GPT vs MBR for swap devices

bob prohaska fbsd at
Tue Jun 19 23:55:11 UTC 2018

On Wed, Jun 20, 2018 at 07:23:02AM +1000, Trev wrote:
> bob prohaska wrote on 20/06/2018 01:43:
> > On Tue, Jun 19, 2018 at 03:10:44PM +1000, Trev wrote:
> >> bob prohaska wrote on 19/06/2018 14:00:
> [...]
> >> da0 - 32G Emtec USB memory - houses /home and 2G swap partition
> >> da1 - 32G Emtec USB memory - houses /usr
> >>
> >> /usr/obj is linked to /home/obj
So traffic for both /usr/obj and swap has to go through da0?
I'm surprised you aren't seeing difficulties similar to mine.

> > Are da0 and da1 mechanical disks, or flash?
> As above, Emtec USB2 memory keys.
Sorry, didn't recognize the brand name. A brief web search
suggests they aren't particularly fast at 4k random write.
Do you know of any performance data? From what I've seen
on the web it's rather surprising your setup does not have
problems as mine does.

> > What's the motive for using /dev/md for /tmp
> > and /var ?
> /tmp, /var/tmp and /var/log are using /dev/md to save the sdcard from 
> excessive writes. /tmp at least is also used during buildworld and 
> needed bumping up from whatever the default size was to its current 
> 100MB so as not to be exhausted during builds.
> > How old is your Pi2? Mine is the early version,
> > armv7. Later models are armv8. They're identified
> > as V1.1 and V1.2, I think.
> It's an original rpi2 with an ARM Cortex-A7.

Apologies for not thinking to ask earlier, but what
version of FreeBSD are you using? Right now my test
Pi2 is on 11-stable, swap usage appears to peak
at around 140 MB. However, /var and /tmp are on
flash partitions, not md.

Thanks for writing!

bob prohaska

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