4Kn Hard Drives & Backwards RAID Compatibility | TechMikeNY



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Compatibility Pain Points: 4Kn Hard Drives and Backwards Compatibility with RAID Controllers


With the advances in hard drive technology, manufacturers have started taking advantage of higher hard drive density so that you, the consumer, can get the most bang for the buck.  If you have ever heard the term “4Kn” in a hard drive’s specs – this is a relatively recent development in hard drive architecture that allows for more of the disk’s volume to be used.

This post will give some background on 4Kn sectored drives and some compatibility issues with Dell and HP RAID controllers that are not compatible with 4Kn hard drives. 

But first, exactly what is a 4Kn hard drive?   

Hard drives are divided into partitions or sectors, which is the minimum data storage unit in a drive.  Hard drives, for a very long time, have existed with 512-byte sectors.  Each of the sectors is divided by spaces that check the data for errors (Error Correcting Code, or “ECC”), among other things.   The problem with these spaces is they take up some of the volume on the drive that would preferably be used for your data.  If you have ever noticed the phenomena where your drive's size is showing less volume available than is stated (“Why is my brand new 600GB drive only showing 550GB available?!”), this is partly the reason. 

4Kn hard drives (4K = 4096 bytes; n = native) utilize much larger drive sectors, allowing the spaces to be less frequent.  The benefit of fewer spaces is it allows for more of the drive’s volume to be used for your data.  In fact, compared to the traditional sector size of 512-byte drives, which use approximately 92% of their volume, 4Kn drives use up to 97%.  

 NOTE: You will find that most drives that utilize the 4Kn format are massive drives data-wise, usually in the 3TB volume and above.

The 4Kn logo.  If you see this image on your drive, it is a 4Kn-formatted drive.

Hold on, though. There is also a 512e formatted drive – which is ‘Advanced Format’ as well

Added into the family of Advanced Format (AF) drives, you have 512e (e = emulation).  Because the sector size impacts the read & write protocols of a drive, a middle-ground solution was developed to allow the transition between 512n and 4Kn drives.  A 512e formatted drive has 4K-bytes per physical sector but maintains 512-bytes per logical sector.  Put simply, the logical sector “tricks,” or emulates, the system into thinking it is a 512-byte formatted drive, while the physical sector remains 4K.  512e formatted drives allow for the installation of Advanced Format drives into devices running an OS that does not support 4Kn sectored drives. 

This Advanced Format logo on a drive means the drive’s physical sector is 4K-byte.

 THE MORE YOU KNOW: Don’t confuse the terminology used to describe a ‘4Kn’ drive versus a drive advertised as ‘10K’ or ‘15K.’  4Kn is the drive’s sector size; 10K or 15K refers to the RPM’s (Revolutions Per Minute) of a traditional platter drive – how fast it can read & write.  

The bottom line: what is – or isn’t – compatible with Advanced Format Drives

Since 4Kn drives have been around for a couple of years now, many newer devices that run end-user-oriented OS’s, such as Windows 10, will support AF formatted drives – although if you are upgrading the hard drive on your system, you should always check the manual to confirm.  However, servers frequently have multiple hard drives configured in RAID, so a compatibility consideration needs to be made in regards to the server’s RAID controller when installing Advanced Format Drives.

Since TechMikeNY is a primarily a refurbished server house, here are some general compatibility rules to keep in mind in regards to Dell and HP servers:

  • 4Kn formatted drives will not work with PERC’s (PowerEdge RAID Controller) in 12th Generation (and prior) Dell servers.
  • 4Kn formatted drives will not work with Smart Array RAID controllers in 8th Generation (and prior) HPE servers.
  • 512e formatted drives will work in RAID with these HP and Dell servers.
  • 4Kn drives – SAS only – could work in these generation servers in a non-RAID/pass-through configuration. Though the OS running on the server would need to support 4Kn formatted drives as well.  Due to the variables involved, we do not recommend it. 

A reminder: you always want to match drives’ specs in RAID as much as possible.  We have fielded many support queries from customers who added their own drives to spare bays on their server, to find that mismatched drives caused all sorts of issues with the RAID configuration. 

At first blush, SAS and SATA ports look very similar – they both use 15 pin power and 7 pin data connections. However, the SAS port has a bar that prevents a SATA cable from plugging into it. SAS is a more reliable and faster data connection.

Lastly, never hesitate to reach out to us at info@techmikeny.com – one of our techs will respond promptly and can even provide a consultation on the phone.  Building servers is what we do at TechMikeNY, so we are happy to help!


  • Hi AJ,

    To use 4Kn drives in systems that run Server 2012 or Windows 8, you would need to make sure that the hardware is capable of supporting 4K drives.

    If the hardware supports it, then when the drive is initialized, you will be able to use the 97% of the drive.

  • how to make full use of 4kn drives of the 97% in windows server 2012 or windows 8.1?

  • Thanks. As of 2022 using PowerEdge 13G servers + electing to use 512-byte drives seems to offer best compatibility across the board, and compatibility is more valuable to me at the moment.

    Rubber Chicken

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