hdd led flashes almost always every 2-3 seconds

Hello,

If the computer you are using is a laptop, i guess you may be a victim of the following issue :
http://ubuntudemon.wordpress.com/2007/10/26/laptop-hardrive-killer-bug/

I hope this help.

laptop mode is off.
i think there is a program newly installed writes or reads something. how can i catch what program is it?

Some people who didn’t enable laptop-mode can also be affected because your harddrive’s firmware or your BIOS might also tell your harddrive to do aggressive power management.

how can i know whether it is parking head or only reading?
it does not sound like parking head.

There is a variable which store the number of time your head has been parked, this is called Load_Cycle_Count.
To view your Load_Cycle_Count in a terminal :

$sudo apt-get install smartmontools
This will intall the tool we need.

$sudo smartctl -a /dev/sda | grep Load_Cycle_Count
This will come with a line with a number at the end. Jot down the number and check again in 24h or 2h. If this figures is increasing too fast, you should apply the ugly fix as mention in the link above.

smartctl -a /dev/hda | grep Load_Cycle_Count
and
smartctl -a /dev/hdc | grep Load_Cycle_Count
say nothing.
i looked at them without grep, there is no "Load_Cycle_Count".

and in many lines is "pre-fail" or "old age". is that mean that it is has got old?

that is of hdc:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate 0x000f 112 090 006 Pre-fail Always - 0
  3 Spin_Up_Time 0x0003 090 089 000 Pre-fail Always - 0
  4 Start_Stop_Count 0x0032 099 099 020 Old_age Always - 1607
  5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 0
  7 Seek_Error_Rate 0x000f 081 060 030 Pre-fail Always - 161988591
  9 Power_On_Hours 0x0032 097 097 000 Old_age Always - 3176
 10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0
 12 Power_Cycle_Count 0x0032 098 098 020 Old_age Always - 2783
187 Unknown_Attribute 0x0032 100 100 000 Old_age Always - 0
189 Unknown_Attribute 0x003a 100 100 000 Old_age Always - 0
190 Temperature_Celsius 0x0022 067 053 045 Old_age Always - 555745313
194 Temperature_Celsius 0x0022 033 047 000 Old_age Always - 33 (Lifetime Min/Max 0/16)
195 Hardware_ECC_Recovered 0x001a 072 057 000 Old_age Always - 27095
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0010 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x003e 200 199 000 Old_age Always - 3
200 Multi_Zone_Error_Rate 0x0000 100 253 000 Old_age Offline - 0
202 TA_Increase_Count 0x0032 100 253 000 Old_age Always - 0

does that mean that hdc is in bad condition?

I had a similar issue on my dell inspiron 6400 and this was the solution. You may have a different issue. I can't answer your question. Anybody else ?

after that i had reinstalled ubuntu. and that stopped.
now it has started again. may be it is because free space on partition has been left 0 bytes. this happened 1-2 days ago. also after that php has made errors writing to files and nautilus bookmarks disappeared and strange sql file appeared on / . in my this installation all main directories are in only one / partition, all other partitions are only in /mnt/ . and may be it is because i have just changed cd recorder to other...
also similar flashing was happening in windows sometime, it was also strange.

hello. now i have changed dvd drive back and it does not flash now.

hello. now it changed by itself and cd recorder does cannot open disks now, maybe because ide cable and hdd led flashes that way now again or maybe previous time i wrote i did not notice led flashes because was daytime.

now it does not flash every 2-3 seconds , now i have new cd, dvd device and now i have upgraded to ubuntu 9.04.

i said: "how can i catch what program is it?" - now i know that with iotop.
now i use ubuntu 9.10 .
and now, maybe just today, it again started to flash. and i have known out that kjournald2 process writes every few seconds and there are bug reports about it.
searched for kjournald2 with google and found from its 1st result page:
http://www.linuxquestions.org/questions/mandriva-30/kjournald2-active-every-two-seconds-773791/
http://www.linuxquestions.org/questions/linux-kernel-70/kernel-oops-kjournald2-commit-issue-793903/
https://bugs.launchpad.net/ubuntu/+bug/442443
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/483569
http://forums.linuxmint.com/viewtopic.php?f=47&t=40872&start=0
https://bbs.archlinux.org/viewtopic.php?id=84953 (here is link to https://qa.mandriva.com/show_bug.cgi?id=56245 )