423: Hopeful for HAMR

We explore the potential of heat-assisted magnetic recording and get excited about a possibly persistent L2ARC.

Plus Jim's journeys with Clear Linux, and why Ubuntu 18.04.4 is a maintenance release worth talking about.

Links:

• Ubuntu 18.04.4 LTS: here's what's new — It's not as shiny and exciting as entirely new versions, of course, but it does pack in some worthwhile security and bugfix upgrades, as well as support for more and newer hardware.
• 18.04.4 - Ubuntu Wiki
• MobaXterm — Enhanced terminal for Windows with X11 server, tabbed SSH client, network tools and much more.
• Linux distro review: Intel’s own Clear Linux OS — There's not much question that Clear Linux is your best bet if you want to turn in the best possible benchmark numbers. The question not addressed here is, what's it like to run Clear Linux as a daily driver? We were curious, so we took it for a spin.
• Clear Linux* Project — Clear Linux OS is an open source, rolling release Linux distribution optimized for performance and security, from the Cloud to the Edge, designed for customization, and manageability.
• swupd — Documentation for Clear Linux* project
• clr-boot-manager: Kernel & Boot Loader Management
• Cannot compile zfs for 5.5-rc2 · Issue #9745 · zfsonlinux/zfs
• Persistent L2ARC might be coming to ZFS on Linux — The primary ARC is kept in system RAM, but an L2ARC device can be created from one or more fast disks. In a ZFS pool with one or more L2ARC devices, when blocks are evicted from the primary ARC in RAM, they are moved down to L2ARC rather than being thrown away entirely. In the past, this feature has been of limited value, both because indexing a large L2ARC occupies system RAM which could have been better used for primary ARC and because L2ARC was not persistent across reboots.
• Persistent L2ARC by gamanakis · Pull Request #9582 · zfsonlinux/zfs — This feature implements a light-weight persistent L2ARC metadata structure that allows L2ARC contents to be recovered after a reboot. This significantly eases the impact a reboot has on read performance on systems with large caches.
• LINUX Unplugged 303: Stateless and Dateless — We visit Intel to figure out what Clear Linux is all about and explain a few tricks that make it unique.
• LINUX Unplugged Blog: Clear Linux OS 2019
• HAMR don’t hurt ’em: laser-assisted hard drives are coming in 2020 — Although the 2012 "just around the corner" HAMR drives seem to have been mostly vapor, the technology is a reality now. Seagate has been trialing 16TB HAMR drives with select customers for more than a year and claims that the trials have proved that its HAMR drives are "plug and play replacements" for traditional CMR drives, requiring no special care and having no particular poor use cases compared to the drives we're all used to.
• HAMR Milestone: Seagate Achieves 16TB Capacity on Internal HAMR Test Units
• Western Digital debuts 18TB and 20TB near-MAMR disk drives
• Previously on TechSNAP 341: HAMR Time — We've got bad news for Wifi-lovers as the KRACK hack takes the world by storm; We have the details & some places to watch to make sure you stay patched. Plus, some distressing revelations about third party access to your personal information through some US mobile carriers. Then we cover the ongoing debate over HAMR, MAMR, and the future of hard drive technology & take a mini deep dive into the world of elliptic curve cryptography.