Re: [gentoo-user] OT: btrfs raid 5/6

[Neil Bothwick]

On Tue, 12 Dec 2017 00:20:48 +0100, Frank Steinmetzger wrote:

> My new drives are finally here. One of them turned out to be an OEM. -_-
> The shop says it will cover any warranty claims and it’s not a backyard
> seller either, so methinks I’ll keep it.
>
> To evaluate LUKS, I created the following setup (I just love
> ASCII-painting in vim ^^):
>
> ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
> ┃ tmpfs                                                           ┃
> ┃ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ┃
> ┃ │  1 GB file  │ │  1 GB file  │ │  1 GB file  │ │  1 GB file  │ ┃
> ┃ └──────┬──────┘ └──────┬──────┘ └──────┬──────┘ └──────┬──────┘ ┃
> ┃        V               V               V               V        ┃
> ┃ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ┃
> ┃ │ LUKS device │ │ LUKS device │ │ LUKS device │ │ LUKS device │ ┃
> ┃ └──────┬──────┘ └──────┬──────┘ └──────┬──────┘ └──────┬──────┘ ┃
> ┃        V               V               V               V        ┃
> ┃ ┌─────────────────────────────────────────────────────────────┐ ┃
> ┃ │                          RaidZ2                             │ ┃
> ┃ └─────────────────────────────────────────────────────────────┘ ┃
> ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛

That means every write has to be encrypted 4 times, whereas using
encryption in the filesystem means it only has to be done once. I tried
setting encrypted BTRFS this way and there was a significant performance
hit. I'm seriously considering going back to ZoL now that encryption is
on the way.


-- 
Neil Bothwick

A printer consists of three main parts: the case, the jammed paper tray
and the blinking red light.