[nSLUG] [NSLUG] Re: USB stick for backup okay?

Daniel MacKay daniel at bonmot.ca
Wed Mar 28 17:00:32 ADT 2018

All media — spinning magnetic, ssd, tape, floppy optical — fail.  Some fail more predictably than others - the two worst I’ve worked with were a horrible thing called a ZIP drive, and 8mm tapes in Exabyte brand drives. Both of those had high failure rates and VERY poor compatibility: that is, you’d have an Exabyte drive fail, take your spare off the shelf and discover that it couldn’t read any of your backup tapes.

In terms of philosophy, this is an oldie - twenty years old? or more? - but a goodie:


It doesn’t matter what medium you use, if you follow the Tao of Backup.

Practically, this is what I do:

My Macs get Time Machine’d to a local hard disk. Time Machine does (something like) a week’s worth of once an hour, then a month’s worth of once-a-day, then one a week forever. I have two Time Machine disks; Norval has the other one backing up his Macs at his office; every month or so we swap drives so if a drive gets destroyed by a flood or fire, there’s an older offsite one.

My production Unix machines all back up, via rsync, to an antique Solaris box in my basement running rsync (again, for physical separation.)  Every night the backup machine does a ZFS snapshot of the backup volume. A script deletes those snapshots with a “Towers of Hanoi” algorithm: there’s a backup a day old, two days old, four days, eight days, 16 days etc.

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