I brought a 2TB WD black drive. Installed it on an external USB/eSATA enclosure, and connected to the pi (via USB obviously). Partitioned it with gdisk with GPT (with protective MBR) and created one big partition of 1.8 TB, formatted in ext4. Rebooted to automount. Automount OK. The disk is empty, and the enclosure LED keeps blinking on each second. I tried writing via SAMBA from my laptop and worked OK, played the file on XBMC and everything was OK. But I am still worried about the disk activity since it will be powered 24x7 and because I had a 640GB drive (NTFS formatted) until now and the disk activity light wasn't blinking each second as it does now. I tried to use iotop to confirm wich process is writing/reading to/from the disk, but it says it cannot run on the raspbmc kernel.
I have done some testing since my first posting:
I hooked the disk to a desktop computer via USB, running slax (usb-bootable slackware-based distro). Has the same behavior, activity LED blinks each second.
I also booted up a fresh install of raspbian, hooked the drive to the pi, and is the same as raspbmc.
Finally installed iotop on raspbian and could pin point the issue: the process jbd2/sda1-8 is the cause. Apparently is related to journaling.
Found some posts about the issue:
but no clear fix.
I think that this may be related to the fact that all distros I have tested until now are booted from USB/removable storage. May be there is some journaling config on the raspbian/slax to write more often, given that are prepared to run on removable devices. But it sounds crazy because removing the boot devices while the system is running will probably turn the system too unstable to work (if it even manages to keep running).
NEW UPDATE: Disabled ext4 journaling on the filesystem (whooping 200 gb!) using
tune2fs -O ^has_journal /dev/sda1
Activity led still blinks each second! iotop shows ext4lazyinit but not as frequent as the LED blinks. jbd2 still runs but for the SD card only. The last stop is USB sniffing, I will try it as soon as I have some spare time.