Western Digital 2TB-6TB WD Red NAS are using SMR, an issue with NAS RAID? (Updated)

And that's a problem with RAID NAS setups. Blocks and Files report that users are experiencing problems adding the latest WD Red NAS drives to RAID arrays, they suspected it is because they are actually shingled magnetic recording drives submarined into the channel.

Alan Brown, a network manager at UCL Mullard Space Science Laboratory, the UK’s largest university-based space research group, told Blocks and Files about his problems adding a new WD Red NAS drive to a RAID array at his home. Although it was sold as a RAID drive, the device “keep getting kicked out of RAID arrays due to errors during resilvering,” he said. Similar issues have been reported at the Synology forums.

Shingled media recording (SMR) disk drives take advantage of disk write tracks being wider than read tracks to partially overlap write tracks and so enable more tracks to be written to a disk platter. This means more data can be stored on a shingled disk than an ordinary drive. However, SMR drives are not intended for random write IO use cases because the write performance is much slower than with a non-SMR drive. Therefore they are not recommended for NAS use cases featuring significant random write workloads. The guys brought all these points to Western Digital’s attention and a spokesperson told us:

“All our WD Red drives are designed meet or exceed the performance requirements and specifications for common small business/home NAS workloads. We work closely with major NAS providers to ensure WD Red HDDs (and SSDs) at all capacities have broad compatibility with host systems.

“Currently, Western Digital’s WD Red 2TB-6TB drives are device-managed SMR (DMSMR). WD Red 8TB-14TB drives are CMR-based.

“You are correct that we do not specify recording technology in our WD Red HDD documentation.

“We strive to make the experience for our NAS customers seamless, and recording technology typically does not impact small business/home NAS-based use cases. In device-managed SMR HDDs, the drive does its internal data management during idle times. In a typical small business/home NAS environment, workloads tend to be bursty in nature, leaving sufficient idle time for garbage collection and other maintenance operations.

“In our testing of WD Red drives, we have not found RAID rebuild issues due to SMR technology.

“We would be happy to work with customers on experiences they may have, but would need further, detailed information for each individual situation.”

If all that is correct then there is no solution to the problem at hand, other than returning the HDD and replace it with another one. The Western Digital markets WD Red series has been marketed as NAS HDD, and as it seems now, certain revisions will have RAID issues. WD seriously goofed up here in their communication. of course for non-RAID setups, this is not an issue. Remember, the latest WD Red 2TB-6TB WD NAS ready drives seem to use shingled magnetic recording.

Updated April 22nd, 2020 - WD posted on their blog a word on two on the issue, pretty much defending their choice and pointing Users to WD Red Pro or WD Gold for RAID.

WD - Recently, there has been discussion regarding the recording technology used in some of our WD Red hard disk drives (HDDs). We regret any misunderstanding and want to take a few minutes to discuss the drives and provide some additional information.

WD Red HDDs are ideal for home and small businesses using NAS systems. They are great for sharing and backing up files using one to eight drive bays and for a workload rate of 180 TB a year. We’ve rigorously tested this type of use and have been validated by the major NAS providers.

We typically specify the designed-for use cases and performance parameters and don’t always talk about what’s under the hood. One of those innovations is Shingled Magnetic Recording (SMR) technology.

SMR is tested and proven technology that enables us to keep up with the growing volume of data for personal and business use. We are continuously innovating to advance it. SMR technology is implemented in different ways – drive-managed SMR (DMSMR), on the device itself, as in the case of our lower capacity (2TB – 6TB) WD Red HDDs, and host-managed SMR, which is used in high-capacity data center applications. Each implementation serves a different use case, ranging from personal computing to some of the largest data centers in the world.

DMSMR is designed to manage intelligent data placement within the drive, rather than relying on the host, thus enabling a seamless integration for end users. The data intensity of typical small business/home NAS workloads is intermittent, leaving sufficient idle time for DMSMR drives to perform background data management tasks as needed and continue an optimal performance experience for users.

WD Red HDDs have for many years reliably powered home and small business NAS systems around the world and have been consistently validated by major NAS manufacturers. Having built this reputation, we understand that, at times, our drives may be used in system workloads far exceeding their intended uses. Additionally, some of you have recently shared that in certain, more data intensive, continuous read/write use cases, the WD Red HDD-powered NAS systems are not performing as you would expect.

If you are encountering performance that is not what you expected, please consider our products designed for intensive workloads. These may include our WD Red Pro or WD Gold drives, or perhaps an Ultrastar drive. Our customer care team is ready to help and can also determine which product might be best for you.