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.

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.

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.