I have a Raspberry Pi NAS setup with 2TB external hard drive (internal Hard Drive with enclosure) on it. The main drive is powered by external power adaptor that comes with the enclosure, there has been no problem so far.
I formatted my 2tb drive as so:
sda 8:0 0 1.8T 0 disk
├─sda2 8:2 0 559.2G 0 part /media/pi/Media
└─sda1 8:1 0 1.3T 0 part /media/pi/BackupI'm planning to copy some files from my other drive (1 TB Toshiba external drive) to my main drive, I originally thought the Raspberry Pi could power my external 1TB drive without the help of power adaptor, so I just plug it on my Pi usb port.
How wrong I was, it seems the Pi doesn't have enough power to carry my external drive, the 1TB start making a click sound and the power indicator on it flashing, indicate the drive is powered on --> off --> on again. I checked my main drive (the 2TB one) and I see that my Backup partition /dev/sda2 had been unmounted, it is disappear from lsblk result, there was also a window pop up telling me /dev/sda2 is not cleanly unmounted and bad superblock error blah, blah...
Panicked, I immediately pulled my external drive and my main drive out of Pi, I plugged it on my PC and ran a HD Sentinel and benchmark test. To my surprise HD Sentinel marked it as PERFECT, the benchmark also looking fine (190 MBps read/140 MBps write).
I also have recovered the damaged partition with the help of fsck, it's been several days since then and I haven't found any problem.
My question is, Can I be sure there was nothing wrong ?. I have own the drive for almost 2 years, actually this is first major problem I have with the drive.
11 Answer
Most likely the "click" sound you're hearing is just the HDD's emergency head parking mechanism triggering whenever it loses power – the same as if you unplugged a running HDD.
All HDDs are designed to automatically move the heads to a safe location when spinning down. When electric power is still available they can do this smoothly and accurately, but they also have a fully mechanical emergency parking mechanism that just flings the heads all the way towards the parking spot when power is lost. The "click" is the head assembly being stopped by a barrier.
In general, there shouldn't be any mechanical damage from this happening a few times. In fact, the purpose of this mechanism is to prevent damage to the disk platters, which are far more important and irreplaceable (see also: head crash).
(Though personally I would avoid relying on this mechanism – I kind of imagine that some things could eventually become misaligned if you make a habit of just unplugging a spinning disk every day. Better wait for it to spin down, or use 'scsi_stop' // 'hdparm -y' to stop it before pulling the plug.)
On the other hand, if the disk lost power while it was being written to, then at best you'll just have a corrupted file or two, but at worst the filesystem might have become corrupted. This is a software problem – you can use fsck to scan/repair issues in filesystem structures (note that some filesystems might have different tools, such as btrfs scrub). As for your backup, it should be re-done from the beginning.
