Hacker News Reader

Comment by allenrb | Hacker News Reader

This is a subject that gets a lot of reviewer attention and results in considerable gnashing of teeth. Yet for most users, how often do we generate many-gigabyte streams of sequential writes? It’s just not a usage pattern worthy of infinite optimization. As others have pointed out already, it’s the reads that matter. In particular, end users care about low queue depth, kind-of-random read throughout. And here, the cheapest SSD thrashes the best spinning disks.

Imho it’s a little bit like complaining that long, sequential writes to DRAM are slower than reads from L1$. It’s true, it just doesn’t matter for most of us.

View on HN

I can attest that getting one of those cheapo SSD-s for a gaming PC and then downloading games on Steam over a good connection (500 Mbit/s) can overwhelm the SSD and cause the whole system to be unusably slow, with similar multi-second latency numbers being shown in Task Manager on Windows 10. It’s a relatively common situation among the gaming community, I’d say.

I've seen people complain exactly about this.

I read that disabling the Windows write cache for the drive helps with this problem. Don't ask me why though.

The OS stops sending bazillions of bytes to the drive, overwhelming its' caches, but waits for the writes to complete. Less throughput from the OS => more time for SSD to complete whatever inner shenanigans are happening.

generally the limit here is windows/antivirus making your storage a ton slower. Linux/Mac don't have this problem nearly as bad.

Windows isn’t alone in this problem… someone uploading gigabytes of files to a web server can cause this too.

Are you talking about a web server running in somebody's basement, or a web server running in a data center? Because the SSDs in a real server wouldn't have SLC caching in the first place.

windows is alone in the problem of having an OS with a really slow file system and being commonly deployed with antivirus that will scan every file.

>> many-gigabyte streams of sequential writes?

More often than many would expect. Downloading/installing games can do it. No doubt many complaints to Valve about slow servers are likely the fault of slow consumer SSDs not able to keep pace with modern download speeds. And people with the smaller/slower SSDs are more likely to be installing/removing games more often. It's a strange strange world where local storage might bottleneck a residential internet connection.

I've run into this when I first got access to gigabit internet. I was still storing all of my games on good old SATA hard drives.

I set up a 4 gigabyte RAM disk for downloads and such so my hard drives weren't slowing me down. Eventually I got myself some nice and fast SSDs, but even now I run some games of hard drives because of the still significant cost of replacing terabytes of storage capacity.

I do long sequential writes quite frequently, copy a media file (often from torrenting) for viewing on another machine or to take to another location. Speed of that does matter.

I disagree strongly.

Writes are often just as important, there is no picking and choosing between read/write performance, both must be acceptable.

And that's true for both sequential and random I/O.

If you ever have to ingest some large data set on any of these cheap SSDs you'll be in for an unwelcome surprise.

And although outside the scope of my article, random write I/O performance is beyond terrible as soon as you're out of the SLC cache.

Reply on news.ycombinator.com