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Toshiba, Seagate shipping slower SMR drives without disclosure, too

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Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#81

Post by zozbot234 »

cthalupa wrote: post #62
magicalhippo wrote: post #26

Earlier quoted context omitted.

> They rebuiild (sic) for a while (1-2 hours), then throw errors and get kicked out of the set. I don't doubt it, but do you have the source for that? I read stories about people using the Seagate Archive disks in RAIDZ and it worked fine for them.

Mine completed the rebuild, but it took over 2 weeks vs. the usual 1-2 days my prior WD Red 6TBs had completed in. This has accelerated my move to enterprise 16TB drives, because I really don't want to expose myself to data loss on rebuilds taking hugely extended times.

> Mine completed the rebuild, but it took over 2 weeks vs. the usual 1-2 days

This also means you'll need a lot more HD's per RAID set to guard against multiple failures during rebuild. Which means that even the supposed data density/space advantage of SMR is moot - you'd be better off with PMR.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#82

Post by dragontamer »

uluyol wrote: post #59
dragontamer wrote: post #49

Earlier quoted context omitted.

SMR is terrible for NAS setups, particularly RAID5. Absolutely terrible. Under no circumstances should you be putting an SMR drive into your NAS.

Isn't this a question of throughput? What is the bandwidth of SMR and what workloads can't it support that PMR can? I primarily use my NAS for backups and don't care too much about how slow they are, they finish quickly enough.

SMR is like, 30MB/s write speed best-case scenario. PMR is 200MB/s write speed, easy.

We're talking about 700% difference in performance. In the case of RAID5, you have many, many physical writes per OS-level write. If you have 5-hard drives storing 100MBs, you'll need to actually write 120MBs to disk.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#83

Post by dragontamer »

otterley wrote: post #75
cthalupa wrote: post #63

Earlier quoted context omitted.

Try to do a resilver with SMR drives. I just got fucked by this change in models - I had an array full of 6TB WD Reds, had one fail, ordered a replacement. Rebuilding the RAID-Z3 took over 2 weeks. Previous replacements had taken under 2 days - usually under 1. Passing SMR drives off without saying anything, especially when that exact model had been a PMR drive prior, is incredibly anti-customer.

The model number did change. The older drive was a WD60EFRX; the newer SMR drive is a WD60EFAX. Am I mistaken?

What's going on, is that WD has for years, sold a PMR 3TB drive called "3TB WD Red".

Suddenly, without warning, the "3TB WD Red" is an SMR drive. Technically they changed the model number, but the marketing number (3 TB Red) remained the same.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#84

Post by dragontamer »

otterley wrote: post #66
cthalupa wrote: post #63

Earlier quoted context omitted.

Try to do a resilver with SMR drives. I just got fucked by this change in models - I had an array full of 6TB WD Reds, had one fail, ordered a replacement. Rebuilding the RAID-Z3 took over 2 weeks. Previous replacements had taken under 2 days - usually under 1. Passing SMR drives off without saying anything, especially when that exact model had been a PMR drive prior, is incredibly anti-customer.

I think the real answer here is to demand that disk manufacturers publish performance specifications. This leaves them free to change implementation details (which consumers usually don't know or care about) as long as the published specifications are accurate. Then again, drive manufacturers are also known for changing what the definition of a unit of measurement means. Some of us remember when they arbitrarily chan…

I don't really care if a drive is 150MB/s or 200MB/s. I understand that hard drive manufacturers change their technology on a regular basis (PMR, HAMR, etc. etc.). Adding platters, removing platters, increasing platter density, etc. etc. As hard drives change, so do their performance.

What makes this a sore spot, is that SMR drives have something like 1/8th the sustained write performance of PMR drives.

Think about how you went from HDD world into the SSD world a few years back. Except do that in reverse. SMR drives are great for archives, but they should never be sold as a mainstream solution, because their performance is so much worse than PMR.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#85

Post by dragontamer »

otterley wrote: post #67
dragontamer wrote: post #48

Earlier quoted context omitted.

> Are the disk vendors publishing performance metrics that are being violated by the use of SMR technology? Not really, no. SMR drives overlays data on top of each other, like "shingles" on a typical American roof. As such, whenever an SMR drive writes data, it must read the data "underneath" the current spot, rewrite the "underneath" data, and then lay the new data on top of it. SMR drives are great for archives (wr…

I think the real answer here is to demand that disk manufacturers publish performance specifications. This leaves them free to change implementation details (which consumers usually don't know or care about) as long as the published specifications are accurate.

For literally years, people bought WD Red drives, DESPITE being more expensive, because they had higher performance.

WD Blue drives had SMR / Shingles in them. WD Green drives were shoddy, low quality, and had issues with RAID Rebuilds. WD Red commanded a high price, but came with higher quality.

What's happened here, is that WD has begun to sell low-performance drives under their high-priced "Red" brand.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#87

Post by otterley »

dragontamer wrote: post #84
otterley wrote: post #66

Earlier quoted context omitted.

I think the real answer here is to demand that disk manufacturers publish performance specifications. This leaves them free to change implementation details (which consumers usually don't know or care about) as long as the published specifications are accurate. Then again, drive manufacturers are also known for changing what the definition of a unit of measurement means. Some of us remember when they arbitrarily chan…

I don't really care if a drive is 150MB/s or 200MB/s. I understand that hard drive manufacturers change their technology on a regular basis (PMR, HAMR, etc. etc.). Adding platters, removing platters, increasing platter density, etc. etc. As hard drives change, so do their performance. What makes this a sore spot, is that SMR drives have something like 1/8th the sustained write performance of PMR drives. Think about h…

> I don't really care if a drive is 150MB/s or 200MB/s.

You do care about performance - you say so in the next paragraph. In this case, it is rewrite performance. This is quantifiable and can be disclosed on spec sheets and labeling. I'm not saying the recording method can't be disclosed too, but I think to most consumers, the metrics are more important than the technology.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#88

Post by Arbalest »

DeathArrow wrote: post #58
thequux wrote: post #56

The annoying part about all this is that I want to buy some SMR disks (HM ideally, but HA will do) to experiment with storage tech. I know that there are lots of devices out there that are SMR internally, but because of vendors hiding the information, I can't actually buy what I want. (On that note: if anybody has a disk that supports ZAC or ZBC and wants to get rid of it, I'll happily buy it off of them)

Google the exact drive name and SMR. People have started to put together lists.

The parents point was that, by hiding disk type, they are intentionally device managed, not host aware (HA) nor host managed (HM), so do not fit the bill.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#89

Post by Dylan16807 »

m0zg wrote: post #60
dragontamer wrote: post #44

Earlier quoted context omitted.

There are only maybe... 3 or 4 elements of HDD designs worth talking about. * CMR/PMR drives -- Classic hard drive you've been buying for the last 30 years. Not much to say about it. * SMR Drives -- "Shingled" has very poor write performance, but adds 20% more capacity at lower costs. For "write once, read many" workloads, like archival or backups. This is because "Shingled" drives write data on top of the old data,…

I don't know if there's any truth to this, but I've read NAS drives also declare themselves "bad" much more readily through SMART, so you replace them sooner.

It should just be a setting for whether a drive does 0 retries, 1 retry, 5 seconds of retrying, or longer. Not entirely different models.

Re: Toshiba, Seagate shipping slower SMR drives without disclosure, too

#90

Post by ubercow13 »

LeifCarrotson wrote: post #65
ubercow13 wrote: post #27

Earlier quoted context omitted.

They have problems being chucked out of pools when resilvering, ie. when added to the pool, so the general usage pattern isn't so much the issue as is the way the filesystem or RAID controller reacts to them. In particular I think people have had problems with ZFS because the resilvering process involves a lot of random writes, and once the PMR cache on the drive is full, it will stop responding as it flushes the cac…

So we could make the build process pause until the drive resumed responding, or have the ZFS/whatever filesystem drivers recognize the difference between a dead drive and an SMR drive that's working on its cache? I'd want the drive statistics or benchmarks to include a complete rebuild process, though.

Yeah, it does seem like maybe there could be improvements on the filesystem/RAID software side to better support these drives. If only they were labelled properly as SMR so that the filesystem devs could buy one to test with.
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