GPT vs MBR for swap devices

[bob prohaska]

On Tue, Jun 19, 2018 at 03:10:44PM +1000, Trev wrote:
> bob prohaska wrote on 19/06/2018 14:00:
> > On Tue, Jun 19, 2018 at 12:34:23PM +1000, Trev wrote:
> >>
> >> Just for reference, with the 32 bit Rpi2, my peak swap usage (with
> >> nothing much other than make -j4 buildworld running) is 1.424GB.
> > 
> > That's a surprise, I thought it would be much less. What is your
> > swap and storage configuration?
> 
> 
> root at rpi2 [/root] $ cat /etc/fstab
> # Custom /etc/fstab for FreeBSD embedded images
> /dev/ufs/rootfs   /       ufs     rw,noatime      1       1
> /dev/msdosfs/MSDOSBOOT /boot/msdos msdosfs rw,noatime 0 0
> md1 /tmp mfs rw,noatime,-s100m 0 0
> md2 /var/log mfs rw,noatime,-s15m 0 0
> md3 /var/tmp mfs rw,noatime,-s15m 0 0
> /dev/label/swap none    swap    sw      0       0
> /dev/ufs/home   /home   ufs     rw,noatime      2       2
> /dev/ufs/usr    /usr    ufs     rw,noatime      2       2
> 
> 
> root at rpi2 [/root] $ gpart show
> =>      63  30318529  mmcsd0  MBR  (14G)
>          63    102375       1  !12  [active]  (50M)
>      102438  30216154       2  freebsd  (14G)
> 
> =>       0  30216154  mmcsd0s2  BSD  (14G)
>           0        90            - free -  (45K)
>          90  30216064         1  freebsd-ufs  (14G)
> 
> =>      40  60567472  da0  GPT  (29G)
>          40         8       - free -  (4.0K)
>          48   4194304    1  freebsd-swap  (2.0G)
>     4194352  54525952    2  freebsd-ufs  (26G)
>    58720304   1847208       - free -  (902M)
> 
> =>      40  60567472  da1  GPT  (29G)
>          40  60567468    1  freebsd-ufs  (29G)
>    60567508         4       - free -  (2.0K)
> 
> 
> root at rpi2 [/root] $ mount
> /dev/ufs/rootfs on / (ufs, local, noatime, soft-updates)
> devfs on /dev (devfs, local)
> /dev/msdosfs/MSDOSBOOT on /boot/msdos (msdosfs, local, noatime)
> /dev/md1 on /tmp (ufs, local, noatime, soft-updates)
> /dev/md2 on /var/log (ufs, local, noatime, soft-updates)
> /dev/md3 on /var/tmp (ufs, local, noatime, soft-updates)
> /dev/ufs/home on /home (ufs, local, noatime, soft-updates)
> /dev/ufs/usr on /usr (ufs, local, noatime, soft-updates)
> 
> 
> da0 at umass-sim0 bus 0 scbus0 target 0 lun 0
> da0: < USB DISK 2.0 PMAP> Removable Direct Access SPC-4 SCSI device
> da0: Serial Number 070B6B2514ABD241
> da0: 40.000MB/s transfers
> da0: 29574MB (60567552 512 byte sectors)
> da0: quirks=0x3<NO_SYNC_CACHE,NO_6_BYTE>
> 
> da1 at umass-sim1 bus 1 scbus1 target 0 lun 0
> da1: < USB DISK 2.0 PMAP> Removable Direct Access SPC-4 SCSI device
> da1: Serial Number 070B6B236F828891
> da1: 40.000MB/s transfers
> da1: 29574MB (60567552 512 byte sectors)
> da1: quirks=0x3<NO_SYNC_CACHE,NO_6_BYTE>
> 
> 
> 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
> _______________________________________________

Are da0 and da1 mechanical disks, or flash?
What's the motive for using /dev/md for /tmp
and /var ?

It does appear that /usr/obj and swap share da0,
the same setup I have, and potentially a source
of congestion. 

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.

Thanks for posting!

bob prohaska