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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

#91

Post by m0zg »

Dylan16807 wrote: post #89
m0zg wrote: post #60

Earlier quoted context omitted.

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.

It probably is a setting. And manufacturers simply make us pay $20-50 more for flipping a bit. I'd be stunned if they have entirely different firmware versions for different products.

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

#92

Post by eggsome »

dragontamer wrote: post #44
canada_dry wrote: post #24

Adding to this confusing debacle is how HDDs are now being marketed like running shoes: one type for running, one for squash, one for tennis, one for basketball...

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,…

"NAS" drives are typically set to not have a timeout mismatch for linux raid.

See here:

https://raid.wiki.kernel.org/index.php/Timeout_Mismatch

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

#93

Post by ngcc_hk »

wtallis wrote: post #76
auxym wrote: post #74

Earlier quoted context omitted.

> For "write once, read many" workloads, like archival or backups. My backup drive gets written to nightly, but reads are very rare (only in case of data loss).

The key aspect of WORM here is that the data you write is not modified in-place or overwritten in part; it stays put until deleted. That's true of most backup strategies, whether or not they generate a lot of read traffic to compute incremental backups. The "read many" part of WORM is usually never about how many actual reads are performed, but about the capability to handle them better than multiple writes.

You are right but the guy you replied highlight a strong point, we want to write once very quickly just to archive something and chance of reading those is low. But we would need to write it. (He did it every night. I just archive it and recycle the storage in my NAS, but not as frequent as every night.). If I want archive reading in the very long term, should use tape or as you say WORM. But not for hard disk usage.

Low cost write quickly. That is the 5400 coming in but not this.

But the key is to tell us so we can choose. Not as scandal like to get such knowledge and still hiding.

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

#94

Post by userbinator »

lonelappde wrote: post #3
fendy3002 wrote: post #2

So does this happened because the rising adaptation of SSD or it's bound to happen after all for HDD to cutting cost?

It's competition. Every cost cutting tech gets adoption except for boost the main muggle specs like capacity. On the SSD side we have DRAMless and TLC. The annoying thing is that unless the government forces disclosure, the honest manufacturers are the ones hurt, having to start advertising "no SMR!" to differentiate, like the organic/health food products in the grocery store that have to list all the poisons they do…

Yes, the NAND flash "decline" (for lack of better words) is sad to see, and it's as you said --- the only marketing spec people seem to care about with storage is capacity.

TLC and QLC are misnomers, a TLC cell holds 3 bits but has eight levels and QLC likewise 4 bits with 16 levels. You get a multiplicative increase in capacity for an exponential decrease in reliability. The manufacturers have been very obfuscatory with the marketing, since they know the inconvenient truth.

Does anyone still make a reasonably large (>100GB) SSD with good old 100K SLC? I have a 64MB (true 2^26 bytes capacity!) flash drive with 100K SLC; 0 bad blocks when it was new, and still 0 bad blocks a decade and a half later despite plenty of abuse.

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

#95

Post by Dylan16807 »

dragontamer wrote: post #82
uluyol wrote: post #59

Earlier quoted context omitted.

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.

How can the best case be slower? The drive spins at the same speed, with normal linear density, and it doesn't need to wait between tracks.

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

#96

Post by ngcc_hk »

loeg wrote: post #61
seized wrote: post #46

Earlier quoted context omitted.

Except filesystems like ZFS are having issues on these SMR Reds during resilvers (rebuilds) because SMR slows down so much.

Toast0's great-grandparent comment (and my grandparent comment) are talking about Host-managed SMR, not "transparent" drive-managed SMR like these fraudulent WD Reds. Yes, nothing except extremely low load or extremely linear (i.e., security video / tape-style backup) workflows works well with drive-managed SMR.

storage drive recycle after certain period and hence it is good for the first write but after that as those (and then as which support it) would need to assume low load environment. May be ok, just if we can tell we can test.

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

#97

Post by Dylan16807 »

londons_explore wrote: post #69
loeg wrote: post #42

Earlier quoted context omitted.

You don't need a single Log structure -- the shingle stripes are on the order of 128 MB of or so. Any CoW filesystem can relatively easily adapt to this kind of system; in-place filesystems are basically boned on SMR. The CoW filesystem aren't going to be fast on SMR, mind you, just not quite as awful.

I believe these SMR drives don't allow direct access to "write a block here". They try to write your writes to a staging area first, and them move them later. The SATA/SCSI spec, together with operating systems, block device interfaces, and filesystems, would all need to be updated to have more parameters to correctly handle SMR drives properly. Since hard drives are going out of fashion and architectural changes lik…

> They try to write your writes to a staging area first, and them move them later.

If a zone is empty, and you try to write sequentially to it, I would sure hope the firmware isn't so hopelessly dumb as to redirect that data to a staging area.

This does require that they don't disable TRIM support, I guess.

I'd really like to see some detailed analysis of how these drives perform.

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

#98

Post by cmurf »

I'm not sure about how to moderate the reported DMSMR behaviors reported in this thread.

But I wonder if folks are better off buying host managed or host aware drives instead, and pairing it with either dm-zoned and their preferred file system; or a file system that supports ZBC and ZAC natively (Btrfs does, I'm not sure about others).

Note that dm-zoned has significant changes starting with kernel 5.5.

https://zonedstorage.io/linux/dm/#

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

#100

Post by lopmotr »

dragontamer wrote: post #44
canada_dry wrote: post #24

Adding to this confusing debacle is how HDDs are now being marketed like running shoes: one type for running, one for squash, one for tennis, one for basketball...

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,…

How do "surveillance" drives fit into that? They're supposed to be special for being reliable with a lot of writing, several orders or magnitude more the drive's capacity. Apparently normal hard drives aren't reliable enough for recording CCTV footage.
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