ZFS requires barely any partitioning in simple cases [LWN.net]

ZFS requires barely any partitioning in simple cases

Posted Jun 25, 2024 11:52 UTC (Tue) by pizza (subscriber, #46)
In reply to: ZFS requires barely any partitioning in simple cases by marcH
Parent article: The GhostBSD in the machine

> Understanding 2. took me a surprisingly long time because it wasn't about learning a new approach: it was about UNlearning the obsolete approach. Unlearning always takes longer. It's also the sure sign of a significantly different and better way!

Except of course that the system firmware [1] only understands partitions, and on top of that also has specific requirements for what can be booted from.

So we're still stuck understanding "classic" partitioning.

[1] UEFI or whatever

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ZFS requires barely any partitioning in simple cases

Posted Jun 25, 2024 13:35 UTC (Tue) by eru (subscriber, #2753) [Link] (1 responses)

Except of course that the system firmware [1] only understands partitions

But in that case you should only need a minimum of two partitions: a small boot partition, and and second for everything else. Still simpler. But Ubuntu created five, when out of curiosity I let its installer use ZFS. Does an EFI system really need two boot partitions?

Device       Start       End   Sectors   Size Type
/dev/sda1     2048      4095      2048     1M BIOS boot
/dev/sda2     4096   1054719   1050624   513M EFI System
/dev/sda3  1054720   5249023   4194304     2G Linux swap
/dev/sda4  5249024   9443327   4194304     2G Solaris boot
/dev/sda5  9443328 976773134 967329807 461,3G Solaris root

ZFS requires barely any partitioning in simple cases

Posted Jun 25, 2024 15:07 UTC (Tue) by jem (subscriber, #24231) [Link]

>Does an EFI system really need two boot partitions?

No. The "BIOS Boot" partition is needed for GRUB, when booting a legacy BIOS (non-EFI) system with a disk that has been partitioned using a GUID Partition Table (GPT).

Originally the space on the disk immediately following the MBR was store the second stage of GRUB. This space was left unallocated by convention. This scheme is incompatible with GPT, so the solution was to create a separate partition, the BIOS Boot partition, for the second stage. This is actually an improvement compared to the old system, since there was no guarantee that the "no man's land" outside of any partition wasn't used for something else, or that it even existed.