Hey there,
My current HDD is a Samsung HD161HJ. I got it for about 3 years. About 1 year ago when I start up my computer it started showing "SMART command failed" at the POST screen. No biggie , I disabled the SMART feature and carried on. About 2 weeks ago , after returning from a trip, that I brought my computer with , at power on it started to make a long screech. I got a bit scared and turned the power off, and back on after a bit. Computer powered on normally , and HDD didn't seem to have any problems. But now , it makes that sound almost every time I start my computer in the morning ( after 8 or so hours of being off), but only if it was off for a long period of time.
I backed up whatever data I had so there is no problem of lost data, but I'm thinking that it will eventually fail on me. Am I right in thinking that? Anyone care to guesstimate when that will happen ?

The usual reason for a SMART failure is an excessive number of bad sectors.

Try a comprehensive SMART diagnostic. Look for reallocated, pending, or uncorrectable sectors.

HD Sentinel (DOS / Windows / Linux):
http://www.hdsentinel.com/

HDDScan for Windows:
http://hddscan.com/

See this article for SMART info:
http://en.wikipedia.org/wiki/S.M.A.R.T.

_________________
A backup a day keeps DR away.

Your drive will most definitely fail at that very moment when you realize that your most critical document is not backed up and you need access to it right away.

_________________
Luke
Recovery Force Donor Inventory: 5,000+ Fully Cataloged HDDs & Growing

"screech" = a sort of hiss that fades when the drive has reached target speed ?

No , it sounds more like the beep sound the computer makes when booting , only higher pitched , longer and a bit distorted. It usually goes on for 2 3 seconds then it does short beeps. I can't tell if the disk is spinning up/ has spined up or not at all , didn't put my ear to it to actually check it up. I am going to try and record the sound if I can and also listen if its spined up or not, but the thing is it didn't made the sound the last 2 days. Weird..

Can you tell me if the motor is Nidec or JVC and connected with flat cable or a pcb to motor contact ?

Its a Nidec , connected with the contacts on the pcb.