On 19/03/2019 02:30, rhkra...@gmail.com wrote:
Is anyone (reading this list) using USB Flash / Pendrives or [micro]SD cards for backup? I've thought about doing that, especially as they continue to come down in price, but my experience with them at least in some cases has not been good. The worst case seems to be dash cams where, after about a year or so they just stop working, but I've had at least one similar case using them for data storage.
I have six 16 GB ext4-formatted USB 2 flash drives of two models that I rotate for daily local backups. Each backup is about a 3 GB gzipped-gpged-gzipped-tar file, so the write pattern is large sequential writes. The outermost zero-compression gzip ("pigz -0") allows a keyless 32-bit checksum test with any gzip implementation. Each thumb drive contains no more than three backup files at a time. All are checksum-tested after each backup.
I have been using these drives for at least five, and perhaps more than seven years. My rough estimate is that I have written around 60 times their capacity to these drives. I have had one drive fail, about five years ago.
My rules for USB flash backup are: (1) nothing gets written to USB without first being encrypted because failed drives cannot be erased without physical destruction, and (2) nothing gets written to USB without a checksum because USB drives are unreliable and will happily and silently corrupt data.
Redundancy and the expectation of drive failure will reduce inconvenience when it occurs. And it will. But you have to be able to detect it.
I also have offsite backup in the cloud with the same encryption and integrity measures (plus cloud encryption), and retention of longer-term archival backups. Now that I have gigabit fibre, offsite backup is faster than local.
Kind regards, -- Ben Caradoc-Davies <b...@transient.nz> Director Transient Software Limited <https://transient.nz/> New Zealand
