HDD surface scan

[Marka01]

Hi to all. I'm new to this program and I would like to ask some questions:

1) when I want to scan hdd surface for bad sectors which option should I choose: verify, read (what are the differences between those two?) ? What does it do if I choose erase option ?

2) what does those colors mean (from light gray to red) ?

3) where can I find answers about common s.m.a.r.t errors so that I won't ask here too much and save your time and patience    (I'm working in IT now and need to check HDD everyday so your answers would really help a lot )  thanks for the answers.

p.s. can you give me some links of FAQ or something ? Maybe I'll find these answers there

[Doomer]

1.
Verify option reads sectors into drive's internal cache w/o sending data through the interface. If drive cannot read particular sector then drive will return an error for this sector
Read option reads sectors from the drive to your PC. This options is preferable for testing because it also includes testing of interface cable
Erase option writes selected sectors with special pattern. This options is destructive for data in erased sectors
2.
Colors mean differences in time frames which were spend while reading or writing blocks of sectors. The legend shows correspondence between colors and time frames (like 10 milliseconds, 50 milliseconds etc.)
3.
you probably can google it

[fzabkar]

3) where can I find answers about common s.m.a.r.t errors ...

I like this reference:
http://en.wikipedia.org/wiki/S.M.A.R.T.

[Marka01]

1.
Verify option reads sectors into drive's internal cache w/o sending data through the interface. If drive cannot read particular sector then drive will return an error for this sector
Read option reads sectors from the drive to your PC. This options is preferable for testing because it also includes testing of interface cable
Erase option writes selected sectors with special pattern. This options is destructive for data in erased sectors

what does "w/o" mean ? so overrall it's better to use READ option?  And I don't understand 1 more thing..how are you going to know that interface cable is bad if a program shows only bad sectors of HDD in summary ?  Btw read and verify option showed me the same result of bad sectors on 1 HDD

[Doomer]

w/o means "with out"

in UDMA mode every portion of data which was read by drive and about to be send through interface cable, protected by CRC with known algorithm
So drive calculates CRC for a data chunk then sends this packet (data+CRC)  to host
Host receives it and calculates CRC again and compares it with CRC which was calculated by drive
if CRC don't match - data integrity on the way to host was some how breached
That mostly means cable is bad
In this situation host sends signal to a drive to re-send data. Drive re-sends the packet and usually marks such an occasion in SMART attribute called "UDMA CRC Error Rate"

[Marka01]

thanks. So as I understand if check HDD surfafe through usb external adapter and I know that adapter is good so I better choose surface verify test because I dont need to check my cable as surface read test does ?

[Doomer]

correct