[jjcob]

WD Red drives. They released a new version of their WD Red drive, and the only difference they stated in the specs was that it had more cache. So I thought, great, this is their updated model with more cache, it's going to be faster.

After some time, people started to post about problems with the new WD Red drives. People had troubles restoring failed drives, I had a problem where I think the drives never stopped rewriting sectors (you could hear the hard drives clicking 24/7 even when everything was idle)

Then someone figured out that WD had secretely started selling SMR drives instead of CMR drives. The "updated" models with more cache were much cheaper disks, and they only added more cache to try and cover up the fact that the new disks suffored from catastrophic slowdowns during certain workloads (like rebuilding a NAS volume).

This was a huge controversy. But apparently selling SMR drives is profitable, so WD claims the problem is just that NAS software needs to be made compatible with SMR drives, and all is well. They are still selling SMR drives in their WD Red line.

Edit: Here's a link to one of the many forum threads where people discovered the switch: https://community.synology.com/enu/forum/1/post/127228

[fc417fc802]

> the problem is just that NAS software needs to be made compatible with SMR drives

That's half of it ... maybe? Last time I looked drives that offer host managed SMR still weren't available to regular consumers. In theory that plus a compatible filesystem would work flawlessly. In practice you can't even buy the relevant hardware.

[toast0]

> This was a huge controversy. But apparently selling SMR drives is profitable, so WD claims the problem is just that NAS software needs to be made compatible with SMR drives, and all is well. They are still selling SMR drives in their WD Red line.

Well, SMR lets you store more stuff on the same platter (more or less); fewer platters reduces costs, etc.

WD's claims about it being a software problem would be more reasonable if they were providing guidance about what the software needs to do to perform well with these drives, and probably that would involve having information about the drive available to the OS/filesystem rather than hidden.

[MortyWaves]

For future reference which WD drives are actually suitable for NAS? I remember someone saying you need to look for a specific more expensive type.

[m000]

WD Red Plus -> CMR technnology, suitable for NAS

WD Red -> SMR technology, slightly cheaper, not suitable for NAS

[kstrauser]

…but still marketed for NAS users, alas.

[m000]

I should have been more specific: not suitable for RAID NAS

RAID and NAS used to go together when drive capacities were lower. E.g. I had a 9TB NAS with RAID5 at times when 8TB drives were >$500 a pop. These days, NAS does not necessarily imply having a RAID setup. I see a new "build your SFF/RPi NAS" article every week, and it rarely involves RAID.

This is because a NAS setup with a single high-capacity drive and an online backup subscription (e.g. Backblaze) is more cost-effective and perfectly adequate for a lot of users, who have no interest in playing the sysadmin. In such a setup, you just need a drive that can withstand continuous operation, and SMR should work fine.

[kstrauser]

That's an interesting point I hadn't considered. To me, NAS implies RAID. You might be right that this is no longer true.

[kstrauser]

Frankly, I haven’t bought a single WD since. I no longer trust them as a brand, and trust is critical for this class of things.