From Newsgroup: alt.os.linux.ubuntu
On Mon, 8/19/2024 9:45 AM, Monsieur wrote:
Interesting, I did not know that. I better start backing up my backups then, because all my disks are cheap ssd's.
If you clone a 1TB SSD to another 1TB SSD, and write the output device
from end to end, that uses one cycle on the flash cells. The flash cells
are rated for about 600 cycles. You could clone 600 times, before the
SSD would be worn out.
Hard drives on the other hand, you can sit around all day,
doing one dd transfer after another. On the better hard drives,
they're 550TBW, which means you get the same ability to use
the disk, but you get that much runtime per year. I have one
hard drive, with 55000 hours on it, but it's not a 550TBW drive.
The poorest quality hard drive, is 110 TBW (WD Blue perhaps), the highest quality
hard drive is 550 TBW. High capacity drives (perhaps 8TB capacity),
are filled with helium gas and sealed, unlike the other drives
which "breath air" through a breather hole which is equipped
with a hepafilter. The 24TB helium filled drive, should never experience effects from room humidity, but then, the helium filled drive
can fail when the helium escapes. Some helium drives, the theory is
that they have pressure gauges. But decoding the indicator,
I don't think anyone has figured out for sure what the
values mean.
They're quite different kinds of devices. The HDD, you can use it
any way you wish. You are more likely to be exhausted while
using it, than the drive would be. SSDs last a long long time,
doing small file writes, but if you made a habit of blasting
large images, over and over onto an SSD, that's not really
all that good for it.
Someone did a "life test" on a small selection of SSDs. In terms
of calendar time, it took quite a while to wear them out. The
end-of-life policy is different on each brand. You must be
especially careful with Intel branded SSDs. If the device has
a rating of 600 writes per NAND flash cell, as soon as the
Intel drive hits 600, it "bricks". It will neither allow
reads nor writes. This is particularly bad as a policy, as it
does not allow simply cloning over to another Intel drive.
Instead, the user must have a clone copy they made *before*
end-of-life. This means, owners of Intel SSD drives, must
check with smartmontools or similar, what the recorded write
life is so far.
The most liberal brands of SSD, they whiz right past 600 and
continue to both read and write. You might get a substantially
longer life. Or, you might have a catastrophic failure (black
screen some morning, no boot for you). Such a device though,
if you were paying attention, you might still successfully
clone it, if some system utility were to warn you about
the dire situation (risk taking). I treat these drives as
the more desirable kind, because as long as you can monitor
them for remaining life, there should not be any data loss,
and not an obsessive need to do backups all the time.
My backup frequency on SSDs here (lazy) is a full backup
every three months. Images go to an 18TB hard drive. I only
own one Helium drive so far :-) The Helium is "guaranteed"
to stay inside the drive for five years. The gas seals
are done with an adhesive! While the housing has welds,
the welds are not for gas, they're for mechanical protection
of the inner seal plate. This means data recovery on my
18TB drive (if I wanted to pay for such), is fraught.
As a joke, a data recovery company made a video of them
using an NC machine to mill the welded plate off the
top of the drive. It ... almost worked (you have metal shavings
everywhere too). With ordinary (air-filled) drives, you just
open them in a portable glove box with hepafilter. Helium drives,
are an entirely different animal. Again, the user is challenged
by their technology choice. But I decided to buy *1* of them for test.
An air-filled hard drive, has on the label "do not block this hole".
That is the breather hole. On a Helium drive, there is no hole
like that in the top cover, and there is not a warning of that
sort to be seen.
Helium drives, the altitude spec for them is the same as
the air-breathing drives. But it's possible they do in fact
operate at higher altitude than the old drives could.
Air breathing drives always work at room pressure. As the barometric
pressure changes, room air enters or exits the housing, through
the hepafilter. If you unscrew the lid on an air breathing drive,
there is no popping sound, no vacuum evident, no pressure evident.
We don't know what the pressure level is in the Helium drive.
They would fill it to sufficient level, so the flying heads work properly.
Paul
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