state, the more numerous the laws" - Tacitus

In article ,
Paul J. Hurley wrote:
Has anyone here tried any of the online backup solutions offered by
some ISP's? Essentially you pay a monthly fee for a block of storage
(500MB, 1GB, 2GB, 5GB, whatever) on a server located "somewhere" and
some software that runs in the background on your local machine that
uploads files after changes, compressed and encrypted of course. The
advantage is that all of this is automated and there is no additional
hardware to deal with. This can be a disadvantage as well.

Opinions?


I know people that have been using ibackup.com for several years
and I can recommend it. It's great for user data,
but it doesn't replace image backups for bare iron reinstalls
unless you are just writing MSWord docs and can sit down
on any PC with an internet connection to do your work.

It's "one touch backup", at least the way my friends
use it.

The access-your-data-anywhere is a nice feature.

You can get an ISP account with 500MB or more disk space
for a few bucks a months and use FTP to upload a ZIP
file of your documents.

For a business contigency plan, I'm sure that a responsible
online backup service has a EULA that should be read that lays
out terms and liabilities.

(no financial relationship with ibackup. I just see it used
on a daily basis.)



On 14 Jan 2005 15:00:22 GMT, Arno Wagner wrote:

In comp.sys.ibm.pc.hardware.storage wrote:
I am looking for opinions on what a decent tape backup for a PC
workstation might be, somewhere around 40 gigs or so, speed is not the

----
Paul J. Hurley
Caliban Computing
http://www.Caliban.com/
Spam resistant return email address.


--

a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

Paul J. Hurley writes:
Has anyone here tried any of the online backup solutions offered by
some ISP's? Essentially you pay a monthly fee for a block of storage
(500MB, 1GB, 2GB, 5GB, whatever) on a server located "somewhere" and
some software that runs in the background on your local machine that
uploads files after changes, compressed and encrypted of course. The
advantage is that all of this is automated and there is no additional
hardware to deal with. This can be a disadvantage as well.

If it's just a few MB, that might work pretty well. Transferring 5GB
over a typical broadband connection will be pretty slow. Also, I
don't know any of those services that provide encryption on the client
side by default. You have to supply your own.

In article ,
Paul Rubin wrote:
Paul J. Hurley writes:
Has anyone here tried any of the online backup solutions offered by
some ISP's? Essentially you pay a monthly fee for a block of storage
(500MB, 1GB, 2GB, 5GB, whatever) on a server located "somewhere" and
some software that runs in the background on your local machine that
uploads files after changes, compressed and encrypted of course. The
advantage is that all of this is automated and there is no additional
hardware to deal with. This can be a disadvantage as well.

If it's just a few MB, that might work pretty well. Transferring 5GB
over a typical broadband connection will be pretty slow. Also, I
don't know any of those services that provide encryption on the client
side by default. You have to supply your own.


The daily upload would be _really_ slow on an adsl line,
but some smart software that only sent modofied files would make
the best of things (or someting that works in background.

--

a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.

In comp.sys.ibm.pc.hardware.storage Paul J. Hurley wrote:
Has anyone here tried any of the online backup solutions offered by
some ISP's? Essentially you pay a monthly fee for a block of storage
(500MB, 1GB, 2GB, 5GB, whatever) on a server located "somewhere" and
some software that runs in the background on your local machine that
uploads files after changes, compressed and encrypted of course. The
advantage is that all of this is automated and there is no additional
hardware to deal with. This can be a disadvantage as well.

Opinions?

It is surely a good solution for a single off-site backup if
a) confidentiallity is really ensured
b) you data volume is low

It is not a replacement for a backup with several independent media
sets, unless the online service does that type of backup on the
storage, the cycle time fits your needs _and_ they allow you access
to older backups.

Arno
--
For email address: lastname AT tik DOT ee DOT ethz DOT ch
GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
"The more corrupt the state, the more numerous the laws" - Tacitus