Reply to: What is it with CDR/CDRW/DVDR/DVDRW ?

[2BIT]

Yeah I have looked into that. As usual with IT, the situation is needlessly complex. Apparently the quality of the disc depends, at least to some extent!

totally agree, trying to show someone non savvy how to burn a cd properly - getting them to understand all the steps and then watch the burning fail at the last minute is probably the single biggest reason cd burning never took off other than the whole mp3 thing..

I think looking back CD's were just tulipe, far too easy to scratch and tracks skipping should be outlawed!

[Sysman]

I used to enjoy working on vacuum column and capstan drives, they required some real engineering skill, but were impressive in a sci fi / Billion Dollar Brain sort of way

I remember the vacuum jobs. One model a customer had was useless for recovery logs because it leaked and lost the vacuum.

But give it a decent sized backup to go at and whoosh it was fast (for those days anyway). You could hear it sucking data off the disks.

Baking analogue tapes to read them - I had a tour of a tape recovery company once. They specialised in preserving the data from geological survey tapes and digitising them. What appealed to me was the survey process - lobbing dynamite off the back of a ship to get the sound echos was definitely a job I could have enjoyed.

[TykeMerc]

9 track tape - Wikipedia, the free encyclopedia

Gosh.

I remember that stuff.

It was ever so impressive if one of the reels fell off.

Tape everywhere.

I used to enjoy working on vacuum column and capstan drives, they required some real engineering skill, but were impressive in a sci fi / Billion Dollar Brain sort of way

[PAH]

I don't think saving compressed files is a good idea at all, unless you save a shedload of PAR files with them.

An alternative to PAR files is to use Flexraid, which uses a similar principal and is free. It's primary use is to create a parity HD (matching the size of the biggest HD in the set) for (in effect) an unlimited number of HDs, so much more space efficient than most current RAID offerings.

The interesting bit is that it can also be used to create a parity disk for DVDs or external HDs.

For long term archiving of mostly static data Flexraid looks to be a great solution. I notice from the link there's a flexraid 2.0 out which may have even more/better options.

[Sysman]

Aye.

The theory was that those optical disks can last 50 years - what a joke.

We are now buying LTO-5 en masse. Soon we might have a vacancy for Milan ...

Sensible move. What backup software do you use?

I was reading about rewritable DVDs the other day. Apparently they degrade at room temperature, albeit slowly.

What other things should I consider in using optical media for backup?

Do not use rewritable optical media for long-term or archival backups. Rewritable discs use a phase-changing metal alloy film for recording data that is less stable than the dye used in writable discs. Burn your archival backups to writable optical media, using CD-R media when feasible given the variability in recordable DVDs reported by NIST.

(NIST is the US National Institute of Standards and Technology. Follow the link to read more)

All very well recommending CD-R, but Windows Server 2008 plus Active Directory climbs to just short of 20 GB once all the patches are applied.

[amcdonald]

RW discs degrade with each use

I dont get problems with write once discs and Ive got some about 15 years old now

But my strategy has been to back to cd or dvd and later when a hard disc gets too small to be usable, use it for archiving content on the assumption theres less risk of both a hard disc and a cd/dvd being unusable

[OwlHoot]

Reliability seems better the fewer saves you do, so now I always zip what I want to save.

Unless you're talking about those Iomega (?) zip drives, I don't think saving compressed files is a good idea at all[*], unless you save a shedload of PAR files with them.

The snag is that it only takes one or two bytes to degrade and the whole ZIP/RAR file is useless, whereas saving text files or images uncompressed often means that small glitches have less of an impact or almost none.


(*) Unless you're talking about some cyclic backup strategy, where the ZIPs won't be hanging around for years.

[xoggoth]

Over several machines have found them extremely unreliable. Use once is fine but use the option to treat like a hard disc and they soon stop working after a few saves. Reliability seems better the fewer saves you do, so now I always zip what I want to save.

[AtW]

Tapes degrade over time as well. I'd be surprised if they are rated for more than 15-20 years.

Indeed, that's why you take annual backups.

HTH

Milan

[PAH]

watch out if you plan to use them for anything other than storing some worthless photoes...

Yeah, I don't really trust anything anymore, including online storage.

Even HDs are susceptible to magnetic forces if there's a big increase in solar activity, so the only way to be safe is a mixture of SSD, HD, and paper!

Two NASes in different physical locations and regularly synced, is my current best effort at preserving my digital collection for the foreseeable.

[doodab]

Why is writeable disc (CD/DVD) technology so tulipe?

It's a consequence of the die or material used. You'll find even blank ones "go off" after a while. How long they last depends on the quality of the disks and how they are written and subsequently stored. Leave one in the sun and it'll be stuffed in a week or two.

For CDs, you can get archival ones made with a different die that cost a bit more e.g "HHB" HHB CD-R74 Gold (10 Pack) at Studiospares

Alternatively, you can make marks in clay tables and bake them. They have a pretty long shelf life.

Aye.

The theory was that those optical disks can last 50 years - what a joke.

We are now buying LTO-5 en masse. Soon we might have a vacancy for Milan ...

Tapes degrade over time as well. I'd be surprised if they are rated for more than 15-20 years.

[AtW]

Flash USB sticks typically use poor quality flash chips that don't make the grade into proper SSDs, watch out if you plan to use them for anything other than storing some worthless photoes...

[PAH]

I find that these are going the way of the floppy. The prevalence of USB ports in many devices, including home entertainment such as DVD players, TVs, mean that it's easier and more reliable to use a flash drive or external HD.

I too found CDs and DVDs I burned within the last 5 to 10 years that became unreadable due to deterioration of the dye (not surface damage), so did a big transfer of them all to a NAS.

Not really sure what the advantages of writable/rewritable DVDs are these days other than maybe cost per GB.

[AtW]

Aye.

The theory was that those optical disks can last 50 years - what a joke.

We are now buying LTO-5 en masse. Soon we might have a vacancy for Milan ...

[Bwana]

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