Data Storage - digitally

[gl556tr]

I am looking for a reliable means of Data Storage - digitally. Are data stored on ALL optical media in a compressed format? I think CDs are, as are DVD-R & DVD-RW. But what about DVD-RAM, where assorted modi (XP, SP, LP, EP) -- are they ALL compressed, too?
Are there various means of data-storage for HDDs? I am sure there are forms of data-compression available here. But I am need to find a means of storing data with NO compression whatsoever.
Also, optical media are not reliable for periods longer than 10 years; HDD are far better - how many years?
Finally, is there any other method of storing one's data long-term (apart from using stone!)?

[ChuckFickens]

data is stored however you want when you put it on any storage media, if you put compressed data on them then it's compressed, if you don't put compressed data on them it isn't compressed. So you can store uncompressed data on any medium you want.

Archive quality optical media will last far longer than 10 years if it's stored properly (in the dark is the main thing to look out for)

and In theory a hard drive would outlast you (and me) if it's stored in a safe location and not used.

As with any backup, if you are really worried about it you use two backups stored in separate, safe locations.

Now, all that said, you've not said what sort of quantity of data you'd want to store, the best way to store 10MB of data safely is going to be different to the best way to store 50TB of data!

[gl556tr]

Hello ChuckFicken,
Hope I've spelt that right.
Many thanks for your fast and detailed reply. I am looking at saving/storing up to 2 TB of data.

I am not altogethe happy with your statement that one can store uncompressed data on any medium I wish. Any? I'm sure that is not the case for optical media. Unless I am unaware of a means of forcing data to be stored always uncompressed.

I wholeheartedly agree about using double backups kept separately - and safely!

[rojash]

"Unless I am unaware of a means of forcing data to be stored always uncompressed."
You don't need to force it to be uncompressed. If you copy data directly to optical storage, then it will be uncompressed by default. Perhaps you are confusing the fact that we use the term DVD to describe both the physical media and the specific format for Digital Video. So, if you create a DVD in the video sense, the video and audio will be compressed. But if you copy data to a DVD it will by default be uncompressed.

[ChuckFickens]

I'm not sure where you're getting the idea that data on optical media is compressed.

If you have a 100MB file and burn it onto a CD it's still going to be 100MB on the CD, the only exception to this is if you are using some form of backup software which is compressing the data for you, But standard burning software does not compress data onto optical media.

2TB is a fair amount of data to backup and kinda rules out optical media, you'd need over 400DVDs! So you are going to be limited to hard drive backups (or tape, but the drives are bloody expensive then, i.e. £1000+)

For a semi reasonable price I'd be tempted to invest in 2 of these
http://www.google.co....aw8YnvDA&ved=0CBcQrRI

Stick two x 2TB drives in each one setup as RAID1 (simple mirroring) and copy your data onto each one and store them separately somewhere, you'd then essentially have four copies of your data so even one drive failed in each box you could still read the data.

(you could save the cost of the drive boxes by just copying the data onto four hard drives, but then you'd have to find a decent way to store them, putting them in boxes helps to keep them safe)

[VHG]

Just to backup what Rojash and Chuck said.

Data copied to another media (be it CD, DVD, external hard drive etc) does not "magically" become compressed, unless you ask for it to become compressed.

So if you have 2Tb of data to backup then you need 2Tb of media to store it to.

You could consider a BluRay drive, as a BluRay disk can hold 25Gb single layer, 50Gb dual layer (though you will still need quite a few BluRay disks).

However you would need to buy a BluRay "drive" and then the BluRay disks which are more expensive than normal CD and DVDs disks.

Note that some files are already in a compressed format (like mp3 files or jpeg files) so if you have a lot of them and you want to compress them then you will not gain very much as they cannot be compressed much more.

[gl556tr]

Your second reply containing the link is very helpful, and certainly better than shuffling optical storage disks no matter what their capacity.

What has been most satisfying is the knowledge that data is stored 'as is' unless one uses a burn SW that forces compression. Yes the RAID 1 setup seems most interesting, most robust.

One point, though, I do not --yet-- have 2 TB of data, but will have once I have scanned many documents and photos + slides. I have plenty to do!

Thank you all for your support.