There is a new type of technology out there that allows hard drive manufacturers to increase the capacity of hard drives.  It is called shingled magnetic recording.  These hard drives should be avoided at all costs, at least for several years. Before buying a hard drive, look up the model number on the manufacturer’s website. Make sure the specs do not mention shingled magnetic recording or SMR. These types of hard drives are now being found in capacities as low as 2 TB.

First problem: Because of the technology is new, failure rates are high.

Second problem: SMR drives have a small traditional hard drive space and a shingled majority space.  All your data is first written to the traditional spot.  Then, when there is an idle period, the data is transferred to the shingled spot. But if the traditional space fills up before there is an idle period, it has to stop everything it is doing and clear the traditional space.  This can take a long time. This means that any action that requires a large amount of data written, such as RAID rebuilds, will either fail or take significantly longer. How much longer? Some people report that a RAID rebuild that should take 1 day actually took 8 days, after they figured out how to stop the RAID system from thinking the drive was bad.

Third problem: SMR drives cannot be defragmented to improve performance. This is because the hard drive, not the operating system, decides where the store the data on the shingled part. This also means these drives would be terrible as a boot drive.

When the technology matures and when hardware and operating system makers properly implement compatibility for SMR drives, they should be sufficient for bulk storage with infrequent writes. This means they will not be good for boot drives or DVR’s like TiVo.