4 ms·

Debian/Raspbian rngd with -S0 will bite you after a week

eternityforest 5y ago
"Not hammering the crap out of the SD card" needs to be a standard use case that people should think about. There's so much software out there that has problems that come up in exactly the kinds of scenarios one would be likely to want the app for to begin with. Maybe Red Hat or someone should have a checklist of common edge cases that people should try to be sure their app works under, if they have resources to do so.
- lproven 5y ago
  It is funny (as in, not funny at all) how a few common steps I use break stuff these days. Formatting ext2, because journalling doesn't help with failing flash, e.g. USB keys -- it doesn't help you recover anything and it does more writes, hastening wear. No, "just disable journalling on ext4" is not a good answer: it's non-trivial to do, compared with just using a non-journalling filesystem, which is a single step during installation and lasts for the life of that install. Using `noatime` and so on in /etc/fstab also breaks some stuff, such as maildir.
  - eternityforest 5y ago
    What???? There's applications that actually use atime? The only good reason I can think to have it would be a cache or something. Google tells me there's a way to make maildir work, but I'd never even heard of that program till now so IDK. My solution to disk wear is just to only use 1TB+ SSDs, or, if I'm running directly on a Pi SD card(Which you pretty much have to unless you want to totally defeat the purpose of a Pi being cheap and small and low power), to absolutely plaster the filesystem with ramdisks. logs get one, /tmp gets one, Chromium kiosks are the worst offender, that state gets moved to /dev/shm, etc. Don't forget ~/.cache/lxsession/LXDE/run.log though! It can easily completely fill a disk! Lightweight software seems to often be really bad about this, developers care more about simplicity than whether a flash drive will last 5 years or not. I wish ext4 and ext2 could be replaced. Too bad we don't have anything better, filesystems are all crap. BTRFS has write amplification on small writes, F2FS looks most promising but still has trouble with power loss corruption, ext4 and ext2 don't have compression or CoW, exFAT doesn't have journaling ot anything to protect itself from errors as far as I can tell..
    - lproven 5y ago
      Maildir isn't an application. It's a storage format for email inboxes; multiple email clients support it. Offhand, it's the only thing I know, but yes, it's real and yes it's an issue. I use zram (and tmpfs) on RasPis to provide swap without hammering the µSD card, but the issue with Pis is of course that RAM is scant. The 8GB Pi is impossible to buy at the moment and has been for months; even the 4GB one is in short supply. I am surprised that there doesn't seem to be more effort on Flash-specific general-purpose filesystems, but I'm actively glad ext2 is still a thing. It's perfectly possible to install Linux onto a USB key (not write an ISO and make a bootable key; a full install on USB) and such things can be handy. Ext2 is faster _and_ reduces wear on the medium. Like installing Windows onto an external drive on an Intel Mac, the trick is to attach the drive to a VM, and then install the OS inside the VM. Then, once 1st stage install is done (Windows) or once it's installed (Linux, because there is only 1 stage), just boot the machine off the USB drive directly, without virtualisation.

"Not hammering the crap out of the SD card" needs to be a standard use case that people should think about. There's so much software out there that has problems that come up in exactly the kinds of scenarios one would be likely to want the app for to begin with. Maybe Red Hat or someone should have a checklist of common edge cases that people should try to be sure their app works under, if they have resources to do so.

lproven 5y ago
It is funny (as in, not funny at all) how a few common steps I use break stuff these days. Formatting ext2, because journalling doesn't help with failing flash, e.g. USB keys -- it doesn't help you recover anything and it does more writes, hastening wear. No, "just disable journalling on ext4" is not a good answer: it's non-trivial to do, compared with just using a non-journalling filesystem, which is a single step during installation and lasts for the life of that install. Using `noatime` and so on in /etc/fstab also breaks some stuff, such as maildir.
- eternityforest 5y ago
  What???? There's applications that actually use atime? The only good reason I can think to have it would be a cache or something. Google tells me there's a way to make maildir work, but I'd never even heard of that program till now so IDK. My solution to disk wear is just to only use 1TB+ SSDs, or, if I'm running directly on a Pi SD card(Which you pretty much have to unless you want to totally defeat the purpose of a Pi being cheap and small and low power), to absolutely plaster the filesystem with ramdisks. logs get one, /tmp gets one, Chromium kiosks are the worst offender, that state gets moved to /dev/shm, etc. Don't forget ~/.cache/lxsession/LXDE/run.log though! It can easily completely fill a disk! Lightweight software seems to often be really bad about this, developers care more about simplicity than whether a flash drive will last 5 years or not. I wish ext4 and ext2 could be replaced. Too bad we don't have anything better, filesystems are all crap. BTRFS has write amplification on small writes, F2FS looks most promising but still has trouble with power loss corruption, ext4 and ext2 don't have compression or CoW, exFAT doesn't have journaling ot anything to protect itself from errors as far as I can tell..
  - lproven 5y ago
    Maildir isn't an application. It's a storage format for email inboxes; multiple email clients support it. Offhand, it's the only thing I know, but yes, it's real and yes it's an issue. I use zram (and tmpfs) on RasPis to provide swap without hammering the µSD card, but the issue with Pis is of course that RAM is scant. The 8GB Pi is impossible to buy at the moment and has been for months; even the 4GB one is in short supply. I am surprised that there doesn't seem to be more effort on Flash-specific general-purpose filesystems, but I'm actively glad ext2 is still a thing. It's perfectly possible to install Linux onto a USB key (not write an ISO and make a bootable key; a full install on USB) and such things can be handy. Ext2 is faster _and_ reduces wear on the medium. Like installing Windows onto an external drive on an Intel Mac, the trick is to attach the drive to a VM, and then install the OS inside the VM. Then, once 1st stage install is done (Windows) or once it's installed (Linux, because there is only 1 stage), just boot the machine off the USB drive directly, without virtualisation.