Are server backups to flash drives feasible?

If I were to use a flash storage device on a server, a portable one specifically, and backups written to it periodically every 5 hours or so, would there be much wear to the flash drive to the point of depending on it as a reliable fallback to data recovery? Since there wouldn't be a lot of writing involved all the time, the flash drive's lifespan isn't reduced that significantly right?

Or maybe somehow in addition, get the filesystem driver to use fresh blocks for all allocations instead of old ones to maximize flash cell lifespan?

Reason I want to do this is to avoid using up bandwidth for network backups, and there aren't any other local servers to perform such backups without overall internet latency. And that flash storage devices are cheap and easy to obtain.

NOTE: I'm no hired IT, I have a low budget and run a home server if that's any specific. Also I'm looking to backup are web directories and SQLServer DBs.

I probably wouldn't rely on flash drives for server backups. I just wouldn't trust the reliability.

If you have no network storage then you could purchase USB hard drives for the backup. We use external USB hard drives for backup drives. We copy to a machine that has a large internal drive and then use a robocopy script to replicate to external USB drives that are swapped out each day and rotated. I have also done this for clients with drives directly attached to server.

I've had some experience with failed flash drivers, and usually the main problem was the controller, not the flash chip itself, but I still wouldn't use it for main backup.

Flash chips usually have limited write cycles, so you can overwrite each 'sector' only times (~10.000). If you write one backup per day, that's a long, long time. If you write logs there, or copy something every couple of seconds (or have a /tmp dir there), that's not going to last long. Most newer controllers have wear leveling, and change the location of blocks (they have a couple of them extra), so the wear is distributed across the whole flash chip.

Using it as an extra backup, with sequential writes (no often overwriting), might be a good idea, but i woul definitely keep my "main" backups somewhere safe (hdd raid, or tape, or both).