If it's just for the wallet file (and it's a BACKUP, not your only copy), that should be fine. Most drives go through issues after repetitive reads/writes or due to being filled up past their "true capacity" (some drives are altered to make them think they have more room than they do). If it's just for a wallet file, a cheap USB drive should handle the job of allowing access without causing too many issues. Just keep in mind that it can wipe at any point.