Cd Backups Aren’t Forever

[waldwolf]

Unfortunately, magnetic tape is not the ideal media for long term data storage.

Magnetic tape degrades by known chemical processes. When the kinetics of these processes is fully understood, the degradation mechanisms can be modeled and the life expectancy (LE) of tapes can be estimated. The binder systems used in today's tapes are generally based on polyester polyurethanes. These polymers degrade by a process known as hydrolysis - where the polyester linkage is broken by a reaction with water. One of the by-products of this degradation is organic acids. These organic acids accelerate the rate of hydrolytic decomposition. Furthermore, the acids can attack and degrade the magnetic particles.

Note in the above chart*, humidity is more important in determining the lifetime of tape, than the storage temperature. For example, at 20° C (68° F) and 50% relative humidity (RH), an estimated LE value of ~30 years is indicated. If the storage temperature is raised to 25° C (76° F) at 50% RH, the LE is reduced to ~10 years. However, if the humidity is raised to 80% at 20° C (68° F), the LE is reduced to ~5 years.

Of course, when the earth's magnetic field does its next "flip", most magnetic storage material will be erased anyways. Recently, NASA scientists studying the earths magnetic shield report a growing "weakness" which may indicate another "north-south flip" of the poles is beginning.

Is this one of those new "Non volatile" memorys ?

I read somewhere, unlike flash (which is volatile), the Non volatile

memory products will have an almost unlimited lifetime...

The SanDisk SSD shown earlier uses non-volatile memory, however, sone brands do use volatle memory.

waldwolf

* Source: National Media Labs

[sensei]

Hard drives work best, if possible keep data on two separate hard drives,

at the very least, divide one into two partitions.

What's happens if your HDD fall down, or get a power shock, or a short circuit, let say: just some mechanical defect which crashes your HDD forever? 2 partitions? GONE!! All Data? GONE!!

What now?

The most reliable storage I use is MO-Drives and that the last 20 years! I having still MO-Disk 128 MB which are 20 years old and full fuctional!! Never was loosing Data on MO Disk. If the Drive gone? Doesn't matter, I've the Data Disk!

You've got a point there

MO-Disc are tough enough to withstand a nuclear bomb...

Well, maybe not that though, but it sure can handle the rough moves of a secretary who was a wrestler before.

It's a reliable backup that has a life expectancy of 40 years tops...

your data stays safe that long and it doesn't get f*cked up easily.

But one question though,

How many personal computers do you know has a built-in drive for a MO-disc?

[astral]

It is not only rewriteable cd's that will fail.

When the CD was first announced we were told it would last for ever,

but CD rot is a well documented phenomenon.