What use are SMR HDD's

[RobertP]

Shingled Magnetic Recording drives have a bad name, and rightly so if you need to write continuously for more than a couple of minutes, because the firmware just can't cope and frequently grinds to a halt for a few seconds. As someone who always buys NAS HDD's for their longevity and durability (Toshiba N300's are my poison), and uses RAID as a matter of course, that simply isn't acceptable.

However, I came across four unwanted Seagate Barracuda 2Tb HDD's in a cupboard and thought it would be fun to see how they ran as a four spindle RAID 0 array; after all, these are 7200rpm drives with a 256MB buffer. So, duly attached to an Adaptec 7805, I gave them a whirl. And the results were surprising.

On a sustained I Tb video file transfer (average size 500 MB), settling down at 380-390 MB/sec after the initial rush; by way of comparison my Toshiba's run at 860-880 MB/sec. But reversing the copy was illuminating. the Seagate's read the data back at 830-840 MB/sec, which is pretty much as fast as the Toshiba's write, 840-850 MB/sec.

So assuming you have adequate backups, this would offer a significantly cheaper way of fulfilling a write once, read many, requirement. for non critical data.

I also repeated this test over a 10Gbs network, and the Seagates ran at 770 MB/sec read / 330 MB/sec write, while the Toshiba's posted 790-810 MB/sec read/ 750-780 MB/sec write.

Lastly, I tested the Seagates copying the same data to a Seagate Firecuda 530 SSD 4Tb, and 830-840 MB/sec read seems to be read their limit. Needs more work, but SMR HDD's may actually have a use after all.

 

[ChatGPT]

Thank you for sharing your experience and findings with using Shingled Magnetic Recording (SMR) drives in a RAID 0 array. It's interesting to hear that you had a positive experience with the Seagate Barracuda drives in this configuration.

Indeed, one of the drawbacks of SMR drives is their slower random write performance compared to conventional drives. The nature of the shingled recording method can cause difficulty in handling continuous writes, as you mentioned. However, for sequential read and write operations, such as your scenario with large video file transfers, SMR drives can still deliver respectable performance.

In your tests, it's impressive to see the sustained transfer speeds achieved by the Seagate drives in the RAID 0 array, even though they may not match the performance of your Toshiba NAS drives. The fact that the Seagate drives were reading back at speeds comparable to the Toshiba drives' write performance is noteworthy. This suggests that for scenarios where write frequency is less critical and read performance is more important, SMR drives could indeed find a use.

Additionally, your test over a 10Gbps network further demonstrated the capabilities of the Seagate drives. While their write speed was not as high as the Toshiba drives', the read speed remained competitive. This reinforces the idea that SMR drives can be a cost-effective solution for scenarios where read-intensive operations are the primary concern.

Lastly, your experiment with copying data to an SSD further highlighted the limitations of the SMR drives, as they reached their read speed ceiling. This emphasizes the importance of considering the specific requirements and use cases when choosing the appropriate storage solution.

Overall, your findings suggest that SMR drives, such as the Seagate Barracuda, can have a useful role in certain scenarios where write frequency is lower and sequential read performance is key. It's great to see you exploring alternative uses for the drives you had on hand and sharing your valuable insights with the community.