SMR vs CMR Drives: Understanding the Differences

In recent years, buying hard drives has become more complex. The introduction of Shingled Magnetic Recording (SMR) drives has added a new dimension to the market. But what exactly are SMR drives? And how do they differ from Conventional Magnetic Recording (CMR) drives? In this article, we will explore the differences between SMR and CMR drives and how to identify them.

What Are SMR and CMR Drives?

All hard drives are not created equal. While most performance metrics are not of concern to the average user, the storage method used in a drive can have a significant impact on user experience.

Historically, CMR drives have been the default storage method. These drives write data to concentric circular tracks on the platters without any overlaps. This method allows for increased capacity by either increasing the number of platters or multiplying the write density.

On the other hand, SMR drives use a different technique. They write data by partially overlapping existing tracks where data is already present. This stacking of tracks allows for increased data capacity without adding more platters or increasing data density. SMR drives can be thought of as the “shingles” on a roof, hence the name.

Is SMR Drive Inferior to CMR?

In terms of performance, SMR drives are generally inferior to CMR drives. Here are a couple of reasons why:

Speed

SMR drives are slower, especially when it comes to write speeds. Unlike CMR drives, which can write data directly, SMR drives need to temporarily copy the data to a specialized cache before reorganizing it into the shingled regions of the tracks. This process can cause bottlenecks and slowdowns when large amounts of data need to be written.

Data Corruption

The chances of data corruption are higher in SMR drives. The constant modification, reorganization, and deletion of pre-existing data on the tracks make them more prone to corruption. Sudden power outages or interruptions during this process can put data at risk. SMR drives also take longer to integrate into RAID arrays, which can put other CMR drives at risk.

Applications for SMR Drives

While SMR drives may have some limitations, they do have their advantages in certain applications:

Cheap

SMR drives are cheaper compared to CMR drives. The reduced number of platters in SMR drives leads to lower production costs and less material usage. This makes them suitable for archiving purposes where frequent rewrites are not required.

Energy Efficient

SMR drives are more energy-efficient than CMR drives. The reduced number of platters and heads required for data movement results in lower power consumption. This energy efficiency becomes even more significant when SMR drives are used on a larger scale, as demonstrated by Dropbox's energy savings experiments.

How to Identify Between SMR and CMR Drives

Identifying whether a hard drive is SMR or CMR can be challenging, as they are not always clearly labeled or mentioned in the specifications. However, some manufacturers have started listing which drives use SMR and CMR. For example:

• Seagate has a clear list of their drives that implement SMR and CMR.
• Western Digital has made a blog post revealing the models that use CMR and SMR.
• Toshiba has an official list of consumer drives that use SMR and CMR.

If a manufacturer does not provide this information, you can try the following methods to identify the drive:

• Check the drive's cache/buffer size. SMR drives usually have a larger cache compared to CMR drives.
• Check for TRIM support. Newer SMR drives may have TRIM support, which is not required for CMR drives. You can use applications like CrystalDiskInfo to check for TRIM support.

Remember, it's always best to do your research and consult manufacturer resources to ensure accurate identification.

In Conclusion

SMR drives and CMR drives have their own strengths and weaknesses. While SMR drives may be slower and more prone to data corruption, they are cheaper and more energy-efficient. Understanding the differences between these two technologies and how to identify them can help you make informed decisions when purchasing hard drives.

And if you're looking for recommendations, check out our article on the top 5 external drives for your PS5.