SMART and defective HDDs

Magnetic storage on hard drive is using statistics and heuristics to figure out the information stored magnetically. No reading is 100% perfect, that's why it has built-in correction mechanisms. The values you see here are statistical rates of error of various kind. They are of interest only when they exceed a specific value. Otherwise, it's normal for them to increase and decrease as the drive is working. There is no failure or imminent failure for any of the drives.

I'd be worried why WDs show those as zeroes all the time. At such a high data density (order of gigabytes per square inch), reading errors are bound to happen and the built-in mechanisms will correct them; nevertheless, they should be reported, not hidden just to make the user feel better with his/her choice of a hard drive brand.

Hi ruby90,

the issue with S.M.A.R.T is, that it is not smart at all :(.

The Read Error Rate is a very good example, that the numer does not tell you anything usefull:
Wikipedia: (Vendor specific raw value.) Stores data related to the rate of hardware read errors that occurred when reading data from a disk surface. The raw value has different structure for different vendors and is often not meaningful as a decimal number.

A good list of values can be found here with a rough explanation for each. Wherever it says vendor specific raw value, it means you cannot read anything useful from it without the background of what is encoded in there. Obviously WD and Seagate are using it different.
http://en.wikipedia.org/wiki/S…ATA_S.M.A.R.T._attributes

ruby90, the test tools are all for Windows, so you'll have to connect the drives to a Windows PC to run the tests.

Toshiba Diagnostic Tool - the Comprehensive Test takes about 2 hours and includes a surface scan. http://storage.toshiba.com/sto…upport/software-utilities

Seagate SeaTools: check the Seagate drive in the list, then Basic Tests > Long Generic, or Fix All > Long. http://www.seagate.com/support…ries/seatools-win-master/ (needs .NET 4.0)

Western Digital Data Lifeguard Diagnostic for Windows: run an Extended Test, including the surface test. http://support.wdc.com/product…groupid=608&sid=3&lang=en

Reallocated Sectors Count and Current Pending Sector Count are the ones to really worry about.... if you see those going up, watch out. bad sectors ahoy.