Can you reproduce the situation when using
Code:
hdparm --direct -t device
You should
always use the
--direct option when accessing devices, because it avoids the page cache.
You can also see if
Code:
sudo bash -c 'sync ; echo 3 >/proc/sys/vm/drop_caches ; sync'
affects your timings. (It should not affect
--direct timings though, because that should completely bypass the caches anyway.) This command is safe to run at any time; it just flushes all caches and unwritten changes to disk, then clears the caches. It will never discard unwritten changes.
You should make sure you have
smartmontools installed, and check the SMART data:
Running a self-test (
-t short or
-t long ), waiting (without rebooting -- otherwise the disk can be used normally) usually quite some time (you can use
smartctl -a device to see the progress), and then an offline test (
-t offline ) to update all offline attributes, and rerunning
smartctl -a device will tell you more about the physical state of your storage device. Uh, assuming it does have SMART support.
Finally, you could install and run
iotop before testing, to really see if you have background processes (like indexing or other housekeeping stuff, that most Linux distributions do use) accessing storage, just before running
hdparm --direct -t. (Personally, I find
hdparm -T to be quite worthless in practice.)