OWC Enclosures & Drive Docks: 4Kn Drive Compatibility

Created on: December 13, 2016
Last updated: May 14, 2018

Currently most OWC storage solutions do not support native 4K (4Kn) hard drives; only the OWC ThunderBay 4, OWC Mercury Elite Pro Quad, OWC Rack Pro mini-SAS, ThunderBay 4 mini (legacy product), the upcoming OWC ThunderBay 6, and OWC's Jupiter enterprise solutions support these drives. All other products require hard drives that support 512e technology (512 byte logical blocks mapped to 4096 physical blocks), or drives with native 512 byte block size. To learn more about 4Kn and 512e, including methods for identifying these drives and which systems support them, please read the information below.

As of May 2018, OWC offered four brands of 3.5 inch SATA hard drives: HGST, Toshiba, Western Digital, and Seagate. Since 2011, these manufacturers and others began to offer hard drives with a physical block size of 4096 bytes (4K for short). This is a major shift from the 512 byte physical block size used for many years prior to 2011. The main benefits are the potential for greater capacities and improved reliability, as well as some performance gains. However, many existing operating systems, applications, devices, and computers were designed to work specifically with drives that provide 512 byte block sizes.

To ease the transition to 4K native drives (4Kn for short), drive manufacturers have integrated 512 byte emulation technology (or 512e for short). This enables drives with physical block sizes of 4096 bytes to work with computers, systems, applications, and devices designed for use with drives that have 512 byte physical blocks. OS X 10.4 or later will work for Mac systems and peripherals that support 4Kn drives, and Windows Vista SP1 or later will work for PC systems and peripherals that support 4Kn drives.

These are also referred to as "Advanced Format" drives and will often carry the Advanced Format 'emulation logo' on their label. The logo looks like the ones shown below.  




4K native (4Kn) drives which do not support the 512e technology are also a type of 'Advanced Format' drive, however they should display a different logo on their label (see below).


As of December 2016 all 4K SATA drives offered by MacSales.com support 512e, based on the specifications and/or product manuals on the manufacturer web sites at that time.

Do not purchase 4Kn drives unless you are sure your system — including any OWC hardware — supports this format.