Choosing Between CMR and SMR Technology in Hard Drives

Which technology should I use for my hard drives? This is one of the commonly asked questions of those who want to buy a new hard drive. There are numerous options in the market.

So, in this article, we will focus on CMR and SMR technology in hard drives to find which one is better.  

What is CMR?

It is essential to understand these technologies first before giving a final verdict about the better one. CMR stands for conventional magnetic recording. It is the standard technology which has been used since the mid-2000s behind hard drives. In CMR, data is written on the magnetic tracks present side-by-side and don’t overlap. Moreover, they write operations on one track without affecting their neighbours.

What is SMR?

SMR is relatively a new contender in the market and stands for shingled magnetic recording. The word shingled in its name indicates that data tracks can be visualized like roofing shingles. However, they partially overlap each other. Consequently, as a result of this overlap, the tracks are thinner, thus giving more space for the data to fit in a given area.

Choosing Between CMR and SMR Technology in Hard Drives

Due to the wide range of options in the market, it becomes difficult for the users to choose the best technology for their hard drives. Therefore, we will explain the main differences between SMR and CMR to find which one is better.

As we have already explained in the introduction of the CMR and SMR, in CMR data tracks, don’t overlap, but that is not the case with SMR. In SMR data tracks overlap; consequently, this overlapping can complicate drive operations for writing data to the desk. As a result of which it will take additional time in SMR hard drives. On the other hand, CMR technology can use this idle time to spool those writes out to the SMR area. However, CMR has a limited capacity so that the extra write operations can be exhausted.

To understand their main differences, let’s have a look at the results of the RAIDZ resilver test. SMR drive is a NAS type drive which is suitable for arrays of up to 8 disks. When the test drive is filled up to 60% of its capacity inserts it in its place and the resolve is retimed. The test results immediately show the slow performance of SMR in contrast to CMR. The only benefit SMR has here is that after the test is done, it shows no error? However, still, its performance and speed are unacceptable.

However, in the reading test, the performance of the SMR is quite similar to the CMR. Moreover, in the write test, the results are not much different, and both show the same performance. However, the result of OCMark8 shows that SMR is better than CMR due to its large cache.

Final Words

When it comes to which one is better, both CMR and SMR have their positives and negatives. Therefore, you can choose the one that matches perfectly with your requirements and is most suitable for you. However, one thing is for sure, and that is SMR poor performance.