resolution: test every disk even if its state is NEW

Some time ago, I bought six samsung 1TB drives (P/N HD103UJ), and 3 of them has been damaged (they were pretty new, and I bought them directly from distributor!)!. Two of them has read-write errors (called bad sectors ) and one does not spin up (it has S.M.A.R.T error just at system boot). Why I chose Samsung? Because this was the only one which produced 1TB with 3 plates (6 heads). Now, because I do not trust Samsung at all I bought just a newness Seagate 1TB (P/N ST31000333AS) (same 6 heads). Samsung was a trauma for me, I wonder if Seagate has same problems. I tested this two drives, and just at start I found sth strange. One of disk does not start in one of SATA ports (another disk worked fine (I swapped them). Anyway after booting up the system, I started testing:

# smartctl -A /dev/sdf |grep On
9 Power_On_Hours 0×0032 100 100 000 Old_age Always - 0
# smartctl -A /dev/sdg |grep On
9 Power_On_Hours 0×0032 100 100 000 Old_age Always - 3

Why one of disks has 3 working hours and one has 0? Maybe because they were tested by support?

now is a time for whole surface test:

# badblocks -s -v /dev/sdf
Checking blocks 0 to 976762583
Checking for bad blocks (read-only test): done
Pass completed, 0 bad blocks found.

# badblocks -s -v /dev/sdg
Checking blocks 0 to 976762583
Checking for bad blocks (read-only test): done
Pass completed, 0 bad blocks found.

now - I am little bit more sure and I can use it

so maybe some performance test? because I do not have enought time to use bonnie++ I use a simple dd.
read:

# dd if=/dev/sdf of=/dev/null bs=1M count=8000
8000+0 records in
8000+0 records out
8388608000 bytes (8.4 GB) copied, 72.6436 s, 115 MB/s

# dd if=/dev/sdg of=/dev/null bs=1M count=8000
8000+0 records in
8000+0 records out
8388608000 bytes (8.4 GB) copied, 69.6747 s, 120 MB/s

write:

# dd if=/dev/zero of=/dev/sdg bs=1M count=8000
8000+0 records in
8000+0 records out
8388608000 bytes (8.4 GB) copied, 70.9014 s, 118 MB/s

# dd if=/dev/zero of=/dev/sdf bs=1M count=8000
8000+0 records in
8000+0 records out
8388608000 bytes (8.4 GB) copied, 71.8908 s, 117 MB/s

nice