There’s nothing actually wrong conceptually with SMR drives in RAID. The write order used by the RAID system simply needs to be appropriate for such a drive. The early SMR drives tried to hide what they were, and simply didn’t have sufficient cache area for non-sequential workloads in any volume. This is frankly a QA failure on the part of WD, Seagate, and Toshiba. They assumed that most RAID systems were for bulk storage, SMR drives are great for getting more bulk storage in a smaller space, why wouldn’t that be awesome? They obviously never did more than cursory testing. The fact that some of these drive-managed units also didn’t actually succeed at hiding what they were and would return strange errors under certain circumstances probably didn’t help things. Basically alpha technology pushed out in secret and it failed to perform. There’s been at least one lawsuit about it along false advertising lines.
However, over the last year, there has been a lot of work done on updating filesystems, raid controllers, kernels, and everything else to handle zoned storage, I’ve seen firmware updates going past for a lot of hardware RAID controllers, along with updates for mdraid, BTRFS, ZFS, etc. So as long as you get drives that are either host-aware or host-managed and have the very latest software for your setup they should no longer crash and burn on a RAID rebuild. I’d probably wait another year for all the bugs to work their way out of the system before trying it on purpose, but if you have non-critical systems to play with, well, the SMR drives are rather a lot cheaper… I got a few for one of my server chassis because they can cram 5TB of storage into a 2.5” drive that fits in the bay for only $120. LMP From: Julien Roy <jul...@jroy.ca> Sent: Thursday, March 3, 2022 2:55 PM To: Gentoo User <gentoo-user@lists.gentoo.org> Subject: Re: [gentoo-user] planning a new machine : comments welcome Even of WD's official page for WD Reds, they are still advertised for RAID: https://www.westerndigital.com/products/internal-drives/wd-red-sata-hdd#WD20EFAX For instance : ● Reliability: The always-on environment of a NAS or RAID is a hot one, and desktop drives aren’t typically designed and tested under those conditions like WD Red™ is. ● Error recovery controls: WD Red™ NAS hard drives are specifically designed with RAID error recovery control to help reduce failures within the NAS system. Or: Designed with SMR technology for workloads associated with personal and home office, such as storing, archiving and sharing, in RAID-optimized NAS systems with up to 8 bays. This isn't just NewEgg or Amazon puting outdated information on the product page, it is WD still advertising today that the SMR WD Reds are appropriate for RAIDs, while they are, in fact, not. Regarding the blogpost: I don't think a blogpost is appropriate for a company to correct information about deffective product, when the advertising for the said product remains uncorrected. Nevertheless, even in their blogpost, they aren't being entirely honest, since they still claim that WD Reds are appropriate for RAIDs: "In a RAID rebuild scenario using a typical Synology or QNAP (non-ZFS) platform, WD Red DMSMR drives perform as well as CMR drives or show slightly longer RAID rebuild times, depending on the condition of the drive and extent of rebuild required." They double down on this further in the blogpost. From some quick research, this is only true in a RAD1 array. In any other type of array, it is sometimes impossible to expand or rebuild the array with SMR drives. See: https://raid.wiki.kernel.org/index.php/Timeout_Mismatch Julien Mar 3, 2022, 16:27 by markkne...@gmail.com<mailto:markkne...@gmail.com>: On Thu, Mar 3, 2022 at 2:11 PM Julien Roy <jul...@jroy.ca<mailto:jul...@jroy.ca>> wrote: The WD Reds are still marketted as RAID compatible to this day, despite the fact that they are SMRs. Julien 18 months ago WD put out this statement: https://blog.westerndigital.com/wd-red-nas-drives/ If by 'marketed' you mean Amazon or Newegg or some other seller is telling people that the SMR is a good RAID solution I wouldn't say that's on WD but rather the vendor. Just my 2 cents, Mark
