NAS: The downfall of desktop-class harddrives

As the DS107+ is a single-bay NAS there is no option for raid. To have proper redundancy you need at least a 4-bay (preferably 5-bay for appropriate speed) NAS-device – which costs a small fortune. With a single-bay NAS you are also caught between a rock and a hard place:

Today’s hard drives have a built-in capability called “sector remapping” which will remap (or repair) the defective sector with a backup supply of sectors. This process is seamless to the user and it doesn’t require user intervention. However, if there are several defective sectors, the hard disk can time out while attempting to remap multiple defective sectors, which can result in the computing device that the hard disk is failing to respond correctly, or it can lead to other difficulties, such as communicating or retrieving data from the hard disk. And this was exactly what happened on my NAS – nothing wrong with the drive or the NAS.

Any desktop-class hard-drive will only remap bad sectors as they are detected. This can cause massive delays (in the extend of 10 seconds to several minutes per sector) when remapping sectors. Using Enterprise-Class disks can usually avoid this error, as most Enterprise-Class disks are designed to remap a defective sector under ten seconds (instead of several minutes with Desktop-Class).

Using Enterprise-Class disks in a single-disk system may result in loss of data with regards to sector remapping. And therefore It is not recommended to use Enterprise-Class disks for a Single-disk system/application.

Originally I had initialised my desktop-class harddrive (a 1TB WD Caviar @ 3Gb/sec) through OS X and was still amazed how quickly the drive was initialised – WRONG.

After some time I realised that the drive started to “flake” out, as it was busy remapping bad-sectors (which is normal in any drive, and there is virtually no drive which does not have bad sectors).

The easiest way to work around this (and it also applies to enterprise class devices), is to “proactively” reducing or eliminating the possibility of any computing device from encountering defective sectors on hard disks. How it works is by filling every sector with data, thus forcing the HDD to use every single sector. By using every single sector, it requires that all the bad sectors to be remapped immediately, instead of waiting to attempt to remap the sectors during system operation.

BE AWARE: The method below takes several hours!!! In my case it “zeros-out” the harddrive at 30MB/sec which will take about 10 hours until the drive has been initialised.

  1. You can use any security software to do this. I chose “Darik’s Nuke and Boot (“DBAN”)“. I also chose the beta-version, as it supports external USB and firewire drives.DBAN) is a self-contained boot disk that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.
  2. Burn the image to CD and boot from it.
  3. DBAN will boot up to a blue screen, with a series of options using the Function Keys, press “ENTER” to continue
  4. CAUTION: Ensure that you select the correct drive – once you press F10, your selected drive is toast!!!
  5. Select “quick wipe” as the erase method and select the appropriate hard-drive
  6. Press “F10” to wipe the harddrive (this is the point of no return!!!
  7. several hours later: Your drive should now be ready to be installed in your NAS.

Update (screw Ubuntu): Well, Ubuntu flaked out on me and crashed after erasing 100gigs of data. If you are lucky enough to have OS X (duh – how could I forget about this) – you can use the DiskUtility, erase the partition and then under security options select how you want to erase the drive (at least OS X will do it in 9 hours):

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