Hard disk data longevity? My informal results

[Guest Keatah]

I had (still have) a 10meg disk mfg in the mid-1980's. It is a 10MB Sider. A disk nearly as big as a boom box! I recently powered it up sometime last year and it operated just fine. All the files put into it were still present and accounted for. I transfered all the stuff to the PC environment and ran a byte-by-byte comparison. Out of 900+ files, all were identical.

 

I ran the same test on a 27GB disk made in 1999 and while it had only 18GB worth of data, it compared 100% identical to files on my modern storage devices in use today.

 

I spot checked a box full of other disks from the 90's era and had the same results. Each of these disk's files tested good too.

 

These disks hadn't been powered up in years. And I'm inclined to believe that the disks (like their floppy counterparts) hold up much better than predicted. I didn't do anything special storage wise, I just put them in a bag, not even airtight, and had them sitting in a box in the closet.

 

I have several more GB sized (and one more 10MB Sider for the Apple II) which I'd like to push to 40 years. And see what happens.

 

I'm currently testing a 1TB dataset of all kinds of files. I'm comparing a static copy that has sat for several years against a copy that has been migrated over 6 disks and defragged by a good number of utilities, been through compression and decompression and disk imaging over and over again. So far 300GB into the test and no differences reported.

 

 

What are your experiences with data retention on magnetic media?

[Nergal]

unused (ie without weardown of heads) it is assumed magnetic HDD will last ~40 years

 

Edit: very sciencey explain

http://superuser.com/questions/284427/how-much-time-until-an-unused-hard-drive-loses-its-data

[Andavari]

unused (ie without weardown of heads) it is assumed magnetic HDD will last ~40 years

 

Until the Earth's magnetic field eventually causes so much corruption it's useless, but then again a 10MB disk in this day and age is utterly useless.

[Guest Keatah]

Simply re-writing the data isn't enough. While it will refresh *the* data & sectors. It won't refresh the servo markings - wherever they may be.

 

 

These servo tracks and markings.. These are written one time at the factory and never again (on modern disks). No amount of re-writes by the user or so-called low-level formatting freshens these. Once they fade, they fade!

 

It's different with the first stepper motor disks of the 80's. They don't have servo tracks and a low-level format writes ALL of the bits - fresh.

 

Thus I expect my Apple II HDDs to last into the next century.

[mta]

i've still got my first HD i purchased.

a 3.7gig (yep, that's written correctly) that i paid $400 for in 1992.

 

as you say @Keatah, a 10meg drive is useless now, 3.7gig ain't much better - not even for backups.

 

i plugged it in about 18 months ago, purely out of nostalgia and it still worked. there it was, a snapshot of my digital life.

with IDE ports on mobos getting rarer, i fear it'll be lack of access rather than the drive dying that will bite me on the bum first.

[Guest Keatah]

Let me rephrase that. A 10MB disk is useless for today's applications. For yesteryear's wares it rocked.

 

Would you believe that we still have an Apple II that is used for writing correspondence and personal journals? A 10MB disk is fine for pushing text around. That's 10 MILLION characters of storage online!

 

3 Million characters = 900 pages of text, more or less. Probably more. I'd guess we have almost 3,000 pages storage space. Much more if compression is used.

 

There's a certain charm using a computer from 1978, been in the family since we got it back then.

 

Eventually I'll just dedicate the 10MB disk to applications and store all our journal stuff on a flash disk. Yep. You can plug a USB keydrive into an Apple II.

 

Granted this is an unusual setup and certainly not mainstream. But like I say it has a charm all its own.

[DennisD]

This isn't exactly what you guys are talking about and apologies for the slight digression, but the issue of "size" came to mind as I was reading your posts.

 

Back in the day when my big kids were small kids we had an Amiga 500, and I bought it for them with a huge 1mb of memory installed. Not the measly 512kb's they came with.

 

After a while I increased this to 2mb, and my kids were the talk of the Saturday computer club ... "Look, they've got a 2mb Amiga". "Wow!" .

 

With 10mb disks you would have have been looked upon as a god like character.

 

How things have moved on.

[Guest Keatah]

I was indeed a god! My BBS was the hub of activity. And neighbors and friends I didn't know I had all wanted to see this 10MB disk in action. It really was the future!