Modern storage is plenty fast, but the APIs are bad • Hacker News Board

Re: Modern storage is plenty fast, but the APIs are bad

#11

Post by zbrozek » Thu, Nov 26, 2020, 5:29 PM UTC

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

What do you do that wears them out so fast? I've been running the same NVMe disk as my daily driver since 2015 and it's not showing any signs of degradation.

Re: Modern storage is plenty fast, but the APIs are bad

#12

Post by blindm » Thu, Nov 26, 2020, 5:30 PM UTC

marcolussetti wrote: post #8

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

Every year seems like a very short lifespan, but I guess every usecase is different. I definitely replace drive when SMART is starting to look bleak, but that is far more infrequent in my usecase I guess.

> Every year seems like a very short lifespan

Yes but I forgot to mention I do a lot of heavy writes to it. It is common to see me creating a huge 20GB virtual machine disk image, using it for a few hours, then deleting it, before creating a new one in its place. I'm a huge virtualization freak.

Re: Modern storage is plenty fast, but the APIs are bad

#13

Post by blindm » Thu, Nov 26, 2020, 5:31 PM UTC

zbrozek wrote: post #11

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

What do you do that wears them out so fast? I've been running the same NVMe disk as my daily driver since 2015 and it's not showing any signs of degradation.

> What do you do that wears them out so fast?

I forgot to mention I do a lot of heavy writes to it. It is common to see me creating a huge 20GB virtual machine disk image, using it for a few hours, then deleting it, before creating a new one in its place. I'm a huge virtualization freak.

Re: Modern storage is plenty fast, but the APIs are bad

#14

Post by _urga » Thu, Nov 26, 2020, 5:32 PM UTC

ivoras wrote: post #2

> ...misconceptions... Yet if you skim through specs of modern NVMe devices you see commodity devices with latencies in the microseconds range and several GB/s of throughput supporting several hundred thousands random IOPS. So where’s the disconnect? Whoa there... let's not compare devices with 20+ GB/s and latencies in nanosecond ranges which translate to half a dozen giga-ops per second (aka RAM) with any kind of f…

The advertised bandwidth for RAM is not actually what you get per-core, which is what you care about in practice.

If you want to know the upper bound on your per-core RAM bandwidth:

64 bytes (the size of a cache line) * 10 slots (in a CPU core's LFB or line fill buffer) / 100ns (the typical cost of a cache miss) * 1000000 * 1000 (to convert ns to ms to seconds) = 6400000000 bytes per second = 5.96 GiB per second RAM bandwidth per core

There's no escaping that upper bound per core.

Nanosecond RAM latencies don't help much when you're capped by the line fill buffer and queuing delay kicks in spiking your cache miss latencies. You can only fetch 10 lines at a time per core and when you exceed your 5.96 GiB per second budget your access times increase.

If you compare with NVMe SSD throughput plus Direct I/O plus io_uring, around 32 GIB per second and divide that by 10 according to the difference in access latencies, then I think the author is about right on target. The point they are making is valid: it's the same order of magnitude.

Re: Modern storage is plenty fast, but the APIs are bad

#15

Post by blindm » Thu, Nov 26, 2020, 5:33 PM UTC

tjoff wrote: post #6

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

The solution for this problem is raid. Way cheaper and far superior in terms of reliability than your solution. Or if that isn't an option (laptop?) a good backup-solution that that runs daily or more often is also a better and cheaper alternative. Drives may dail at any time, but they don't age the way your post would suggest.

I've looked into RAID. It seems a bit complicated to use. Is it trivial to create a RAID array in Linux with zero fuss and the whole thing 'just working' with very little knowledge of the filesystem itself other than it keeps your data 'safe' and redundancy baked in?

Re: Modern storage is plenty fast, but the APIs are bad

#16

Post by thekrendal » Thu, Nov 26, 2020, 5:33 PM UTC

blindm wrote: post #12

marcolussetti wrote: post #8

Earlier quoted context omitted.

Every year seems like a very short lifespan, but I guess every usecase is different. I definitely replace drive when SMART is starting to look bleak, but that is far more infrequent in my usecase I guess.

> Every year seems like a very short lifespan Yes but I forgot to mention I do a lot of heavy writes to it. It is common to see me creating a huge 20GB virtual machine disk image, using it for a few hours, then deleting it, before creating a new one in its place. I'm a huge virtualization freak.

That's still nothing even if you do that 4x/day.

Also just because you create a 20GB virtual disk does not necessarily mean you're actually writing out 20GB to the disk.

Many SSDs and NVMEs are designed with total drive writes per day in their specs.

What is the wear method you're measuring by and what's the threshold where you're replacing your drives?

Re: Modern storage is plenty fast, but the APIs are bad

#17

Post by [deleted] » Thu, Nov 26, 2020, 5:34 PM UTC

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

[deleted]

Re: Modern storage is plenty fast, but the APIs are bad

#18

Post by ahupp » Thu, Nov 26, 2020, 5:36 PM UTC

blindm wrote: post #13

zbrozek wrote: post #11

Earlier quoted context omitted.

What do you do that wears them out so fast? I've been running the same NVMe disk as my daily driver since 2015 and it's not showing any signs of degradation.

> What do you do that wears them out so fast? I forgot to mention I do a lot of heavy writes to it. It is common to see me creating a huge 20GB virtual machine disk image, using it for a few hours, then deleting it, before creating a new one in its place. I'm a huge virtualization freak.

In a lot of these systems (at least VMWare back when I used that, and Docker) you can clone an existing image with copy-on-write. This is a lot faster and would avoid 20GB of writes to spin up a new VM.

Re: Modern storage is plenty fast, but the APIs are bad

#19

Post by porpoise » Thu, Nov 26, 2020, 5:36 PM UTC

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

On the one hand, a new SSD a year sounds extreme.

On the other hand, how many years does each of us have left? Ten? twenty? Thirty? Forty? Few of us can easily imagine ourselves still alive and productive in forty years. So much of what we do rests on an implicit assumption that we are going to live for eternity, and starts to seem pointless when we consider how short our existence is.

Re: Modern storage is plenty fast, but the APIs are bad

#20

Post by gravypod » Thu, Nov 26, 2020, 5:36 PM UTC

blindm wrote: post #4

Also: Modern storage is plenty fast, but also not reliable for long term use. That is why I buy a new SSD every year and clone my current (worn out) SSD to the new one. I have several old SSDs that started to get unhealthy, well, according to my S.M.A.R.T utility that I used to check them. I could probably get away with using an SSD for another year, but will not risk the data loss. Anyone else do this?

It will highly vary depending on use case. I have been using the same SSD (Samsung 850 evo) since 2015. First used on my gaming desktop, then on my college laptop, now in my gaming desktop again. I just make sure to keep it at ~25% to ~50% capacity to give the controller an easy time and I try to stick to mostly read only workloads (gaming). SMART report from that drive: https://pastebin.com/raw/HyPE6aHm

For my disk for my exact use case: ~4 years of operation. 88% of lifespan remaining.

Your mileage will almost definitely vary.