Headlines

Checksumming in filesystems, and why ZFS is doing it right

One of the best aspects of ZFS is its reliability. This can be accomplished using a few features like copy-on-write approach and checksumming. Today we will look at how ZFS does checksumming and why it does it the proper way. Most of the file systems don’t provide any integrity checking and fail in several scenarios:

• Data bit flips - when the data that we wanted to store are bit flipped by the hard drives, or cables, and the wrong data is stored on the hard drive.
• Misdirected writes - when the CPU/cable/hard drive will bit flip a block to which the data should be written.
• Misdirected read - when we miss reading the block when a bit flip occurred.
• Phantom writes - when the write operation never made it to the disk. For example, a disk or kernel may have some bug that it will return success even if the hard drive never made the write. This problem can also occur when data is kept only in the hard drive cache.

Checksumming may help us detect errors in a few of those situations.

DragonFlyBSD Improves Its TMPFS Implementation For Better Throughput Performance

It's been a while since last having any new magical optimizations to talk about by DragonFlyBSD lead developer Matthew Dillon, but on Wednesday he landed some significant temporary file-system "TMPFS" optimizations for better throughput including with swap.

Of several interesting commits merged tonight, the improved write clustering is a big one. In particular, "Reduces low-memory tmpfs paging I/O overheads by 4x and generally increases paging throughput to SSD-based swap by 2x-4x. Tmpfs is now able to issue a lot more 64KB I/Os when under memory pressure."

• https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/4eb0bb82efc8ef32c4357cf812891c08d38d8860

There's also a new tunable in the VM space as well as part of his commits on Wednesday night. This follows a lot of recent work on dsynth, improved page-out daemon pipelining, and other routine work.

• https://gitweb.dragonflybsd.org/dragonfly.git/commit/bc47dbc18bf832e4badb41f2fd79159479a7d351

This work is building up towards the eventual DragonFlyBSD 5.8 while those wanting to try the latest improvements right away can find their daily snapshots.

News Roundup

Why ZFS is not good at growing and reshaping pools (or shrinking them)

recently read Mark McBride's Five Years of Btrfs (via), which has a significant discussion of why McBride chose Btrfs over ZFS that boils down to ZFS not being very good at evolving your pool structure. You might doubt this judgment from a Btrfs user, so let me say as both a fan of ZFS and a long term user of it that this is unfortunately quite true; ZFS is not a good choice if you want to modify your pool disk layout significantly over time. ZFS works best if the only change in your pools that you do is replacing drives with bigger drives. In our ZFS environment we go to quite some lengths to be able to expand pools incrementally over time, and while this works it both leaves us with unbalanced pools and means that we're basically forced to use mirroring instead of RAIDZ.

(An unbalanced pool is one where some vdevs and disks have much more data than others. This is less of an issue for us now that we're using SSDs instead of HDs.)

Using PKGSRC on Manjaro Linux aarch64 Pinebook-pro

I wanted to see how pkgsrc works on aarch64 Linux Manjaro since it is a very mature framework that is very portable and supported by many architectures – pkgsrc (package source) is a package management system for Unix-like operating systems. It was forked from the FreeBSD ports collection in 1997 as the primary package management system for NetBSD.

One might question why use pkgsrc on Arch based Manjaro, since the pacman package repository is very good on its own. I see alternative pkgsrc as a good automated build framework that offers a way to produce independent build environment /usr/pkg that does not interfere with the current Linux distribution in any way (all libraries are statically built)

I have used the latest Manjaro for Pinebookpro and standard recommended tools as mentioned here https://wiki.netbsd.org/pkgsrc/how_to_use_pkgsrc_on_linux/

A Central Log Host with syslog-ng on FreeBSD

• Part 1

syslog-ng is the Swiss army knife of log management. You can collect logs from any source, process them in real time and deliver them to wide range of destinations. It allows you to flexibly collect, parse, classify, rewrite and correlate logs from across your infrastructure. This is why syslog-ng is the perfect solution for the central log host of my (mainly) FreeBSD based infrastructure.

• Part 2

This blog post continues where the blog post A central log host with syslog-ng on FreeBSD left off. Open source solutions to check syslog log messages exist, such as Logcheck or Logwatch. Although these are not too difficult to implement and maintain, I still found these to much. So I went for my own home grown solution to check the syslog messages of the SoCruel.NU central log host.

Beastie Bits

• FreeBSD at Linux Conf 2020 session videos now online
• Unlock your laptop with your phone
• Managing a database of vulnerabilities for a package system: the pkgsrc study
• Hamilton BSD User group will meet again on March 10th](http://studybsd.com/)
• CharmBUG Meeting: March 24th 7pm in Severn, MD ***

Feedback/Questions

• Andrew - ZFS feature Flags
• Sam - TwinCat BSD
• Dacian - Freebsd + amdgpu + Lenovo E595

• Send questions, comments, show ideas/topics, or stories you want mentioned on the show to feedback@bsdnow.tv

This episode was brought to you by

Headlines

Enabling FreeBSD on AArch64

• One of the things the FreeBSD foundation has been dumping money into lately is ARM64 support, but we haven't heard too much about it - this article should change that
• Since it's on a mainstream ARM site, the article begins with a bit of FreeBSD history, leading up to the current work on ARM64
• There's also a summary of some of the ARM work done at this year's BSDCan, including details about running it on the Cavium ThunderX platform (which has 48 cores)
• As of just a couple months ago, dtrace is even working on this new architecture
• Come 11.0-RELEASE, the plan is for ARM64 to get the same "tier 1" treatment as X86, which would imply binary updates for base and ports - something Raspberry Pi users often complain about not having ***

OpenBSD's tcpdump detailed

• Most people are probably familiar with tcpdump, a very useful packet sniffing and capturing utility that's included in all the main BSD base systems
• This video guide is specifically about the version in OpenBSD, which has gone through some major changes (it's pretty much a fork with no version number anymore)
• Unlike on the other platforms, OpenBSD's tcpdump will always run in a chroot as an unprivileged user - this has saved it from a number of high-profile exploits
• It also has support for the "pf.os" system, allowing you to filter out operating system fingerprints in the packet captures
• There's also PF (and pflog) integration, letting you see which line in your ruleset triggered a specific match
• Being able to run tcpdump directly on your router is pretty awesome for troubleshooting ***

More FreeBSD foundation at BSDCan

• The FreeBSD foundation has another round of trip reports from this year's BSDCan
• First up is Kamil Czekirda, who gives a good summary of some of the devsummit, FreeBSD-related presentations, some tutorials, getting freebsd-update bugs fixed and of course eating cake
• A second post from Christian Brueffer, who cleverly planned ahead to avoid jetlag, details how he got some things done during the FreeBSD devsummit
• Their third report is from our buddy Warren Block, who (unsurprisingly) worked on a lot of documentation-related things, including getting more people involved with writing them
• In true doc team style, his report is the most well-written of the bunch, including lots of links and a clear separation of topics (doc lounge, contributing to the wiki, presentations...)
• Finally, the fourth one comes to us from Shonali Balakrishna, who also gives an outline of some of the talks
• "Not only does a BSD conference have way too many very smart people in one room, but also some of the nicest." ***

DragonFly on the Chromebook C720

• If you've got one of the Chromebook laptops and weren't happy with the included OS, DragonFlyBSD might be worth a go
• This article is a "mini-report" on how DragonFly functions on the device as a desktop, and
• While the 2GB of RAM proved to be a bit limiting, most of the hardware is well-supported
• DragonFly's wiki has a full guide on getting set up on one of these devices as well ***

Interview - David Meyer - info@xinuos.com / @xinuos

Xinuos, BSD license model vs. others, community interaction

News Roundup

Introducing LiteBSD

• We definitely don't talk about 4.4BSD a lot on the show
• LiteBSD is "a variant of [the] 4.4BSD operating system adapted for microcontrollers"
• If you've got really, really old hardware (or are working in the embedded space) then this might be an interesting hobby project to look info ***

HardenedBSD announces ASLR completion

• HardenedBSD, now officially a full-on fork of FreeBSD, has declared their ASLR patchset to be complete
• The latest and last addition to the work was VDSO (Virtual Dynamic Shared Object) randomization, which is now configurable with a sysctl
• This post gives a summary of the six main features they've added since the beginning
• Only a few small things are left to do - man page cleanups, possibly shared object load order improvements ***

Unlock the reaper

• In the ongoing quest to make more of OpenBSD SMP-friendly, a new patch was posted that unlocks the reaper in the kernel
• When there's a zombie process causing a resource leak, it's the reaper's job to deallocate their resources (and yes we're still talking about computers, not horror movies)
• Initial testing has yielded positive results and no regressions
• They're looking for testers, so you can install a -current snapshot and get it automatically
• An updated version of the patch is coming soon too
• A hackathon is going on right now, so you can expect more SMP improvements in the near future ***

The importance of mentoring

• Adrian Chadd has a blog post up about mentoring new users, and it tells the story of how he originally got into FreeBSD
• He tells the story of, at age 11, meeting someone else who knew about making crystal sets that became his role model
• Eventually we get to his first FreeBSD 1.1 installation (which he temporarily abandoned for Linux, since it didn't have a color "ls" command) and how he started using the OS
• Nowadays, there's a formal mentoring system in FreeBSD
• While he talks about FreeBSD in the post, a lot of the concepts apply to all the BSDs (or even just life in general) ***

Feedback/Questions

• Sean writes in
• Herminio writes in
• Stuart writes in
• Richard writes in ***