sudo smartctl -a /dev/yourssd
You’re looking for the Media_Wearout_Indicator which is a percentage starting at 100% and going to 0%, with 0% being no more spare sectors available and thus “failed”. A very important note here, though, is that a 0% drive isn’t going to always result in data loss.
Unless you have the shittiest SSD I’ve ever heard of or seen, it’ll almost certainly just go read-only and all your data will be there, you just won’t be able to write more data to the drive.
Also you’ll probably be interested in the Total_LBAs_Written variable, which is (usually) going to be converted to gigabytes and will tell you how much data has been written to the drive.
Uh, don’t do that if you expect your mail to be delivered.
Multiple PTRs, depending on how the DNS service is set up, may be returned in round-robin fashion, and if you return a PTR that doesn’t match what your HELO claims you are, then congrats on your mail being likely tossed in the trash.
Pick the most accurate name (that is, match your HELO domain), and only set one PTR.
(Useless fact of the day: multiple A records behave the same way and you can use that as a poverty-spec version of a load balancer.)