The advantage of getting a hot-swappable enclosure is it’s fully automatic. You can put in a new blank drive and it’ll start cloning it, without the computer ever knowing. You can pull out a drive (maybe close programs first) to get a snapshot of the drive at that time.
My “friend” is wary of any system which is fully automatic. One of his main concerns is a virus which corrupts his data without him even knowing it.
That seems like a rather expensive snapshot, no?
No. Tell him to use a dedicated backup program. A good one will compress the data before copying it, and will copy only those files (or portions of files) which have changed since the last backup. The time savings here will be significant.
For example, I use a program called DAR to periodically back up my data to an external drive. The first time I do a backup takes over an hour, but every subsequent backup (about every two to four weeks) takes only ten minutes, since DAR writes only the data which has been changed. DAR probably isn’t an option for your friend, but there are doubtless similar programs for his operating system.
Indeed. Use a proper dedicated backup program.
Backup every day. A business cannot afford to lose more than a day of work. Really less than that, but a day is about all that is practical. Personal stuff, and people might manage a little longer, but most people would be peeved if they lost the last two weeks email.
Something not mentioned is the actual amount of data churn. How big is a daily incremental backup? The OP says 50 to 100 GB total data, but the amount that changes each day significantly affects a useful strategy. For many cases, although incremental backups tend to get bigger the longer you are away from the baseline, the time you can usefully go just taking incrementals can be very large. If data churn is not large it becomes viable to keep a permanent record of daily changes, so that it is possible to select the state of the system at any time in the past. The Apple Mac OSX Timemachine system does this. There will be proper Windows equivalents. This may be the best solution. But it must be implemented with proper resilience in the backup media, with multiple copies of data, and off site storage. And occasional permanent archiving. Belt and braces.
Also, any real backup strategy tests the system from time to time. Actually go through the steps and recover your working data from backups to a new disk. Make sure you can do this, and you have not made some sort of mistake in the process. Do it from time to time to ensure that you have not got a problem somewhere. Proper backup systems should provide a way of checking this. I used to teach system admin, and in the course used the very real example of a company that only discovered that their tape drive was defective when they came to read back their backups - finding a rack of blank tapes. The business failed soon after.
Well this is hardware, so it’s not susceptible to viruses. Plus, since you swap disks, even if the current one is compromised, your friend can fall back to the last one.
It’s not expensive, since the hard disks are reusable.