I just thought I'd throw out there a bit of info on Chkdsk vs. SMART. Reading the smart data from the Hard drive is entirely different than using chkdsk. Chkdsk is a software level program used when windows ' thinks ' there is data on a sector that it cannot read anymore. Either the drive is physically bad in those areas or at the time windows wrote data to the drive and then later tried to read said data it couldn't. So Chkdsk tries to read that data and create files of that data. If that data happend to be a system file then you will probably have other issues. If that data was say a song or some word document then you may have lost some of that data.
chkdsk is a good indicator or tool used to determine weather there are any bad sectors and if they are found wndows updates the FAT (file allocation table) and tells it hey these sectors are bad.. dont write data here anymore.
This doesnt mean the drive is failing. It could be that when data was being written that for whatever reason /power surge/brownout/got nocked around/Heavy machinery outside caused too much vibration .etc... something caused that data being written to fail. And it could be that those sectors were always bad. How many people buy a new computer and run a complete scan of their hard drive just to see how its going to perform. (probly only me)
The Hardware SMART test is reading what the drive itself thinks is going on. It has no idea what windows thinks. And it doesn't care. Because at the hardware level it uses it's own ' software ' to find and fix and mark and move and report any issues.
There may be nothing wrong with the drive at all. It's just you have some bad sectors which in my experience are on about 90% of drives out there.
Here is more info
taken from Here:http://www.wdc.com/wdproducts/library/other/2579-850105.pdf
In S.M.A.R.T. technology’s brief history, it has progressed through three versions.
S.M.A.R.T. I provides failure prediction by monitoring certain online hard drive activities.
S.M.A.R.T. II improves failure prediction by adding an automatic off-line read scan to
monitor additional operations.
S.M.A.R.T. III not only monitors hard drive activities but adds failure prevention by
attempting to detect and repair sector errors.
Western Digital has implemented all three versions of the S.M.A.R.T. reliability monitor on its hard drives.
Data Lifeguard is a unique feature to Western Digital's latest generation of high-performance
Enhanced IDE (EIDE) hard drives—the WD Caviar AC13200, AC24300, AC26400,
AC38400 and AC310100. While the S.M.A.R.T. System provides early warnings to pending
hard drive failure, Data Lifeguard actually helps prevent such failure. It uses the more than 90
percent of the time that a hard drive is idle to prevent data loss and reduce field failure.
How Data Lifeguard Works
Data Lifeguard automatically identifies and repairs sectors before data loss occurs. It performs
off-line read surface scans while the hard drive is idle, and refreshes weak data. The overall
hard drive performance is improved because error recovery is performed off-line during idle
times. The feature initiates automatically every eight operating hours for daily protection,
with the goal of performing one scan per day.
Specifically, after the hard drive has had eight hours of spin time and 15 seconds of idle time,
Data Lifeguard performs an off-line scan of all user data sectors. The spin time counts only
the time the hard drive is actively spinning. The idle time is defined as the time the hard drive
is not performing a host-initiated command. If the off-line scan is interrupted by a host com-
mand or power cycle, the scan will resume at the point where it left off after 15 additional
minutes of spin time and 15 seconds of idle time. Power cycle and power management events
do not reset the spin time counter, and the counter resumes counting after the next spin up.
The time it takes to complete an entire off-line scan is proportional to the size of the hard
drive; for example, it takes about 16 minutes for a WD Caviar AC310100 10.1 GB hard
drive. A vendor unique command is available that will indicate if an off-line scan is in
progress, and also provide the percent the scan has completed.
Data Lifeguard’s off-line scan—the same as implemented for S.M.A.R.T. III—identifies and
repairs marginal sectors. When the off-line scan encounters an ECC Firmware Correctable
Error, it runs a Sector Test to determine if a media defect exists. If one does, Data Lifeguard
rewrites the corrected data back to the original sector, then rereads it to ensure that the sector
is fixed. Data Lifeguard also protects future data to be written to suspect sectors.