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Cost of DVD as data storage versus HDD (UK)



 
 
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  #11  
Old October 13th 04, 03:22 PM
Major ChrisB
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"David X" wrote in message
anews.com...
What is the cost of DVD storage in the UK? I am in the UK so my figures
reflect UK prices. I want to store data not music.

I would welcome any comments on my posting.


(1) I can buy a 160GB hard drive for approx 65 including delivery.
(E.G.
Maxtor Plus9 160GB 8MB 7200rpm from Dabs).
The available formatted space on the HDD is about 150GB (in 4K block with
NTFS), so this comes to 41p per GB.

Sustained data transfer rates are fast (about 15 MB/s according to
http://storagereview.com/map/lm.cgi/str and
http://www.pcguide.com/ref/hdd/perf/extSpeed-c.html) so the process of
getting data to or from the HDD is relatively quick.


(2) For CDs (not DVD) I would say the usable storage space is approx
500MB
(not 750 or 800 because it is rare to completely fill a CD and I believe
there is approx 10 percent used for error correction). I don't know what
block size is used.

I want to have a protective case and not use the very cheapest product.
100
cased CD-Rs is approx 22 including delivery. I need 300 to match 150GB
so
the total cost is 66. This excludes costs for the CD-R burner.

Data transfer rates when reading are not bad at about 3 MB/s (according to
http://www.pcguide.com/ref/cd/perfTransfer-c.html).


(3) DVDs. Now this is new to me. Are the following reasonable
assumptions.

Cased DVD+R or DVD-R 8x blanks are about 0.50 each (?).


Possibly but have a little patience and get a slightly slower speed. I got
4xdvd-r disks 100 for 19 works out 19p per disk or about 5p per gig.

while it is 4.7Gig dvd-r You can fit about 4.4gigs of data on one and I can
burn the whole thing in about 15 minutes.

Printable surface with no logos to you can lable them how ever you want or
simply write on them for easy archiving.

I would easily choose dvd writing over hard drive storage.

19 gets you 100 disks on a spindle, plus I got a 240 space cd/dvd holder
for about 3 which keeps them scratch free and easy to store in a space
about 30cm long and about 10 cm wide...



  #12  
Old October 13th 04, 06:25 PM
GSV Three Minds in a Can
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Bitstring s.com, from
the wonderful person David X said
What is the cost of DVD storage in the UK? I am in the UK so my figures
reflect UK prices. I want to store data not music.

I would welcome any comments on my posting.


Don't cross-post to so many groups (many people kill anything
crossposted to 3 places, on the assumption that if the OP doesn't know
which group it goes it, it won't be of much interest in any of them).

Back to the question .. cost per byte is not an interesting metric for
backups, unless you include the cost of making the backup and the cost
of securing it against whatever disaster you are backing up against.

For HDD failure protection, the simplest solution (and cheapest) is
'second copy' to another drive elsewhere on the network, or even on the
same PC. The downside is that many disasters apart from a disk crash can
take out both copies (theft, fire, lightning). The other downside is you
only have one identical copy, so there is no archival ability (e.g.
'oops I trashed that file yesterday, it's been copied to the backup
which is now trashed too, I need a copy from last week).

For proper backup you need an offsite copy .. tape or DVD or CDR will
all work, just make sure you can read the backups on whatever machine to
may need to restore them on. Tapes can be picky about being read on
other machines, and can be picky about being read at all if badly stored
for a long time. Another option is 'backup across the www' to a storage
server in a secure location .. they'll be backing that up to tape,
hopefully.

Unless you have large capacity tapes, it is pretty stupid to back up
anything more than critical data. People gaily make disk images of their
whole system, but unless you can produce =identical= hardware this is of
no use at all if your original system is stolen, burns to the ground, or
whatever. If you have the original applications on CD, or you can buy
new copies from MS, there isn't much point in wasting time and money
making copies every day/week for the rest of your life.

In a perfect world, RAID1 or RAID5 for continuous up-time even if a disk
crashes (which they are increasingly prone to do), tape backups of
anything that can't be reproduced easily .. daily ones, or weekly, or
whatever turns out to be the best tradeoff between 'cost of prevention'
and 'cost of recovering what you hadn't prevented being lost'.

--
GSV Three Minds in a Can
Outgoing Msgs are Turing Tested,and indistinguishable from human typing.
  #13  
Old October 13th 04, 06:32 PM
Neil Maxwell
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On Wed, 13 Oct 2004 13:43:08 +0100, nospam
wrote:

That said, media cost is one of many considerations and only becomes
significant when you have a real lot of data. Both media have significant
pros and cons, there is no clear winner. Personally I use both.


I believe this is the best solution.

HD provides fast, automatable, inexpensive, high-capacity, hands-off
backup, but you have all your eggs in one basket, susceptible to power
supply failures, viruses, user error, mechanical failure, theft, etc.

DVD is slower, needs to be started and loaded manually, requires more
media, and is susceptible to dye degradation, disc delamination, UV
exposure, and such, but can easily be stored off-site, can be kept in
multiple versions, is easy to transport, etc.

It's relatively inexpensive to use both for data you really care
about.


--
Neil Maxwell - I don't speak for my employer
  #14  
Old October 13th 04, 06:40 PM
Neil Maxwell
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On Wed, 13 Oct 2004 08:16:17 -0400, "Locutus"
wrote:

I will say that a dvd will last 100 times longer than an HDD


There is no data to support this. Since recordable DVD storage is a
relatively new medium, it will be some years before we know if it has
the same dye degradation problems CDRs do (though it appears that it
does, based on early reports). Even then, the dye and reflective
layer formulations are constantly being changed, so data valid on 2
year old 2.4X media is not applicable to today's 8X media.

Plus if the HDD dies you lose ALL your data
unless there is a fire you will not lose all the DVD/CD,s


These are true, and DVDs can be stored off-site as well.

DVD/CD's are easier to transport,will handle shock,moisture and all other things that will kill an HDD


DVDs are susceptible to shock and flexing causing the two
polycarbonate layers to delaminate from the data layer. Moisture can
cause problems with the dye layer if there are any gaps in the edge
seal. Also, leaving one sitting in the sunlight will kill it quickly.
We don't even know all the failure mechanisms for DVD yet.

So in conclusion DVD/CD storage is cheaper in the long run


More like the risks and costs are different between the two media.


--
Neil Maxwell - I don't speak for my employer
  #15  
Old October 13th 04, 07:07 PM
Arno Wagner
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In comp.sys.ibm.pc.hardware.storage Locutus wrote:
Im not going to comment on the "cost per" quotes you made
I will say that a dvd will last 100 times longer than an HDD


This is very unlikely at present. Have you read any DVD quality tests
recently? For some products you get 50% defectives right after the
burn!

Plus if the HDD dies you lose ALL your data
unless there is a fire you will not lose all the DVD/CD,s
DVD/CD's are easier to transport,will handle shock,
moisture


No. There are already instance of CDs being dertoyed by fungus!
And in addition DVD/CDs have a real problem with sunlight/

and all other things that will kill an HDD
So in conclusion DVD/CD storage is cheaper in the long run


This strikes me as _very_ naive.

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


  #16  
Old October 13th 04, 08:12 PM
Arno Wagner
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In comp.sys.ibm.pc.hardware.storage David X wrote:
What is the cost of DVD storage in the UK? I am in the UK so my figures
reflect UK prices. I want to store data not music.


I would welcome any comments on my posting.


[...]

Overall, I get the impression that HDDs are a far better and cheaper way of
backing up data for the home user. The HDD can be re-used and if the HDD is
plugged in (which can be harder than inserting a DVD) then the availability
is almost instantaneous.


Your calculation is missing one point: Redundancy.

If your Disks are e.g. in a RAID5 and are surface-scanned every 2
weeks, the sytem is going to be very reliable and your overhead will
be one disk per array and some hot/cold spares. Additional costs
include hardware, power and system administration.

If your disks are kept offline, you have to take into account
the possibility of catastrophic failure of one/several disks
and should actually have all data at least on two disks. This
still might give less reliability than the first solution,
depending on storage time/conditions and the disks. If the
disks are tested periodically, reliability will increase but so
will cost.

For your CDs/DVDs you also should put everything at least on
two media. If you do regular checks of the media, reliability
will increase, but so will cost. Also reliability figures
for CDs/DVDs are much less certain that for HDDs. The
30 years or even 100 years or more ofteh quoted by many
vendors 5 years ago have turned out to be wishful thinking
in many instances. It is better today, but nobody really
knows how much better. CDR and DVD+/-R are young technologies!
No long-term experience like with HDDs, Tapes or MODs exists!
And of course while the RAID5 has very low handling overherd,
you will be juggeling CDs/DVDs for hours to burn them, verify
them and generally handle them.

Of course, depending on the reliability wanted, you can do more or
less replication and you should have off-site copies for anything
important. You cannot simply take the media price. Storage cost is a
trade-off between cost, efort (also cost) and reliability. And you
need reasonable reliability estimates and estimates of needed
reliability and storage volume to make an informed decision.

Arno
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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


  #17  
Old October 13th 04, 11:28 PM
Dorothy Bradbury
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I'll throw a spanner in the argument...
o You probably need both media types as backup
o Altho the accurate extent depends on the data's importance

One media type is 1 single point of failu
o The DVD drive may produce bad recordings or those only it can read
---- a replacement may have difficulty reading old disks
---- DVD media could go the way of CDR media - variable
o The HD drive may fail, and is a single-instance of the *entire* dataset
---- a single backup of an entire data-set is a lot of risk

Suppose you used just DVD, and you lost the original HD:
o You have 150GB to restore, using 30 disks
---- using & restoring via CDR would be akin to floppies
---- plus if say 1 in 100 disks goes bad, you may find 1-1.5 are bad (*)
o That is going to take say 30hrs to achieve
---- and 30hrs to recreate if the data-set changes regularly

So you may want to consider:
o What part of the data-set is important?
---- data that can be regenerated is ok on HD
---- data that is absolutely critical requires redundant backups (copies)
o How often does the data-set change, or sub-sets of it change?
---- DVD-R gets more expensive the more often change is required
---- DVD-RAM whilst rewriteable & better is more expensive

So the economic answer may be HD for the bulk backup, then spread
the DVD-R cost over several months with incremental backups etc.

Another issue is whether you will backup frequently enough:
o It is very quick & easy to backup a HD to another HD
o It is a very different matter to backup to DVD-R

Whatever backup method you use, verify files regularly.
Not so long ago I had to get data off a CDR, Kodak Gold & TDK
from some years back - quality brands. More recent readers would
not read it - and a laptop drive the least, and even less with heat. It
turned out I could read the data ok, in chunks, from a freezer. As
soon as the CDR warmed up XP did the usual I/O Block Error (7).

The backup media that is most reliable is 2 different types :-)
The backup may not even exist unless you verify it - often.

One reason why companies have used cheap SATA drives.
Appliance - Near-Line storage with integral tape drive
o Faster backup to disk, then dumping out to tape
o Two backup media copies, near-line archiving re fast search/recovery

RAID is not a backup - it is availability :-)
--
Dorothy Bradbury


  #18  
Old October 14th 04, 12:31 AM
Arno Wagner
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In comp.sys.ibm.pc.hardware.storage Dorothy Bradbury wrote:
I'll throw a spanner in the argument...
o You probably need both media types as backup
o Altho the accurate extent depends on the data's importance


One media type is 1 single point of failu
o The DVD drive may produce bad recordings or those only it can read
---- a replacement may have difficulty reading old disks
---- DVD media could go the way of CDR media - variable
o The HD drive may fail, and is a single-instance of the *entire* dataset
---- a single backup of an entire data-set is a lot of risk


Suppose you used just DVD, and you lost the original HD:
o You have 150GB to restore, using 30 disks
---- using & restoring via CDR would be akin to floppies
---- plus if say 1 in 100 disks goes bad, you may find 1-1.5 are bad (*)
o That is going to take say 30hrs to achieve
---- and 30hrs to recreate if the data-set changes regularly


So you may want to consider:
o What part of the data-set is important?
---- data that can be regenerated is ok on HD
---- data that is absolutely critical requires redundant backups (copies)
o How often does the data-set change, or sub-sets of it change?
---- DVD-R gets more expensive the more often change is required
---- DVD-RAM whilst rewriteable & better is more expensive


MOD/DVD-RAM (similar technology) is very good for smaller backups
with high reliability requirements. Also for long-term storage.

So the economic answer may be HD for the bulk backup, then spread
the DVD-R cost over several months with incremental backups etc.


Another issue is whether you will backup frequently enough:
o It is very quick & easy to backup a HD to another HD
o It is a very different matter to backup to DVD-R


Whatever backup method you use, verify files regularly.
Not so long ago I had to get data off a CDR, Kodak Gold & TDK
from some years back - quality brands. More recent readers would
not read it - and a laptop drive the least, and even less with heat. It
turned out I could read the data ok, in chunks, from a freezer. As
soon as the CDR warmed up XP did the usual I/O Block Error (7).


The backup media that is most reliable is 2 different types :-)
The backup may not even exist unless you verify it - often.


Yes, that seems to bite a lot of people. And please compare
the data on the backup medium to the data on the main medium.
I have seen numerous occasions where there was corruption in
the transfer path. Only a compare will reliably show you this.

One reason why companies have used cheap SATA drives.
Appliance - Near-Line storage with integral tape drive
o Faster backup to disk, then dumping out to tape
o Two backup media copies, near-line archiving re fast search/recovery


Yery insightfull, all of these remarks. I do disagree a bit
about needing two different types of media. For not yet well
understood media like DVD+/-R this is certainly valid though.

RAID is not a backup - it is availability :-)


And ease of repair! The major reason I have now all
my /root and /home on RAID is I was getting very anoyed
wasting half a day of work until the system was usable again.
Of course that is also an availability argument ;-)

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


  #19  
Old October 14th 04, 01:12 PM
Daniel James
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In article , GSV Three Minds in a
Can wrote:
Don't cross-post to so many groups (many people kill anything
crossposted to 3 places, on the assumption that if the OP doesn't know
which group it goes it, it won't be of much interest in any of them).


aside
... and in doing so avoid a huge amount of junk and a few interesting
discussions.

I must say I'd find it "challenging" to dream up a post that could
legitimately be posted to more than about five groups, but I don't think
four is necessarily out of order.

The OP selected four groups for a posting which seems to me to be
reasonably on-topic for all of them ... except possibly uk.comp.homebuilt
(which is where I'm reading it, as it happens) where it is a common enough
subject fr discussion, if not strictly on-topic.
/aside

Back to the question .. cost per byte is not an interesting metric for
backups, unless you include the cost of making the backup and the cost
of securing it against whatever disaster you are backing up against.


... and, perhaps more importantly, the value of the data.

People gaily make disk images of their whole system, but unless you can
produce =identical= hardware this is of no use at all if your original
system is stolen, ...


That's a good point, and one that's not made often enough.

If you have the original applications on CD, or you can buy
new copies from MS, there isn't much point in wasting time and money
making copies every day/week for the rest of your life.


Also true. One might think -- especially give the time it takes to install
some large applications -- that backing up once after an install would be a
time-saver, but in general when software is installed (on Windows, that is)
it sets a cartload of registry entries that aren't easily backed up in
isolation. Backing up the whole registry isn't useful if disaster forces a
change of hardware (which will mean the system-specific parts of the
registry will no longer apply). Reinstallation is really the only safe
choice.

That registry is a pain in the proverbial, sometimes.

In a perfect world, RAID1 or RAID5 for continuous up-time even if a disk
crashes (which they are increasingly prone to do), tape backups of
anything that can't be reproduced easily .. daily ones, or weekly, or
whatever turns out to be the best tradeoff between 'cost of prevention'
and 'cost of recovering what you hadn't prevented being lost'.


Good advice. Add to that that the daily/weekly backups (on whatever medium
they're made) should be test-restored so that you can be sure that they
*can* be restored, in the event of disaster (and that you've backed up
everything you need). Keep a spare device that can read the backups, in
case the original fails. Having a good tape backup regime is no good if,
when you need to restore some old data, you find that the tape drive is
knackered and that that type of drive is no longer available.

You can spend a fortune on backup and still not get it right -- and you
certainly can't get it all right without spending a fortune. How much you
do spend must depend on the value of the data.

Cheers,
Daniel.





 




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