On 17/11/18 17:11, nospam wrote:
In article , Tim Watts
wrote:

The cheaper way is to copy to a decent make of SD card or external SSD
disk (less chance of mechanical failure) but the downside is you really
need to have a yearly regime of checking all devices are readable and an
X-yearly regime of "copy to new device" - even SSDs fail with age.

using sd cards is *not* cheaper, *not* practical and not reliable. a
bad choice all around.

I disagree on all 3 counts. On what basis do you make your arguments?


using an ssd for backup purposes is a waste of money because the speed
advantages are lost. use an ssd for the main drive and spinners for
backup purposes.


You missed the point - spinners are mechanical. They are prone to damage
due to shock (handling and dropping) and if used for offline archival
purposes, run the risk of seizing if left unpowered for long periods
(years).

SSDs lose the mechanical problems which greatly increase the reliability.

But even so, I wouldn't put any device in a drawer and forget about it
for several years, but if I did, I'd bet on the SSD and flash cards
being more likely to still work.


Ideally all files should have a checksum file written with them (MD5,
SHA1 or anything reasonable) and this used to verify files on an annual
basis.

that's automatic with modern file systems.


No it isn't.

The only common filesystems with *file data* checksums are ZFS, BtrFS -
both linux (and one also Solaris).

exFAT has only metadata checksumming.

The rest with file data checksumming a SquashFS, ReFS, NILFS and NOVA
and of those, SquashFS is the only one I've seen anywhere in use.

So yes, you really need to run a checksum generator at the start and
that is the only way you can be reasonably sure your data has not
suffered corruption.

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