Hard Disk Sentinel analyses the S.M.A.R.T. attributes provided by the disk and by evaluating these values, creates and displays a textual rating. It may contain the number of problems encountered during the lifetime of the hard disk, the spin up problems, the data transfer errors, etc. The background color of this area (green, yellow, red) indicates the health of the disk. The text area may contain tips to correct the problems so it is recommended to read the details.
If the health level of the disk is below 100%, it does not necessarily mean catastrophe. The displayed health value is calculated by all problems ever found in the lifetime of the disk until now. Such problems are all recorded in the internal database (the S.M.A.R.T. table) of the disk and Hard Disk Sentinel software reads and displays them.
The first thing is to verify that these problems are still actual - or they were already fixed or the situation is already improved. For example, if bad sectors are displayed, they are not used any more by the hard disk and they cannot be accessed by any means (the spare area is used instead of the problematic sectors). That's why surface scanner applications (for example, scandisk) does not show any problems, because they also test the spare area (see below).
Also if spin up problem is displayed (which can be caused by weak power supply or problems with the main power line) and these are already fixed (for example, power supply is replaced or an UPS is installed) such problems are not significant any more.
The most important is to make sure if the hard disk status is stable or not: how the health value changes under high load and during long term use. If the health value is not too high but stable (does not change), the previously found problems can be ignored because the disk is not using the reallocated sectors any more and no new bad/weak sectors found (if the text description contains this).
The best method is the data-safe hardware self test of the disk which can verify if the current situation is stable. Different tests can be started from the Disk menu. Both examines the components of the disk (heads, servo, firmware, internal memory) and the extended test also verifies the complete surface area of the drive. If such tests complete without problems (even if the drive health is lower than 100%) then the situation can be considered stable.
If any (or both) tests report problems, it is recommended to use different method for extensive testing. A good example is to overwrite the complete disk surface (not only performing read test). This can be done by the surface tests available in the Disk menu of Hard Disk Sentinel. The best way to use the Reinitialize disk surface method but different tests are available to verify the disk surface. Write tests are better as they can effectively detect and repair problems.
If the health value and the displayed text description is constant, does not change
after the tests and for a longer time, the current problems can be cleared.
This way the software will not show them any more, just count new problems in the future use -
and until no problem is found the health value will be re-set to 100%.
To clear the existing problems, please open the "SMART" page of the disk and find the attribute(s) showing any problems (these are marked with ! sign). Click on the "Offset" column and enter a negative value, the same you can see in the "Data" column in this line (and in the text description of the drive). For example, if 5 reallocated sectors are displayed, then please specify "-5" in the Offset column for the corresponding attribute. Please check the temperature calibration page for more details about using offsets.
Anyway, it is recommended to continuously monitor such disks, especially, if two or more different problems and/or weak sectors displayed in the text description. Such monitoring allows to detect any (even small) new problem and gives the opportunity to perform a backup in such cases. The PRO version of the software can do this automatically.
If the health is low but above 0 %, it is not possible to ask for replacement in
conditions of warranty. At this point (regardles of the actual health or the
results of the test) the disk may have "too few" problems from the viewpoint of the
manufacturer - so usually they refuse warranty replacement.
Generally, warranty replacement is possible only if the number of problems are higher and reaches the threshold level defined by the manufacturer. At this point, the health drops to 0 %.
Important to know that serious testing (and especially the hardware tests) can reveal more problems thus can reduce the health value more.
Maybe it is possible to use the test application provided by the manufacturer to verify disk status. It is important to know that some of these do not really fix but only hide problems which can appear again at later use. That's why it is highly recommended to continuously monitor the disk after the test software of the manufacturer is completed - especially if the health value changes in any direction.
What is a "bad sector"? How they born and how they can be fixed? Users are confused because verifying the disk surface with software (for example by using Windows Scandisk) does not report any problems or bad sectors.
S.M.A.R.T. is constantly analysing the disk surface during normal operations. If it finds a problemmatic area (one or more sectors where the data is hard is hard to read or write), it tries to read the data and copy it (reallocate) to the spare area. The original location is then (internally) marked as bad and all further read/write operations pointing to the original location is then redirected to the spare area.
When the operation is completed, the original (bad) area is not accessible by software any more. Even re-install or complete re-format will not show problems because the original bad area is not used any more. That's why software (for example Windows' Scandisk) will not find problemmatic sectors. Only the hardware security erase function will access this area (clearing these sectors also).
That's why for example DOS "format" command will never show bad sectors on most modern hard disks because of S.M.A.R.T. (except if the spare area is full but it is really hard to find a such hard disk).
Reallocation of the sectors may be completed with or without some errors (hard disks are working much better now compared to older models). But the reallocation procedure may cause system instability if it takes too much time.
The user should not notice anything about the steps described above - just when the number of bad sectors is high enough (the threshold is reached) and then S.M.A.R.T. predicts a possible failure.
A very small scratch or mote on the disk surface can cause some bad sectors. Usually, if the number of bad sectors is low, they do not cause big problems. But if their number is constantly increasing (and the displayed health value is decreasing), these can lead to failure. It is recommended to monitor your hard disk constantly if your hard disk is not 100% perfect.
The text description may contain that the SSD is perfect but the health is relatively low. This can happen if the SSD has no errors, no signs of bad sectors (bad memory cells) or similar problems.
However, due to the wearing of the memory cells caused by write operations to the SSD, the health of the SSD is constantly decreasing. The wear-leveling feature of the SSD tries to minimise this effect - but can't be totally eliminated.
The current health of this SSD is determined by some specific S.M.A.R.T. attribute(s), for example the "#209 Remaining Drive Life" (or one or more other attributes) as mentioned by Hard Disk Sentinel. If you select that attribute on the S.M.A.R.T. page, you can check how it changed over time on the graph below the list.
If the health of the SSD is low, it is possible that the data stored in the memory cells will become damaged or lost.
Hard disks are not affected by this (wear) effect, so it is possible to find lots of hard disks with 100% health (even after years of usage). In contrast, the health of the SSDs is constantly decreasing over time.
It is recommended to periodically analyse and verify the disk status (especially if the hard disk is not perfect, the health is below 100%). Hard Disk Sentinel offers high number of tests from the Disk menu: including hardware self-tests, to analyse the functionality of the hard disk components and the entire surface. These hardware tests can be started from the Disk menu, the Information page or automatically (scheduled) on the Operations page (Professional version only).
Also the Disk menu Surface test can be used to verify the disk surface with both read and write tests to reveal and fix disk issues.