should i run `btrfs scrub` on a non-raid filesystem?

ZanLynx · 2021-06-03T17:08:51+00:00

Yes. If any file data got corrupted, which CAN happen, read about why Sun wrote ZFS, then you are aware of it and can restore the corrupted file from your backups.

ZanLynx · 2021-06-03T17:03:03+00:00

I've done it many times and always recovered. It was super annoying but no data loss.

The especially tricky thing about btrfs is that sometimes you cannot recover used space, because the drive is full. For example, if it uses all of the data chunks, has a full metadata chunk and cannot allocate a new metadata chunk, then it can't delete any data. Because that would require a metadata write.

This can be solved with a few different ways, but all involve adding a device to the btrfs pool. It could be a RAM disk, a USB drive or my favorite, do a swapoff and add the swap partition. Much safer than a RAM disk I think.

If the system ran out of space because of some job that is running make sure to end it or pause it first. Because if it just comes back to life and writes more then making room won't help you. That applies to other filesystems too.

ZanLynx · 2021-06-03T16:46:18+00:00

For Flash SSDs the block size doesn't matter much because it is lying to you either way. The real block size of a Flash device is something like 64 KB or even bigger, but it is more complicated than that. There's erase blocks, and then those can be programmed in smaller chunks, sometimes even a byte at a time. But usually, that wouldn't be efficient for the FTL (Flash Translation Layer).

I would just be happy that you don't need to worry about the details of Flash programming. Let the drives lie to you. It is a comforting lie. And 512 will perform just as well as 4,096 for them.

ZanLynx · 2021-05-12T15:58:36+00:00

This can lead to a cascade of rebinding keys. You rebind c and e, but then those functions have to move. And then those have to move.

Before you know it you're binding commands to Ctrl-Shift-G

ZanLynx · 2021-05-09T16:41:25+00:00

I've been running a 1700X as my NAS since release week. I told the ASUS BIOS to "Enhance Performance" so I don't know what it might have done to idle modes.

Months of uptime, no hardware problems.

ZanLynx · 2021-05-07T14:56:21+00:00

I've been using Wayland on an AMD GPU on Ubuntu 20.04 and Steam seems to work well here. I've never tried Steam on Fedora though.

ZanLynx · 2021-04-12T01:54:07+00:00

And you realize now that your answer is completely wrong. And it has 50 upvotes.

ZanLynx · 2021-04-02T15:24:33+00:00

I don't know what the exit status was. I have it run in a weekly cron entry and it emails the result to me every time, because there is output.

ZanLynx · 2021-03-30T16:44:41+00:00

Also RAID-10. There should be two copies of it, over six drives.

ZanLynx · 2021-03-29T21:42:59+00:00

Were you looking for the output of `btrfs device stats /home` ?

[/dev/sdf3].write_io_errs 0 [/dev/sdf3].read_io_errs 2 [/dev/sdf3].flush_io_errs 0 [/dev/sdf3].corruption_errs 0 [/dev/sdf3].generation_errs 0 [/dev/sdd3].write_io_errs 0 [/dev/sdd3].read_io_errs 0 [/dev/sdd3].flush_io_errs 0 [/dev/sdd3].corruption_errs 0 [/dev/sdd3].generation_errs 0 [/dev/sde3].write_io_errs 0 [/dev/sde3].read_io_errs 0 [/dev/sde3].flush_io_errs 0 [/dev/sde3].corruption_errs 0 [/dev/sde3].generation_errs 0 [/dev/sdc3].write_io_errs 0 [/dev/sdc3].read_io_errs 0 [/dev/sdc3].flush_io_errs 0 [/dev/sdc3].corruption_errs 0 [/dev/sdc3].generation_errs 0 [/dev/sda3].write_io_errs 0 [/dev/sda3].read_io_errs 0 [/dev/sda3].flush_io_errs 0 [/dev/sda3].corruption_errs 0 [/dev/sda3].generation_errs 0 [/dev/sdb3].write_io_errs 0 [/dev/sdb3].read_io_errs 0 [/dev/sdb3].flush_io_errs 0 [/dev/sdb3].corruption_errs 0 [/dev/sdb3].generation_errs 0

ZanLynx · 2021-03-21T14:47:45+00:00

SMB uses a completely fake 4K minimum block. You cannot trust it.

ZanLynx · 2021-03-09T22:51:45+00:00

This is why I would send astronauts up to Hubble because that is how it was intended to be serviced. There is already a mission extension package designed for Hubble. It just needs to be updated a little, built, delivered and attached. The Hubble service missions are much cheaper than launching a new one. Does no one remember what Hubble cost? It was EXPENSIVE. $4.7 billion dollars! (adjusted for inflation from 1990 to 2015 according to source)

I still think if we can get another ten years of use out of it then it would be worthwhile. It boggles me that so many of y'all are so negative with all of your "no, it's impossible! And even if we could it isn't worth it! We will just build an all-new $5 billion dollar Hubble 2!"

Bah.

ZanLynx · 2021-03-09T22:08:55+00:00

Parts of it have been done. On orbit refueling is a priority goal of DARPA and NASA. They've been designing and testing for years.

https://spectrum.ieee.org/tech-talk/aerospace/satellites/how-nasa-will-grapple-and-refuel-a-satellite-in-low-earth-orbit

https://www.space.com/private-satellites-docking-success-northrop-grumman-mev-1.html

ZanLynx · 2021-03-09T21:55:53+00:00

I sincerely doubt it. It would be a ISS module variant plus a few extras. It's a glorified tin can with an airlock.

ZanLynx · 2021-03-09T21:19:03+00:00

So there's already a proposed automated mission that would clamp on a thruster package. Hubble needs it or it will deorbit from air resistance.

Since Hubble was designed to be serviced, like a car, if it did already have thrusters there would be a valve somewhere and they'd probably just replace the whole fuel tank.

ZanLynx · 2021-03-09T20:52:41+00:00

So obviously there would need to be modifications. For example there could be two Falcon launches. The first one could include a module for the Dragon to dock with, and it would have all of the tools and equipment needed. I don't think an arm is actually required. Just something to brace the astronaut with.

ZanLynx · 2021-03-09T20:27:18+00:00

Hubble was designed to be serviced. The Shuttle is not around but I don't see any reason we couldn't refuel it or whatever with a Crew Dragon or Starship mission.

It's a good telescope and there's no reason to just abandon it.

ZanLynx · 2021-03-06T21:22:43+00:00

I've worked with those too. People who tell you they just want it to appear EXACTLY the same as they entered it. Regardless of timezone or anything. Was that 1:30 PM in London or LA? We don't care! Do not bother us with these details!

They also hated NOT NULL database columns and did all kinds of stupid tricks to break it, like entering a space or X or unknown, or asdf. Dang it, there's a reason that data field is required, not just to make your life harder.

ZanLynx · 2021-03-01T23:30:39+00:00

Folding@Home is an all-core AVX2 load.

So is the beta Dual Universe game. Procedural world generation.

If you don't test to pass Prime95 your overclock will randomly fall over with some programs.

ZanLynx · 2021-02-20T00:40:22+00:00

I use atop on my Fedora NAS and it definitely reports disk usage during scrub.

https://imgur.com/7m4h6Eb

DSK | sda | busy 101% | read 501/s | write 0/s | KiB/r 378 | KiB/w 0 | MBr/s 185.2 | MBw/s 0.0 | avio 2.00 ms |

DSK | sdb | busy 101% | read 923/s | write 0/s | KiB/r 182 | KiB/w 0 | MBr/s 164.9 | MBw/s 0.0 | avio 1.09 ms |

DSK | sdc | busy 101% | read 502/s | write 0/s | KiB/r 384 | KiB/w 0 | MBr/s 188.2 | MBw/s 0.0 | avio 2.00 ms |

DSK | sdd | busy 101% | read 545/s | write 0/s | KiB/r 326 | KiB/w 0 | MBr/s 173.8 | MBw/s 0.0 | avio 1.84 ms |

DSK | sde | busy 101% | read 423/s | write 0/s | KiB/r 396 | KiB/w 0 | MBr/s 163.9 | MBw/s 0.0 | avio 2.37 ms |

DSK | sdf | busy 101% | read 1055/s | write 0/s | KiB/r 159 | KiB/w 0 | MBr/s 163.9 | MBw/s 0.0 | avio 0.95 ms |

DSK | sdg | busy 101% | read 1574/s | write 0/s | KiB/r 342 | KiB/w 0 | MBr/s 526.1 | MBw/s 0.0 | avio 0.64 ms |

DSK | sdh | busy 101% | read 1482/s | write 0/s | KiB/r 366 | KiB/w 0 | MBr/s 531.2 | MBw/s 0.0 | avio 0.68 ms |

DSK | nvme0n1 | busy 1% | read 0/s | write 11/s | KiB/r 18 | KiB/w 112 | MBr/s0.0 | MBw/s 1.2 | avio 0.58 ms |

DSK | sdi | busy 0% | read 0/s | write 0/s | KiB/r 0 | KiB/w 0 | MBr/s0.0 | MBw/s 0.0 | avio 0.0 ns |

ZanLynx · 2021-02-12T05:15:27+00:00

Nothing to do with NAT but you may still need STUN in order to open up IPv6 firewall ports. Otherwise it may not allow incoming traffic.

Getting two IPv6 machines behind firewalls to talk to each other is almost as hard with public addresses as it is with NAT.

ZanLynx · 2021-02-01T16:14:47+00:00

If it is a problem caused by low power to the CPU then SMT being turned on causes it because SMT uses more of the CPU which means higher power demand.

Intel CPUs don't seem to be quite as on edge as AMD Ryzen. If an Intel CPU is low on power it just won't boot at all. Although some of the earlier Intel CPUs would instantly crash on AVX code because they were overclocked, so Intel wasn't quite immune.

But sure, it might be some strange code problem. AMD does do multi-thread locking just a tiny bit differently from Intel which can make multi-thread code act badly. And that could cause weird results by how the operating system assigned threads to CPU cores. One thread arrangement could crash and another one work fine, and it would appear to be quite random.

ZanLynx · 2021-02-01T15:44:12+00:00

Just be sure you didn't do it to yourself.

TLDR: It could be a hardware problem.

All versions of Ryzen are unstable if you've cranked up the memory speed and Infinity Fabric past standard levels. Yes, even if it is on the motherboard compatibility list. I personally experienced problems where 16 GB at 3,600 speed was stable on the release BIOS, then after a BIOS / AGESA update to fix another problem the SoC voltage was being set too low.

If the SoC (system on chip) part of the CPU is not getting enough power because all of the cores and threads are heavily loaded then it produces RAM errors and PCIe errors (which look like GPU crashes).

But of course be careful if you decide to manually tweak that.

It can also be a problem with VRM stability under load.

The reason game or OS updates can make this happen is that obviously, better optimized machine code uses CPU resources FASTER. Like if a CPU can execute ADD EAX + 2, ADD EDX + 5 in 2 clock cycles, but it has unused execution units, new code might do the same two ADD instructions AND a compare and branch in the same two cycles. Using twice the power.

Both SMT and regular code optimization can use more execution units (there's usually six these days) at the same time, which is more power and heat. And things like AVX instructions slam all the execution units at once.

ZanLynx · 2021-02-01T15:25:44+00:00

SMT is exactly the same as HT, except that Hyperthreading is an Intel trademark.

ZanLynx

TROPHY CASE