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Un1corn

Does someone have a comparison between common server ssds and consumer ssds? I wonder if the speed is equal or not

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Hard drives are still about 150MB/s.

SATA SSDs are limited to 550MB/s.

PCI-E 3.0 SSDs more like 3500 MB/s.

PCI-E 4.0 SSDs are 7000MB/s.

All of these are at consumer level pricing, you can get 2TB of PCI-E 4 from Western Digital for £130 at the moment, usually about £180. The issue is sustained writes more than reads for consumer verses enterprise drives where the speed drops off due to a lack of SLC caching and lack of cooling and TLC/QLC which is slower for sustained writing.

The example given is very much a consumer level device and not a particularly quick one by today's standards. You can also expect much faster reads cached than that on a DDR5 system I suspect.

For me main difference between hdd and nvme is not really the throughput but the acces time. When you manipulate small files it's a lot more important

It should be noted that those SSD speeds are all protocol limits rather than NAND flash limits. ~7GB/s is literally the maximum speed PCIE4 can provide, likewise ~3.5GB/s for PCIE3 and ~500MB/s for SATA3.

> the maximum speed PCIE4

4-lane PCIe, as most nvme drives are. I havent seen drives with wider lanes though...

Ah, right. Lanes. I should have mentioned those as well, thanks for catching that.

Todays large hard drives are over 250MBs in sequential operations

Consumer SSDs are trash for sustained writes since they get their top speeds from cache and use slower NAND. Enterprise SSDs tend to have better write endurance, and faster NAND. I have a small Ceph cluster and as an example when I first bought SSDs for it I tried consumer Samsung 870 Evo's. They performed worse than spinning rust.

Consumer SSDs don't really use slower NAND; the QLC vs TLC ratio might be higher for the consumer SSD market than the enterprise SSD market, but a consumer TLC drive is using the same speed of NAND as an enterprise TLC drive (and likewise for QLC drives).

Enterprise SSDs only really have significantly higher endurance if you're looking at the top market segments where a drive is configured with much more spare area than consumer drives (ie. where a 1TiB drive has 800GB usable capacity rather than 960GB or 1000GB). Most of the discrepancy in write endurance ratings between mainstream consumer and mainstream enterprise drives comes from their respective write endurance ratings being calculated according to different criteria, and from consumer SSDs being given low-ball endurance ratings so that they don't cannibalize sales of enterprise drives.

Your poor Ceph performance with Samsung consumer SATA SSDs wasn't due to the NAND, but to the lack of power loss protection on the consumer SSDs leading to poor sync write performance.

If that had been true what you say then we wouldn't be able to saturate the PCIe 3.0 x4 bus with consumer NVMe SSD which we absolutely can. The biggest difference is in the durability as mentioned in the comment below.

Read speeds are similar between consumer and enterprise SSDs; they use the same flash and there's overlap with high-end consumer SSDs using the same controllers as entry-level and mid-range enterprise SSDs.

The main difference is in write performance: consumer SSDs use SLC caching to provide high burst write performance, while server SSDs usually don't and are optimized instead for consistent, sustainable write performance (for write streams of many GB).

Server SSDs also usually have power loss protection capacitors allowing them to safely buffer writes in RAM even when the host requests writes to be flushed to stable storage; consumer drives have to choose between lying to the host and buffering writes dangerously, or having abysmal write performance if the host is not okay with even a little bit of volatile write caching.

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