101–110 of 130 posts
They should just sell PMR drives, with an option to enable SMR mode for extra capacity.
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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.
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Yeah. QLC is bad but mature TLC with a DRAM cache can be an excellent choice b
QLC with a decent SLC cache seems to work just fine as well, for most consumer purposes - see drives like the sabrent Rocket-Q
I've tried QLC drives for cheap cluster storage. It turns out one QLC drive was slower than 4 old HDDs. I had to go back to HDDs until I switched to TLC flash because they were faster. Tail latencies hitting one second on QLC. It's incredible how bad they are. We shouldn't even be calling them SSDs at that point, they don't even remotely live up to the performance expectations you might have from an SSD.
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> 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.
You'd need a filesystem that was pretty careful to write a very large chunk extremely sequeuntially. That's easiest with Host-aware SMR (to have some idea the size of the zones) or a linear LogFS.
But the point I'm making is that "host-aware" should be good enough for this type of use. Even though it's still drive-managed, the internal logic in the drive should pass through certain write patterns without interference. And you can make the host aware through feeding in a few parameters; it doesn't necessarily have to interrogate the drive.
In other words, I'm disagreeing with the idea that this big laundry list of things would need to be updated. The filesystem should be sufficient if these drives act in a way that's at all reasonable.
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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.
Looking at the WD Purple drive marketing material... they describe "support for 64 cameras". Which means the CCTV community is willing to pay for write bandwidth. It'd probably be a standard 7200 PMR drive, but with assurances and maybe some tests on the write performance.
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> On the SSD side we have DRAMless and TLC. I'm happy to buy a DRAMless + TLC SSD for my boot disk on my web browsing PC (not development), it is a reasonable compromise for a lower price. Same for SMR drives, I won't have problems with them as backup disks. I think the problem here is SMR drives are sold without disclosure , and it has already created some serious problems in practice. > What’s worse, they’re shippi…
> 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.
* Western Digital admits 2TB-6TB WD Red NAS drives use shingled magnetic recording
https://blocksandfiles.com/2020/04/14/wd-red-nas-drives-shin...
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...
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,…
Can't say I particularly care frankly. I don't see myself buying another spinning plate of rust
How do you backup your motionless piles of sand, then? /joke Perhaps all the data you care is on the cloud, but HDDs are still important for backups. Although it's the most acceptable scenario to use an inferior SMR disk. The real issue of SMR is RAID/servers, which, of course, is what the cloud is made of...
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QLC with a decent SLC cache seems to work just fine as well, for most consumer purposes - see drives like the sabrent Rocket-Q
QLC with an SLC cache is the SSD equivalent of SMR. They are fine for read-mostly workloads but performance goes completely down the drain when you do random writes. I've tried QLC drives for cheap cluster storage. It turns out one QLC drive was slower than 4 old HDDs. I had to go back to HDDs until I switched to TLC flash because they were faster. Tail latencies hitting one second on QLC. It's incredible how bad the…
This doesn't come out in tests or consumer experience of the drives that have a significant cache, like the aforementioned "Rocket Q", which has a DRAM cache and a large SLC/TLC cache behind it.
Cluster storage is not a mainstream consumer use.
> We shouldn't even be calling them SSDs at that point
Is the intel 660p range not an SSD? It significantly outperforms SATA SSDs.