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Topic: digital storage: hard drives vs cdr\'s vs cdrw\'s (Read 6225 times) previous topic - next topic
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digital storage: hard drives vs cdr\'s vs cdrw\'s

CD-Rs seem to be reliable only when using Taiyo Yuden (or very few other manufacturers like Kodak). Question 1: are CD-RWs more or less reliable in terms of long-term storage?

Question 2: How do hard drives score in terms of long term storage? Do disc sectors 'die' like on cd-rs, or can one state that 'data placed on a hard drive will still be there in 50 years' ? Of course, probably depends on brand etc..

any ideas?

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #1 –
1: Nobody can really tell, due to the lack of long-term experiences. Lab tests with extended UV light and heat exposure predict a CD-R durability of 5 to 10 or more years and a CD-RW durability of 10 to 30 years. In the past, some manufacturers claimed 100 years for CD-Rs, but this is marketing hype.

I personally would use CD-Rs, and burn important data from them to new CD-Rs every 2 years.


2: Hard disks are usually built for 2 to 5 years usage at most. Agreed, a lot of them will run longer than that, but everything longer than those few years is a bonus, and not calculated by the manufacturer. The disks can develop bad sectors as well as physical damage to the mechanical parts. The magnetic field of the earth will have almost no effect on reliability; today's write/read methods (Giant Magnetic Resistance and so on) are safe in that respect. It will all more or less come down to physical failures.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #2 –
Thanks for the answer 


Basically what you're saying is:

CD-RW > CD-R > hard drives

..for long term storage. However when using the hard drive (like an extra external drive) just to store data, and not reformat every month, defragment, and whatever you could classify under 'intensive use' of a hard drive, a hard drive could hold the data for a longer time.

Small note: disk failure on your 80 gig HD = lose all data whereas cd-r failure = lose 700 megs.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #3 –
Hmm, I've always thought  CD-R lasted longer then CD-RW?

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #4 –
Quote
Originally posted by CiTay
2: Hard disks are usually built for 2 to 5 years usage at most. Agreed, a lot of them will run longer than that, but everything longer than those few years is a bonus, and not calculated by the manufacturer. The disks can develop bad sectors as well as physical damage to the mechanical parts. The magnetic field of the earth will have almost no effect on reliability; today's write/read methods (Giant Magnetic Resistance and so on) are safe in that respect. It will all more or less come down to physical failures.

From what I know, HD manufacturers give only MTBF (which doesn't mean much, really -- average time until the drive fails?).  I've seen very few modern HD's fail due to physical reasons, many more seem to fail due to problems with supporting electronics on the drive.  You may be right that "planned obsolescence" is a factor.

I've never encountered a bad sector on a non-MFM/RLL drive.  But even a single bad sector is a good indication to replace the drive immediately, as it's probably about to show a catastrophic failure.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #5 –
It's just a drop in the ocean, but I got some CDRW dead after 6 monthes (data no more readable), and some CDR after 3 years.
In my work, I have 270 hard drives in charge, about 5 years old. There are some from time to time that fail. The result is often straight and plain :
"Error : impossible to load command.com" !
They run night and day in bad conditions (dust, heat).

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #6 –
MTBF = 'Mean Time Between Failure'. And, yes, once you start to get bad sectors it is time to replace the drive. It is a common misconception that hard drives suddenly fail. Normally, they don't. They die over a period of time, and the occurrence of bad sectors is a good indication of impending doom!!

If you are writing to CD-R/CDRW, bear in mind that most hifi CD players will not recognise CDRWs. The reflectance is insufficient.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #7 –
Quote
Originally posted by john33
It is a common misconception that hard drives suddenly fail. Normally, they don't.
Well, that "rule" doesn't seem to apply to IBM harddisks... 

(Sorry but they are really really bad... Wouldn't recommend them to anyone, unless you like to gamble... )

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #8 –
Quote
Originally posted by john33
MTBF = 'Mean Time Between Failure'.

I knew that, but what I meant is that the designation doesn't say too much.  It's like saying "this volcano is overdue to erupt" or "the Earth is overdue to have an asteroid hit."  Seems to me that hard drives typically last a lot longer than the MTBF figure, rather than shorter (it could just be an illusion due to being technologically outdated before reaching MTBF hours). 

It helps to keep them cool of course, supplied by a good PSU, and never move a HD while it's operating....

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #9 –
A lot is down to how you store the things - a CD-R out on the shelf is not going to last long (corrosive air can get into the layer below the plastic), if it is in an airtight box out of sunlight then they will last longer - maybe even 100 years.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #10 –
Quote
Originally posted by Sachankara
Well, that "rule" doesn't seem to apply to IBM harddisks... 

(Sorry but they are really really bad... Wouldn't recommend them to anyone, unless you like to gamble... )


It's only about ONE series of these ... the (in)famous DeskStar 7200RPM drives manufactured in Hungary (if i recall correctly) - i hade the bad luck of owning one. but there's a bright side to it - when it broke i had to re-encode my music collection to LAME - and now to MPC

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #11 –
what about writable dvds? what is the life expectancy of those? or is it to early to start using them for archive?

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #12 –
In my experience, hard drives are far more reliable than CD-R's.  I've had countless CD-R's go bad within 6 months, whereas I've never had a single hard drive fail (my oldest hard drive is now 9 years old and still running fine, with no bad sectors).  Even without inherent reliability problems, CD-R's are much more likely to be physically damaged (scratched, left out in UV light, etc.), whereas you really have to bang a hard drive hard to physically damage it.

The only advantage I can see in CD-R's is that the amount of data you lose per failure is less.  On the other hand, the amount of space you need to store all that data is lots lots more, and the convenience is far lower (it'd be a real pain in the ass to backup a 160 GB hard drive onto 250 CD-Rs).  I currently don't use backups, but if I were going to (and had some spare money), I'd run a RAID setup (either RAID1 or RAID5) for transparent redundancy.  Another option would be simply periodically copying to a spare drive that you keep in the closet, but hard drives are actually less reliable when infrequently used than when continually used.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #13 –
Quote
Originally posted by Delirium
(it'd be a real pain in the ass to backup a 160 GB hard drive onto 250 CD-Rs). 

Luckily, in most cases it isn't necessary.  Backup data that can't be replicated (like Emails, documents, etc).... programs can be reinstalled and compressed music files can be recreated.  I have a 60GB HD, and my main system backup uses about 350 megs.  Other stuff I back up onto CD-R as I go, and are not part of any main system backup.

For anyone who wants the convenience of an "instant restore" (& possibly greater speed) then Raid is a great way to go.  For the rest of us, CD-R is IMHO still adequate.  It would be a pain in the tail to recreate & reinstall everything, but entirely possible. 

Another option is a second hard drive and Norton Ghost used on a regular basis.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #14 –
Quote
Originally posted by fewtch
Luckily, in most cases it isn't necessary.  Backup data that can't be replicated (like Emails, documents, etc).... programs can be reinstalled and compressed music files can be recreated.  I have a 60GB HD, and my main system backup uses about 350 megs.  Other stuff I back up onto CD-R as I go, and are not part of any main system backup.
That's true, assuming that compressed music was recorded from CDs you own.  Now of course none of us here download music from the internet or rip CDs from friends (heh), but for those who do, backing up MP3s/Oggs/etc. might be a concern.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #15 –
Quote
Originally posted by Delirium
That's true, assuming that compressed music was recorded from CDs you own.  Now of course none of us here download music from the internet or rip CDs from friends (heh), but for those who do, backing up MP3s/Oggs/etc. might be a concern.

Even for those that do, why not just back it up gradually onto CD-R as it "becomes available?"  I constantly see these cases where someone's hard drive dies, and they lose all their music... I don't understand it, when CD-R's are so cheap & burners are so fast. 

Buy a spool of 50, backup each time a new 700MB or so of stuff "appears," and just put the CD-R back onto the spool with some labeling scheme (by number perhaps).  Keep a separate folder on the HD for "new, unbacked up stuff" that never exceeds 650-700MB.  Not too hard.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #16 –
Quote
Originally posted by fewtch

Even for those that do, why not just back it up gradually onto CD-R as it "becomes available?"  I constantly see these cases where someone's hard drive dies, and they lose all their music... I don't understand it, when CD-R's are so cheap & burners are so fast. 

Buy a spool of 50, backup each time a new 700MB or so of stuff "appears," and just put the CD-R back onto the spool with some labeling scheme (by number perhaps).  Keep a separate folder on the HD for "new, unbacked up stuff" that never exceeds 650-700MB.  Not too hard.
I suppose that'd work, I'm just too lazy to burn CD-R's all the time.  As I have 70GB of mp3s currently, it'd take me forever just to burn the 100 CD-R's worth I currently have.

As for the other stuff you mentioned that doesn't take up much space (emails, documents, etc.), I just back those up onto other hard drives.  My system currently has 3 hard drives in it, and the very important documents are mirrored on all three.  This is probably more reliable than a CD-R, and it also ensures that my backups are easy to keep up to date (instead of either using a CD-RW or periodically throwing out the backup and burning a new one).

I suppose my main problem is that I don't trust CD-Rs at all, because in my experience they're terribly unreliable and very easy to damage to the point where they're unreadable (in my drive anyway).  Perhaps if you stored them in a case in a dark place they'd be more reliable, but they seem completely useless for everyday use (about 70% of the CD-Rs I've burnt as audio CDs or data CDs and used regularly have died within 6 months, whereas not a single one of my purchased non-CD-R audio or data CDs has).

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #17 –
Perhaps it's your burner that's making the cd's unreliable.  I've yet to have one cd become unreadable or unrecoverable in two years (if you don't count the one i dropped out of my car and stepped on).  And half of the time I use cheap cdr's for audio cos it's just for my car (Imation, Memorex, CMC).
"You can fight without ever winning, but never win without a fight."  Neil Peart  'Resist'

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #18 –
Quote
Originally posted by fewtch

I've never encountered a bad sector on a non-MFM/RLL drive.  But even a single bad sector is a good indication to replace the drive immediately, as it's probably about to show a catastrophic failure.



ALLL harddrvies have badsectors when produced they are just hidden from the user throug the fyssical adressing of the platter.

so if we where to follow your rule we hade to replace a drive as soon as it was bought

many utils "out there" has the optiosn to hide badsector and replaced them with a new sectot that are good. (IBM drive fitnees test and AMIdiag). just like the manufactor does


--- In short --
NO drives are produced without bad sectors.
Sven Bent - Denmark

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #19 –
I've had CD-Rs that were unreadable just a week after being burned (damn cheap, no-brand CDs!).

My HDD (Quantum Fireball) is 5 years old and it still works fine though.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #20 –
I've had similar experiences with no-brand cdr's some years ago. Now I use brand cdr's and have had no more problems of that kind. I use Imation cdr's but I guess that if you are concerned you can use even better quality cdr's.

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #21 –
Quote
CD-R durability of 5 to 10 or more years and a CD-RW durability of 10 to 30 years


hmm i'm not so sure about this. i thought the concensus was that cdrs were more reliable than rewriteables - i've certainly had more problems with cdrws. but then again maybe i'm using the wrong brands

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #22 –
Among the hard drive failure I've got, I'd say 3/5 were no more bootable, so, being part of a very important workstation, we didn't check if there were bad sectors on them, they were immediately replaced.
1/5 of them showed bad sectors after errors like "reading impossible from C:"
1/5 died instantly : "hard drive failure, press F2 to enter setup"

digital storage: hard drives vs cdr\'s vs cdrw\'s

Reply #23 –
Quote
Originally posted by Pio2001
Among the hard drive failure I've got, I'd say 3/5 were no more bootable, so, being part of a very important workstation, we didn't check if there were bad sectors on them, they were immediately replaced.
1/5 of them showed bad sectors after errors like "reading impossible from C:"
1/5 died instantly : "hard drive failure, press F2 to enter setup"

That holds with an opinion I've read (and agree with) that supporting electronics are the main cause of HD death, not mechanical-related failures.