Last week, news broke that Western Digital, Samsung, and Toshiba were all shipping hard drives that used Shingled Magnetic Recording (SMR) technology in certain product lines without informing customers they were doing so. This has become a problem for some WD Red customers who deployed the drives in a NAS or desktop RAID array — after a drive failure, a RAID controller may refuse to repair the array if an SMR drive is swapped in to replace a CMR design. Readers have reported similar issues since we published our last article.
The reason SMR is considered inferior to CMR for many applications is because SMR drives place tracks more closely together than their CMR counterparts. This does not impact read speed, but it has a significant impact on write. In order to write to one track, the HDD has to perform an operation equivalent to a program/erase cycle on an SSD. This takes a significantly longer period of time than a standard HDD (which isn’t exactly fast) and it hits the performance of these drives hard in write-heavy workloads.
Western Digital’s blog post is a long article extolling the benefits of SMR and failing to mention that customers are factually having RAID failures when they replace a CMR drive with an SMR drive Western Digital sold them as an acceptable replacement for this purpose. It’s basically worthless, save for giving you a list of drives to avoid if you do not want to deal with this headache.
To be clear, SMR drives factually work in modern systems, and they work just fine if you don’t plan to write much data. A single external backup drive being SMR versus CMR is no big deal, but that’s not the only place WD sells them.
Selling an SMR drive in the WD Black line is an insult to the product. When Western Digital created its initial color-based branding, WD Black hard drives were supposed to sit at the top of the stack, surpassed only by the Velociraptor family. Putting an SMR product in that stack is Western Digital’s way of quietly acknowledging that hard drive performance is a dead letter category since SSDs became widespread. The WD10SPX is the only offender in this category, the WD5000PLX, 3200LPLX, and 2500LPLX are apparently unaffected.
I’m not opposed to SMR drives. They boost capacity, can reduce power consumption, and offer a larger capacity in the same number of platters. The performance tradeoff is worth it in certain markets and irrelevant in others. No argument. But these parts didn’t just magically appear in WD’s product lines in the first place. A decision was made to swap one technology for another, and a decision was made not to tell consumers about the change. At least in the case of the WD Red family, there’s evidence those changes weren’t evaluated as closely as they should have been.
We are glad to see Western Digital has chosen to be honest about its product shipments. It needs to continue to update these charts as it introduces new products to let customers know what they’ll be buying if they choose an SMR drive. Using SMR instead of CMR is fine. Not telling people about the difference isn’t.
Last week, I said I would not recommend a hard drive from any vendor until companies were more transparent about their product mixes. So long as Western Digital continues to inform customers where SMR drives are and are not being used, I have no problem recommending products from the company.
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